text:
Porphyria cutanea tarda

Porphyria cutanea tarda is the most common subtype of porphyria. The disease is named because it is a porphyria that often presents with skin manifestations later in life. The disorder results from low levels of the enzyme responsible for the fifth step in heme production. Heme is a vital molecule for all of the body's organs. It is a component of hemoglobin, the molecule that carries oxygen in the blood.

Hepatoerythropoietic porphyria has been described as a homozygous form of porphyria cutanea tarda, although it can also be caused if two different mutations occur at the same locus.

Symptoms and signs
Porphyria cutanea tarda (PCT) is recognized as the most prevalent subtype of porphyritic diseases.

PCT is characterized by onycholysis and blistering of the skin in areas that receive higher levels of exposure to sunlight. The primary cause is a deficiency of uroporphyrinogen decarboxylase (UROD), a cytosolic enzyme that is a step in the enzymatic pathway that leads to the synthesis of heme. Behind the direct cause there are a number of genetic and environmental risk factors.

Patients who are diagnosed with PCT typically seek treatment following the development of photosensitivities causing blisters and erosions on exposed areas of the skin. This is usually observed in the face, hands, forearms, and lower legs. Healing is slow and leaves scarring. Though blisters are the most common skin manifestations of PCT, other skin manifestations include hyperpigmentation (similar to a tan) and hypertrichosis (mainly on the cheeks) also occur. PCT is a chronic condition, with external symptoms often subsiding and recurring as a result of multiple factors. In addition to the skin lesions, chronic liver disease is very common in patients with sporadic PCT. This involves hepatic fibrosis (scarring of the liver), and inflammation. However, liver problems are less common in patients with the inherited form of the disease. Additionally, patients will often void a wine-red color urine with an increased concentration of uroporphyrin I due to their enzymatic deficiency.

Vitamin, mineral, and enzyme deficiencies
Certain vitamin and minerals deficiencies are common in people with porphyria cutanea tarda. The most common deficiencies are beta-Carotene, retinol, vitamin A and vitamin C. Beta-Carotene is required to synthesize vitamin A and vitamin A is needed to synthesize retinol. A lack of retinol-binding protein is due to a lack of retinol which is required to trigger its production.

Porphyrins interact with iron, absorbing photons to create reactive oxygen species is the mechanism of action causing the itchy, painful blisters of PCT. The reactive oxygen species consume the skin antioxidants beta-carotene, vitamin E, and vitamin C. Supplementation of these three vitamins reduces the oxidation and potentially diminishes the severity of blister formation. No single one of the three vitamins can inhibit the damaging effects of oxidized porphyrins, specifically uroporphyrins and coproporphyrins, but all three working together synergistically are capable of neutralizing their damaging effects.

Genetics
Inherited mutations in the UROD gene cause about 20% of cases (the other 80% of cases do not have mutations in UROD, and are classified as sporadic). UROD makes an enzyme called uroporphyrinogen III decarboxylase, which is critical to the chemical process that leads to heme production. The activity of this enzyme is usually reduced by 50% in all tissues in people with the inherited form of the condition.

Nongenetic factors such as excess iron or partially genetic factors such as alcohol use disorder and others listed above can increase the demand for heme and the enzymes required to make heme. The combination of this increased demand and reduced activity of uroporphyrinogen decarboxylase disrupts heme production and allows byproducts of the process to accumulate in the body, triggering the signs and symptoms of porphyria cutanea tarda.

The HFE gene makes a protein that helps cells regulate the absorption of iron from the digestive tract and into the cells of the body. Certain mutations in the HFE gene cause hemochromatosis (an iron overload disorder). People who have these mutations are also at an increased risk of developing porphyria cutanea tarda.

In the 20% of cases where porphyria cutanea tarda is inherited, it is inherited in an autosomal dominant pattern, which means one copy of the altered gene is sufficient to decrease enzyme activity and cause the signs and symptoms of the disorder.

Other
While inherited deficiencies in uroporphyrinogen decarboxylase often lead to the development of PCT, there are a number of risk factors that can both cause and exacerbate the symptoms of this disease. One of the most common risk factors observed is infection with the Hepatitis C virus. One review of a collection of PCT studies noted Hepatitis C infection in 50% of documented cases of PCT. Additional risk factors include alcohol use disorder, excess iron (from iron supplements as well as cooking on cast iron skillets), and exposure to chlorinated cyclic hydrocarbons and Agent Orange.

It can be a paraneoplastic phenomenon.

Exacerbating factors

 * Alcohol
 * Estrogen
 * Iron
 * Hepatitis C virus

Pathogenesis
Porphyria cutanea tarda is primarily caused by uroporphyrinogen decarboxylase deficiency (UROD). Uroporphyrinogen decarboxylase occurs in nature as a homodimer of two subunits. It participates in the fifth step in heme synthesis pathway, and is active in the cytosol. This enzymatic conversion results in coproporphyrinogen III as the primary product. This is accomplished by the clockwise removal of the four carboxyl groups present in the cyclic uroporphyrinogen III molecule. Therefore, a deficiency in this enzyme causes the aforementioned buildup of uroporphyrinogen and hepta-carboxylic porphyrinogen, and to a lesser extent hexa-carboxylic porphyrinogen, and penta-carboxylic porphyrinogen in the urine, which can be helpful in the diagnosis of this disorder.

The dermatological symptoms of PCT that include blistering and lesions on sun-exposed areas of the skin are caused by a buildup of porphyrin compounds (specifically uroporphyrinogen) close to the surface of the skin that have been oxidized by free radicals or sunlight. The oxidized porphyrins initiate degranulation of dermal mast cells, which release proteases that catabolize the surrounding proteins. This begins a cell-mediated positive feedback loop which matches the description of a type 4 delayed hypersensitivity reaction. The resulting blisters, therefore, do not appear immediately but begin to show up 2–3 days after sun exposure. Due to the highly conjugated structure of porphyrins involving alternating single and double carbon bonds, these compounds exhibit a deep purple color, resulting in the discoloration observed in the skin. Excess alcohol intake decreases hepcidin production which leads to increased iron absorption from the gut and an increase in oxidative stress. This oxidative stress then leads to inhibition of uroporphyrinogen decarboxylase, creating an excess of uroporphyrinogen III which is oxidized from the relatively harmless porphyrinogens into their oxidized porphyrins form. Concentrated instances of oxidative stress (alcohol, physical trauma, psychological stress, etc.) cause the liver to hemorrhage these porphyrins into the blood stream where they are then susceptible to oxidation.

The strong association of PCT with Hepatitis C virus infection is not entirely understood. Studies have suggested that the cytopathic effect of the virus on hepatocytes can lead to the release of free iron. This iron can disrupt the activity of cytochrome p450, releasing activated oxygen species. These can oxidize the UROD substrate uroporphyrinogen, which can result in the inhibition of UROD and lead to deficient activity of this key enzyme.

Excess alcohol use is frequently associated with both inducing PCT and aggravating a preexisting diagnosis of the disorder. It is thought to do so by causing oxidative damage to liver cells, resulting in oxidized species of uroporphyrinogen that inhibit the activity of hepatic UROD. It is also felt to increase the uptake of iron in liver cells, leading to further oxidation of uroporphyrinogen by the release of activated oxygen species. Additionally, exposure to chlorinated cyclic hydrocarbons can lead to a deficiency in the activity of uroporphyrinogen decarboxylase, causing the buildup of excess uroporphyrinogen. Additionally, alcohol has been shown to increase the activity of the delta-aminolevulinic acid synthetase (ALA synthetase), the rate-limiting enzymatic step in heme synthesis in the mitochondria, in rats. Therefore, alcohol consumption may increase the production of uroporphyrinogen, exacerbating symptoms in individuals with porphyria cutanea tarda.

Diagnosis
While the most common symptom of PCT is the appearance of skin lesions and blistering, their appearance is not conclusive. Laboratory testing commonly reveals high levels of uroporphyrinogen in the urine, clinically referred to as uroporphyrinogenuria. Additionally, testing for common risk factors such as hepatitis C and hemochromatosis is strongly suggested, as their high prevalence in patients with PCT may require additional treatment. If clinical appearance of PCT is present, but laboratories are negative, the diagnosis of pseudoporphyria should be seriously considered.

Classification
Some sources divide PCT into two types: sporadic and familial. Other sources include a third type, but this is less common.

One study used 74% as the cutoff for UROD activity, with those patients under that number being classified as type II, and those above classified as type III if there was a family history, and type I if there was not.

Genetic variants associated with hemochromatosis have been observed in PCT patients, which may help explain inherited PCT not associated with UROD.

Treatment
Since PCT is a chronic condition, a comprehensive management of the disease is the most effective means of treatment. Primarily, it is key that patients diagnosed with PCT avoid alcohol consumption, iron supplements, excess exposure to sunlight (especially in the summer), as well as estrogen and chlorinated cyclic hydrocarbons, all of which can potentially exacerbate the disorder. Additionally, the management of excess iron (due to the commonality of hemochromatosis in PCT patients) can be achieved through phlebotomy, whereby blood is systematically drained from the patient. A borderline iron deficiency has been found to have a protective effect by limiting heme synthesis. In the absence of iron, which is to be incorporated in the porphyrin formed in the last step of the synthesis, the mRNA of erythroid 5-aminolevulinate synthase (ALAS-2) is blocked by attachment of an iron-responsive element (IRE) binding cytosolic protein, and transcription of this key enzyme is inhibited.

Low doses of antimalarials can be used. Orally ingested chloroquine is completely absorbed in the gut and is preferentially concentrated in the liver, spleen, and kidneys. They work by removing excess porphyrins from the liver via increasing the excretion rate by forming a coordination complex with the iron center of the porphyrin as well as an intramolecular hydrogen bond between a propionate side chain of the porphyrin and the protonated quinuclidine nitrogen atom of either alkaloid. Due to the presence of the chlorine atom, the entire complex is more water-soluble allowing the kidneys to preferentially remove it from the blood stream and expel it through urination. Chloroquine treatment can induce porphyria attacks within the first couple of months of treatment due to the mass mobilization of porphyrins from the liver into the blood stream. Complete remission can be seen within 6–12 months as each dose of antimalarial can only remove a finite amount of porphyrins and there are generally decades of accumulation to be cleared. Originally, higher doses were used to treat the condition but are no longer recommended because of liver toxicity. Finally, due to the strong association between PCT and Hepatitis C, the treatment of Hepatitis C (if present) is vital to the effective treatment of PCT. Chloroquine, hydroxychloroquine, and venesection are typically employed in the management strategy.

Epidemiology
PCT prevalence is estimated at 1 in 10,000. An estimated 80% of porphyria cutanea tarda cases are sporadic. The exact frequency is not clear because many people with the condition never experience symptoms and those that do are often misdiagnosed with anything ranging from idiopathic photodermatitis and seasonal allergies to hives.

Society and culture
Porphyria cutanea tarda is implicated in the origin of vampire myths. This is because people with the disease tend to avoid the sun due to photosensitivity and may develop disfigurement that eats away their noses, eyelids, lips, and gums giving their teeth a fang-like appearance. It has also been suggested they may have developed a craving for healthy blood to replace their own in a self medicated treatment in prior centuries.

Some folklore scholars claim that this is a mistake, first suggested in the 1990s, because vampires of myth did not have photosensitivity, nor were they described as looking like the modern incarnation of vampires. They were described as unintelligent roaming beings who fed on their victims to the point that they became reddened and heavily bloated, fattened on blood. Fangs were very rarely mentioned. Photosensitivity was not added to the vampire mythology until the 1922 film Nosferatu. Count Dracula of Bram Stroker's novel could walk about freely in daylight unharmed but not as powerful in the book.

Porphyria cutanea tarda is the name of a song by the rock band AFI on their fourth album Black Sails in the Sunset, released on May 18, 1999.

Porphyria cutanea tarda is the disease that both Dabney Pratt and Brother Rush suffer from in Virginia Hamilton's children's novel Sweet Whispers, Brother Rush.

title: Porphyria cutanea tarda


text:
Erythropoietic protoporphyria

Erythropoietic protoporphyria (or commonly called EPP) is a form of porphyria, which varies in severity and can be very painful. It arises from a deficiency in the enzyme ferrochelatase, leading to abnormally high levels of protoporphyrin in the red blood cells (erythrocytes), plasma, skin, and liver. The severity varies significantly from individual to individual.

A clinically similar form of porphyria, known as X-Linked dominant protoporphyria, was identified in 2008.

Presentation
EPP usually presents in childhood with the most common mode of presentation as acute photosensitivity of the skin. It affects areas exposed to the sun and tends to be intractable. A few minutes of exposure to the sun induces pruritus, erythema, swelling and pain. Longer periods of exposure may induce second degree burns. After repetitive exposure, patients may present with lichenification, hypopigmentation, hyperpigmentation and scarring of the skin.

EPP usually first presents in childhood, and most often affects the face and the upper surfaces of the arms, hands, and feet and the exposed surfaces of the legs. Most patients, if the EPP is not as severe, manifest symptoms with onset of puberty when the male and female hormone levels elevate during sexual development and maintenance. More severe EPP can manifest in infancy. EPP can be triggered through exposure to sun even though the patient is behind glass. Even the UV emissions from arc welding with the use of full protective mask have been known to trigger EPP. EPP can also manifest between the ages of 3 and 6.

Prolonged exposure to the sun can lead to edema of the hands, face, and feet, rarely with blistering and petechiae. Skin thickening can sometimes occur over time.

People with EPP are also at increased risk to develop gallstones. One study has noted that EPP patients suffer from vitamin D deficiency.

Liver failure
Protoporphyrin accumulates to toxic levels in the liver in 5–20% of EPP patients, leading to liver failure. The spectrum of hepatobiliary disease associated with EPP is wide. It includes cholelithiasis, mild parenchymal liver disease, progressive hepatocellular disease and end-stage liver disease.

A lack of diagnostic markers for liver failure makes it difficult to predict which patients may experience liver failure, and the mechanism of liver failure is poorly understood. A retrospective European study identified 31 EPP patients receiving a liver transplant between 1983 and 2008, with phototoxic reactions in 25% of patients who were unprotected by surgical light filters. The same study noted a 69% recurrence of the disease in the grafted organ. Five UK liver transplants for EPP have been identified between 1987 and 2009. Frequent liver testing is recommended in EPP patients where no effective therapy has been identified to manage liver failure to date.

Pregnancy
EPP photosensitivity symptoms are reported to lessen in some female patients during pregnancy and menstruation, although this phenomenon is not consistent, and the mechanism is not understood.

Genetics
Most cases of EPP are results of inborn errors of metabolism but the metabolic defect in some patients may be acquired. Mutation of the gene that encodes for ferrochelatase in the long arm of chromosome 18 is found in majority of the cases. Ferrochelatase (FECH) catalyzes the insertion of ferrous iron into the protoporphyrin IX ring to form heme. EPP exhibits both recessive and dominant patterns of inheritance and a high degree of allelic heterogeneity with incomplete penetrance. Most heterozygotes are asymptomatic. Symptoms do not occur unless FECH activity is less than 30% of normal, but such low levels are not present in a majority of patients.

Pathophysiology
Cells which synthesize heme are predominantly erythroblasts/reticulocytes in the bone marrow (80%) and hepatocytes (20%). Deficiency of FECH results in increased release of protoporphyrin, which binds to albumin in plasma and subsequently undergoes hepatic extraction. Normally, most protoporphyrin in hepatocytes is secreted into bile; the remainder undergoes transformation into heme. Some protoporphyrin in bile is returned to the liver as a consequence of the enterohepatic circulation; the remaining protoporphyrin in the intestine undergoes fecal excretion. Protoporphyrin is insoluble and hence unavailable for renal excretion. In EPP, subnormal biotransformation of protoporphyrin into heme results in accumulation of protoporphyrin in hepatocytes.

Since FECH deficiency is associated with increased concentrations of protoporphyrin in erythrocytes, plasma, skin and liver, retention of protoporphyrin in skin predisposes to acute photosensitivity. As a result of absorption of ultraviolet and visible light (peak sensitivity at 400 nm, with lesser peaks between 500–625 nm ) by protoporphyrin in plasma and erythrocytes when blood circulates through the dermal vessels, free radicals are formed, erythrocytes become unstable and injury to the skin is induced.

A significant increase in the hepatobiliary excretion of protoporphyrin can damage the liver through both cholestatic phenomena and oxidative stress —predisposing to hepatobiliary disease of varying degrees of severity.

Diagnosis
EPP is generally suspected by the presence of acute photosensitivity of the skin and can be confirmed by detection of a plasmatic fluorescence peak at 634 nm. It is also useful to find increased levels of protoporphyrin in feces and the demonstration of an excess of free protoporphyrin in erythrocytes.

Screening for FECH mutation on one allele or aminolevulinic acid synthase 2 gain-of-function mutation in selected family members may be useful, especially in genetic counseling.

Liver biopsy confirms hepatic disease in EPP by the presence of protoporphyrin deposits in the hepatocytes that can be observed as a brown pigment within the biliary canaliculi and the portal macrophages. Macroscopically, the cirrhotic liver can have a black color due to protoporphyrin deposits. Using polarized light the characteristic Maltese cross shape of birefringent crystalline pigment deposits is found. The examination of liver tissue under a Wood’s lamp reveals a red fluorescence due to protoporphyrin. Liver biopsy is not helpful for estimation of prognosis of liver disease.

Treatment
There is no cure for this disorder; however, symptoms can usually be managed by limiting exposure to daytime sun and some types of artificial lighting. Most types of artificial lighting emit light in the problematic wavelengths, with fluorescent lighting being the worst offender. Color temperature can be a good indicator of what light is most detrimental, as the higher the color temperature, the more violet light (380–450 nm) is emitted. Incandescent and LED lighting in the soft white range (2700–3000 K) produce the least problematic light. Additionally, selecting lower wattage bulbs can reduce the overall output of light.

Since the photosensitivity results from light in the visible spectrum, most sunscreens are of little use (with the exception of non-nano zinc oxide which provides uniform protection between 290–400 nm and some protection up to 700 nm ). Sun protective clothing can also be very helpful, although clothing with UPF values are only rated based on their UV protection (up to 400 nm) and not on their protection from the visible spectrum. Some sun protective clothing manufacturers use zinc oxide in their fabrics, such as Coolibar's ZnO Suntect line, which will offer protection from visible light.

Window films which block UV and visible light up to 450 nm can provide relief from symptoms if applied to the patient's automobile and home windows. An example of such would be Madico Amber 81 which can protect through the 500 nm range.

Blue blocking screen protectors can help provide relief from symptoms caused by televisions, phones, tablets and computer screens.

EPP is considered one of the least severe of the porphyrias. Unless there is liver failure, it is not a life-threatening disease.

Approved therapies
Afamelanotide, developed by Australian-based Clinuvel Pharmaceuticals, was approved in Europe in December 2014 and in the United States in October 2019 for treatment or prevention of phototoxicity in adults with EPP.

Off-label therapies
Several drugs are used off label by patients with EPP:
 * Ursodeoxycholic acid is a bile acid that is administered to promote biliary secretion of protoporphyrin. Results of its use in EPP are controversial. However, it is known to alter the composition of bile, to protect hepatocytes from the cytotoxic effect of hydrophobic bile acids, and to stimulate biliary secretion by several distinct mechanisms.
 * Hematin appears to reduce excess protoporphyrin production in the bone marrow. It has been administered to patients with EPP (3–4 mg/kg iv) who develop a crisis after liver transplantation.
 * Plasmapheresis can also decrease the levels of protoporphyrin in plasma, however its use in treating acute episodes is controversial.
 * Cholestyramine is an orally administered resin which reduces circulating levels of protoporphyrin by binding to protoporphyrin in the intestine and, hence, interrupting the enterohepatic circulation. It is usually used in combination with other treatment approaches.
 * Activated carbon, like cholestyramine, binds to protoporphyrin in the intestine and prevents its absorption. It is cheap and readily available. It seems to be effective in reducing circulating protoporphyrin levels.

Bone marrow transplantation, liver transplantation, acetylcysteine, extracorporeal albumin dialysis, parenteral iron and transfusion of erythrocytes are alternative plans for treatment of EEP.

Over-the-counter drug
Some over-the-counter drugs may help:
 * Proferrin is an oral heme supplement which may work similarly to Hematin.
 * B. subtilis (a gram-positive soil probiotic) produces ferrochelatase, which may be able to convert some of the protoporphyrin in the intestine into heme.
 * Beta carotene, though a recent meta analysis of carotene treatment has called its effectiveness into question.

Experimental therapies
Bitopertin has been undergoing trials in Australia since 2022 with some success in allowing participants to spend more time in full sunlight without ill effects.

Home remedies
Although erythropoietic protoporphyria symptoms may be temporarily suppressed with cold temperatures, patients have found that this method may extend, or even intensify pain and discomfort. However, home treatments that increase blood flow to the affected areas, such as immersion in warm water with quick drying or warm dry compresses, may increase the rate of pain relief. This has been noted as particularly effective in the hands, forearms, and face, as areas of decreased blood flow may be exposed to the accumulation of protoporphyrins for an extended period.

Epidemiology
Case reports suggest that EPP is prevalent globally. The prevalence has been estimated somewhere between 1 in 75,000 and 1 in 200,000 however it has been noted that the prevalence of EPP may be increasing due to a better understanding of the disease and improved diagnosis. An estimated 5,000–10,000 individuals worldwide have EPP. EPP is considered the most common form of porphyria in children. The prevalence in Sweden has been published as 1:180,000.

History
Erythropoietic protoporphyria was first described in 1953 by Kosenow and Treibs and completed in 1960 by Magnus et al. at the St John's Institute of Dermatology in London.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Erythropoietic protoporphyria


text:
Submarine films

The submarine film is a subgenre of war film in which most of the plot revolves around a submarine below the ocean's surface. Films of this subgenre typically focus on a small but determined crew of submariners battling against enemy submarines or submarine-hunter ships, or against other problems ranging from disputes amongst the crew, threats of mutiny, life-threatening mechanical breakdowns, or the daily difficulties of living on a submarine.

The genre plays on the psychological tension of the submarine's crew and their unseen enemy, signified by a soundscape that may feature explosions, the ping of sonar, the creaking of the submarine's hull under extreme pressure, the alarm ordering the submarine to dive, and the threatening sound signatures of a destroyer's propeller or of an approaching torpedo.

Some 150 films have been made in the submarine genre between 1910 and 2010, variously depicting submarines in relatively realistic stories about World War I, World War II or the Cold War, or purely fictional and fantastic scenarios.

Characteristics
Submarine films have their own particular semantics and syntax, creating a film genre concerned specifically with submarine warfare. A distinctive element in this genre is the soundtrack, which attempts to bring home the emotional and dramatic nature of conflict under the sea. For example, in the 1981 Das Boot, the sound design works together with the hours-long film format to depict lengthy pursuit with depth charges, and as the critic Linda Maria Koldau writes,

"again and again, the mortal threat of the [ sonar ] ping, which signifies [the crew's] helpless exposure to the enemy."

Koldau identifies the basic syntactic structure of the submarine genre as "outside is bad, inside is good." The unseen outside means the enemy: this may be from nature, with elements such as water pressure threatening to crush the hull, sea monsters, or underwater rocks; or human opponents. Meanwhile, the inside of the submarine represents the human warmth and trust of the crew for each other and for their captain, their lives bound together by the situation. To this scenario can be added elements from within such as mutiny, fire, discord, or accidents including radiation leakage; and from outside such as water, terrorism, disease, and weapons, while the plot may feature sudden switches from being the hunter to being the hunted.

The soundscape may depict the creaking of the hull under pressure: as Koldau observes, this is both realistic and metaphoric, standing in for the fear and the responsibility on the shoulders of the crew. Stress may further be expressed in the acoustic signature of specifically submarine threats, such as the swelling sound of an approaching destroyer's propeller, the soft buzz of an enemy torpedo, or the submarine's own alarm ordering an immediate dive.

Another element of the soundscape less often remarked upon is simply silence, which can mean both safety (nothing is happening) and unseen danger, creating tension.

List of submarine movies
This is a list of movies, grouped by the era in which they were made, in which a submarine plays a significant role in the storyline. From 1910 to 2010, some 150 fictional films about submarines have been made. Many of these are set in World War I, World War II, or the Cold War; others depict relatively "authentic" terrorist scenarios.

Some movies depict historical events from actual battles or incidents, such as Above Us the Waves, a 1955 film which depicts the true story of the British Royal Navy's midget submarines attacks on the. Other submarine movies develop a fictional plot created using more or less realistic details of naval warfare, such as the film U-571, which tells the story of a fictional U-boat in World War II.

Other submarine films from the fantasy, science fiction or occasionally horror film genres depict entirely fictitious events, such as the various film versions of Jules Verne's novel 20,000 Leagues Under the Sea.

Set before World War I

 * Hearts in Bondage (1936) – directed by Lew Ayres
 * The Hunley (1999) – CSS Hunley attacks a U.S. Navy ship

Made before World War II

 * The Secret of the Submarine (1915) – US action-adventure silent serial directed by George L. Sargent depicting prevention of US submarine from falling into enemy hands
 * A Submarine Pirate (1915) – US heist-comedy-short directed by Charles Avery and Syd Chaplin, depicting waiter attempting to foil sea-heist of gold-filled cargo vessel by submarine
 * Civilization (1916) – US allegorical-drama directed by Reginald Barker, Thomas H. Ince, Raymond B. West, et al. depicting pacifist German Count's construction of submarine with order to sink ocean liner Lusitania presumably also carrying enemy munitions; a.k.a. La cruz de la humanidad, a.k.a. Civilização
 * The Little American (1917) – US action-drama directed by Cecil B. DeMille and Joseph Levering, depicting ship of young Americans returning to ancestral French home torpedoed by a German U-boat and witness to German brutality while imprisoned; a.k.a. A Pequena Americana, a.k.a. La petite américaine
 * On the Jump (1918) – US comedy directed by Raoul Walsh, depicting US reporter who joins Liberty Loan campaign before he must rescue his girlfriend and stolen secret fuel formula from German agent rendezvousing with a German U-boat
 * Patriotism (1918) – US mystery-drama directed by Raymond B. West, depicting search in Scotland for German agent sending vital information to German U-boat fleet off the Scottish coast
 * Behind the Door (1919) – US action-drama directed by Irvin Willat, depicting German-American naval officer who takes revenge against the German U-boat commander who brutalized his wife after sinking his ship; a.k.a. Detrás de la puerta
 * The False Faces (1919) – US espionage-drama directed by Irvin Willat, depicting a thief who becomes a reluctant US agent and infiltrates German U-boat to deliver vital enemy information; a.k.a. The Lone Wolf
 * The Isle of Conquest (1919) – US adventure-drama directed by Irvin Willat, based on Arthur Hornblow novel, about a man and woman marooned on a deserted isle after their ship is sunk by a German U-boat
 * Mare Nostrum (1926) – directed by Rex Ingram
 * Submarine (1928) – directed by Frank Capra
 * Men Without Women (1930) – fictional USS S-13
 * The Sea Ghost (1931) – a.k.a. U-67
 * A Woman of Experience (1931)
 * Morgenrot (1933)
 * Hell Below (1933) – USS AL-14
 * Dark Journey (1937) – UK adventure-thriller directed by Victor Saville
 * Submarine D-1 (1937)
 * Submarine Patrol (1938) – directed by John Ford
 *  (1939) – the Soviet film
 * The Spy in Black (1939) – a.k.a. U-Boat 29
 * Thunder Afloat (1939)

Made during World War II

 * Three Little Sew and Sews (1939) – US comedy short directed by Del Lord, depicting the Three Stooges as sailors working in a ships' tailor shop tricked into stealing a submarine by Nazi spies
 * 49th Parallel (1941) – a U-boat is sunk in Hudson's Bay, leaving the surviving crewmen stranded in northern Canada
 * U-Boote westwärts! (U-Boat, Course West!) (1941) – German war film promoting Kriegsmarine and Unterseeboot service
 * Crash Dive (1943) – fictional USS Corsair
 *  (1943) – the Soviet movie
 * Destination Tokyo (1943) – fictional USS Copperfin
 * Gung Ho (1943) – fictional account of the Makin Island raid
 * The Silver Fleet (1943) – British drama directed by Vernon Sewell and Gordon Wellesley, depicting a Dutch submarine builder forced to work for the Nazis
 * Submarine Alert (1943) – US thriller directed by Frank McDonald, depicting a former gangster supplying German U-boat commanders with torpedoes in South America
 * Submarine Base (1943) – US drama directed by Albert H. Kelley, depicting Nazi spies using a stolen shortwave transmitter prototype to broadcast top secret shipping info to an offshore Imperial Japanese Navy submarine
 * We Dive at Dawn (1943) – UK action-drama directed by Anthony Asquith, depicting fictional submarine HMS Sea Tiger on a mission to sink fictional German battleship Brandenburg
 * Two-Man Submarine (1944) – US B-movie directed by Lew Landers

Later films depicting World War II

 * The Damned (1947) – directed by René Clément
 * Morning Departure (1950) – directed by Roy Ward Baker. A British film about a crew aboard a disabled submarine during a rescue operation.
 * Mystery Submarine (1950) – directed by Douglas Sirk, depicting a mission to destroy a U-boat off the coast of South America; a.k.a. Phantom Submarine
 * Operation Pacific (1951) – fictional USS Thunderfish
 * Submarine Command (1951) – US drama directed by John Farrow, depicting a US submarine commander forced to confront the consequences of sudden high-sea submersion while the crew remain outside the submarine
 * Ubåt 39 (U-Boat 39) (1952) – Swedish drama directed by Hampe Faustman, depicting the crew of GS U-39 (1938)
 * Torpedo Alley (1953) – US drama directed by Lew Landers, depicting a US Navy pilot rescued at sea by submarine before applying for submarine duty; a.k.a. Down Periscope
 * Submarine Attack (La grande speranza) (1954) – Italian action-romance directed by Duilio Coletti, depicting an Italian submarine sinking Allied shipping during the Battle of the Atlantic; a.k.a. Torpedo Zone
 * Above Us the Waves (1955) – Royal Navy midget submarines vs. German battleship Tirpitz
 * Hellcats of the Navy (1957) – fictional USS Starfish
 * Sea Wife (1957) – US action-drama directed by Bob McNaught and starring Richard Burton and Joan Collins, depicting a cargo ship dangerously jammed to excess capacity with evacuees fleeing the 1942 Japanese invasion and Battle of Singapore that is sunk by a Japanese Imperial Navy submarine; one scene depicts the submarine underwater while another scene shows the submarine on the surface
 * The Enemy Below (1957) – US action-drama directed by Dick Powell, depicting a duel between an American destroyer escort and a German U-boat in South Atlantic
 * Run Silent, Run Deep (1958) – fictional USS Nerka (which loosely shares plot elements and the villain destroyer captain, Bungo Pete, with Edward L. Beach's novel, but not much of the plot)
 * Submarine Seahawk (1958) – US action-drama directed by Spencer Gordon Bennet depicting a US submarine commander on a reconnaissance mission to locate a fleet of Imperial Japanese Navy fighting ships; a.k.a. Submarine X-2
 * Torpedo Run (1958) – US drama directed by Joseph Pevney, depicting a US submarine commander confronted with destroying an Imperial Japanese Navy ship with Allied prisoners and civilians
 * U 47 – Kapitänleutnant Prien (1958) – somewhat factual combat career of Günther Prien
 * Battle of the Coral Sea (1959) – USS Dragonfish
 * Operation Petticoat (1959) – US comedy directed by Blake Edwards, depicting fictional USS Sea Tiger; remade in 1977 TV series Operation Petticoat
 * Orzeł (The Eagle) (1959) – Polish drama directed by Leonard Buczkowski, depicting ORP Orzeł and Orzeł incident
 * Up Periscope (1959) – US drama directed by Gordon Douglas, depicting a US Navy frogman on mission aboard a submarine to be smuggled into Japanese-held island; a.k.a. Up Periscope!
 * Nacht fiel über Gotenhafen (Darkness Fell on Gotenhafen) (1960) – German film about the sinking of the Wilhelm Gustloff by the Soviet submarine S-13. The film is about the maritime disaster, not about the submarine.
 * McHale's Navy (TV series), McHale and His Schweinhunds [Season 2, Episode 3] (1963) – US comedy episode directed by Sidney Lanfield, depicting a PT boat crew destroying a German U-boat rendezvousing with a Japanese patrol
 * Mystery Submarine (1963) – UK action-drama directed by C.M. Pennington-Richards, depicting a British captured U-boat used for a mission
 * Beta Som (Torpedo Bay) (1963) – Italian-French drama directed by Charles Frend and Bruno Vailati, depicting a British warship and Italian submarine operating in the Strait of Gibraltar and meeting in the neutral Rick's Cafe; a.k.a. Défi à Gibraltar
 * Morituri (1965) – US drama directed by Bernhard Wicki, depicting German blackmailed by English to impersonate SS officer aboard ship; a.k.a. Saboteur: Code Name Morituri
 * McHale's Navy (TV series), 36-24-73 [Season 4, Episode 23] (1966) – US comedy episode directed by Hollingsworth Morse, depicting a PT boat crew capturing a German U-boat
 * Submarine X-1 (1969) – X class submarines
 * Murphy's War (1971)
 * Commander of the Lucky 'Pike' (1972), the Soviet movie
 * Operation Petticoat (TV series) (1977–79) – comedy directed by Hollingsworth Morse, depicting fictional USS Sea Tiger; spinoff of 1959 film Operation Petticoat, producing 32 episodes
 * 1941 (1979) – US comedy directed by Steven Spielberg, depicting an Imperial Japanese Navy submarine terrorizing the California coast
 * Das Boot (1981) – German movie about GS U-96 (1940)
 *  (1985), the Soviet film, about S-131
 *  (1985), the Soviet TV-movie
 *  (1986–87), the Soviet TV miniseries
 * 'War and Remembrance' (TV miniseries) (1988)
 * Das letzte U-Boot (The Last U-Boat) (1993) – a German television film about U-234
 * 'U-571' (2000) – fictional GS U-571
 * Below (2002) – fictional USS Tiger Shark (horror)
 * In Enemy Hands (2004) – fictional USS Swordfish and U-429; a.k.a. U-Boat
 * Ghostboat (2006) – mystery-thriller based on George E. Simpson and Neal R. Burger novel, directed by Stuart Orme, depicting fictional HMS Scorpion lost during World War II and resurfacing near the end of the Cold War
 * 真夏のオリオン (Battle under Orion) (2009) – Japanese action-drama directed by Tetsuo Shinohara, depicting an Imperial Japanese Navy submarine against a US destroyer near the end of the war; a.k.a. Manatsu no Orion, Last Operations Under the Orion
 * Die Gustloff (2008) – German television drama about the sinking of the Wilhelm Gustloff. Really the story of the maritime disaster, but does feature a few scenes aboard the Soviet submarine S-13
 * The Sinking of the Laconia (2010) – British-German historical drama directed by Uwe Janson about the sinking of the former British ocean liner RMS Laconia by GS U-156 (1941), which then, with three other U-boats (including GS U-507) and an Italian submarine, attempted to rescue nearly 2,000 passengers
 * Torpedo (Also known as U-235) – a Belgian film (2019)

Korean War

 * Submarine Command (1951) – fictional USS Tiger Shark

Cold War

 * Morning Departure (1950) – British drama directed by Roy Ward Baker depicting the crew of a sunken British submarine trapped on the sea floor; a.k.a. Operation Disaster
 * Hell and High Water (1954) – American action-adventure directed by Samuel Fuller, depicting a World War II surplus Japanese submarine battling a Chinese submarine
 * On the Beach (1959) – fictional nuclear submarine USS Sawfish (SSN-623)
 * Voyage to the Bottom of the Sea (1961) – adventure-science fiction film directed by Irwin Allen, depicting fictional SSRN Seaview; remade in the 1964 TV series Voyage to the Bottom of the Sea
 * Voyage to the Bottom of the Sea (TV series) (1964) – adventure-science fiction, directed by Jus Addiss depicting fictional SSRN Seaview; spinoff of 1961 film Voyage to the Bottom of the Sea
 * The Bedford Incident (1965)
 * The Russians Are Coming, the Russians Are Coming (1966) – American comedy directed by Norman Jewison, depicting fictional Soviet submarine Спрут; a.k.a. The Russians Are Coming! The Russians Are Coming!
 * Ice Station Zebra (1968) – fictional USS Tigerfish (SSN-509) (in novel: USS Dolphin)
 * Mission Impossible (TV series), "Submarine" (1969) – American action-adventure episode directed by Paul Krasny, depicting former SS officer with plans to fund Neo-Nazis
 * The Boatniks (1970) – comedy directed by Norman Tokar, depicting a salami in a submarine torpedo tube
 * Assault on the Wayne (1971) – fictional missile submarine USS Wayne (also named in The Spy Who Loved Me)
 * The Spy Who Loved Me (1977) – American, British and Soviet submarines
 * Gray Lady Down (1978) – fictional USS Neptune
 * Bear Island (1979) – fictional U.S. Science Year team on remote island discover a World War II submarine base to which the SS had dispatched two U-boats with holds full of gold bullion from the conquest of Europe. SS, ex-Nazis, sons of U-boat commanders, Israelis, all try to recover the enormous wealth.
 * Raise the Titanic (1980) – U.S. submarine confronts a Soviet warship and escorts the salvaged Titanic to port
 * Virus (1980 film) (1980) – fictional HMS Nereid
 * Incident at Map Grid 36-80 (1982) – the Soviet movie, about U.S. submarine
 * Never Say Never Again (1983) – fictional U.S. submarine
 * The Fifth Missile (1986) – fictional USS Montana
 * The Dolphin's Cry (1986) – the Soviet movie
 * Russkies (1987) – the Soviet submarine
 * Full Fathom Five (1990) – fictional USS Aspen versus Alpha Victor Three class submarine CCCP ''Kirov'
 * The Rift (1990) – fictional Siren II searches for lost Siren I
 * The Hunt for Red October (1990) – fictional Red October (Красный Октябрь), fictional V.K. Konovalov (В. К. Коновалов), USS Dallas (SSN-700), DSRV-1 Mystic
 * Going Under (1991) – Comedy – An American submarine races to get a nuclear weapon before a Russian submarine.
 * Buried on Sunday (1992) – a Soviet submarine is used to launch a missile attack on Canada's Wonderland
 * Silent Service (1995) – anime; JMSDF Seabat (Japan's first nuclear-powered submarine)
 * Hostile Waters (1997) – K-219
 * K-19: The Widowmaker (2002) – K-19
 * Phantom (2013) – K-129, the plot has a basis in one theory about the events aboard the Soviet submarine's final voyage

Post-Cold War

 * Crimson Tide (1995) – USS Alabama (SSBN-731)
 * Down Periscope (1996) – comedy directed by David S. Ward, depicting fictional USS Stingray (SS-161)
 * Peculiarities of the National Fishing (1998)
 * Phantom: The Submarine (1999), about fictional South Korea's first nuclear-powered submarine Phantom.
 * On the Beach (2000) – fictional Los Angeles-class submarine USS Charleston (SSN-704)
 * Danger Beneath the Sea (2001)
 * 72 Meters (2004)
 * Phantom Below (2005)
 * Last Resort (2012–13) – TV series, fictional Ohio-class submarine, USS Colorado (SSBN-753)
 * Black Sea (2014)
 * Hunter Killer (2018)
 * Kursk (2018)
 * The Wolf's Call (2019)

Other conflicts

 * Ghazi Shaheed (1998)
 * The Ghazi Attack (2017), first Indian underwater/war-at-sea film

Future or fantastic past

 * Le voyage à travers l'impossible (An Impossible Voyage) (1904) – French adventure-comedy silent short directed by Georges Méliès, depicting Geographic Society members on an around-the-world journey using various modes of transport including a submarine; a.k.a. The Voyage Across the Impossible, a.k.a. The Impossible Voyage; predecessor to 1907 silent film 20,000 lieues sous les mers
 * Twenty Thousand Leagues Under the Seas (1907, 1916, 1954, 1997, 1997) – Jules Verne's fictional Nautilus (science fiction/fantasy)
 * The Secret of Two Oceans (1957) – based on Grigory Adamov's novel, about the crew of the Soviet submarine "Pioneer"
 * The Atomic Submarine (1959) – fictional USS Tiger Shark battles an underwater alien spacecraft/submarine
 * Voyage to the Bottom of the Sea (1961) – Seaview nuclear submarine, the film was followed by a TV series 1964–68
 * The Fabulous World of Jules Verne (1958) – based on Jules Verne's Facing the Flag, featuring HMS Sword
 * The Three Stooges in Orbit (1962) – comedy directed by Edward Bernds, depicting the Three Stooges assisting an inventor with a new military hybrid (tank, helicopter, submarine) vehicle to aid in defense of a Martian invasion
 * Atragon (1963) – fictional Gotengo (science fiction/fantasy)
 * Stingray (1964–1965) – adventures of the WASPs (the World Aquanaut Security Patrol) (Supermarionation)
 * Fantastic Voyage (1966) – set in the near future, an experimental submarine with special medical team aboard are reduced to microscopic size and injected into body of a brain-damaged scientist possessing military secrets in an attempt to repair his injury
 * Around the World Under the Sea (1966)
 * Yellow Submarine (1968) – (psychedelic animated fantasy)
 * Captain Nemo and the Underwater City (1969) – Jules Verne's fictional Nautilus (science fiction/fantasy)
 * The Neptune Factor (1973) – undersea rescue (science fiction)
 * The Land That Time Forgot (1975) – depicts a stranded World War I U-boat crew on uncharted South-Atlantic sub-continent of "Caprona"
 * The Return of Captain Nemo (1978) – Jules Verne's fictional Nautilus (science fiction/fantasy)
 * Thundersub (1979) – (anime)
 * Virus (1980) – Japanese-made post-apocalyptic thriller featuring an international cast aboard a British sub, trying to find a cure to a global pandemic.
 * The Abyss (1989) – fictional USS Montana (science fiction/fantasy)
 * Nadia: The Secret of Blue Water (1989) – Jules Verne's fictional Nautilus (anime)
 * seaQuest DSV (1993) – (science fiction/fantasy)
 * Blue Submarine No. 6 (1998) – (anime)
 * The League of Extraordinary Gentlemen (2003) – Jules Verne's fictional Nautilus (fantasy)
 * Submarine 707R (2004) – (anime)
 * The Life Aquatic with Steve Zissou (2004) – US adventure-comedy-drama directed by Wes Anderson
 * Lorelei: The Witch of the Pacific Ocean (2005) – (World War II, science fiction)
 * Tide-Line Blue (2005) – (anime)
 * The Land That Time Forgot (2009) – action-sci-fi directed by C. Thomas Howell, depicting a stranded World War II U-boat crew in a time void on an island inside the Bermuda Triangle
 * Arpeggio of Blue Steel (2013) – (anime)

title: Submarine films


text: Template:Casablanca class escort carrier


text:
Talk:Star system

Show biz etc
Because of the use of the term 'Star System' in both show-business and astronomy/astrophysics, does this page need to be made into a disambiguation page? There's at least one astronomy page linked to this one (Proxima Centauri). --rparle 01:41, Mar 11, 2004 (UTC)

 * As the stubby article indicates, I don't think there's a whole lot of encyclopedic content to write about "star system" in the showbiz context, and it doesn't seem like people would instinctively link to it. I've cleaned out most of the links and redirected to Constellation. I'm no expert, and more informed individuals are welcome to change this if a star system is considered a distinctly different concept. --Michael Snow 22:27, 17 Mar 2004 (UTC)

Constellation and Star System are not at all the same thing, but we have no content for the star system article yet. Best option is to blank/delete it until someone wants to write it. --rparle 23:38, Mar 17, 2004 (UTC)

 * I think we can leave the redirect, even if they're not the same thing. Then if someone uses the link and objects to the redirection, maybe that will motivate them to write the article. --Michael Snow 00:00, 18 Mar 2004 (UTC)

 * I would argue that a misleading redirect is worse than none at all, because it could be confusing. I've replaced the redirect with a short article, although I'm not an expert in the area.  Wmahan 22:55, 24 Mar 2004 (UTC)

Star system, stellar system, solar system, planetary system ...
Hello! I've noted recent statements about why this distinction has been so characterised; however (perhaps I'm missing this), I do not see any cited references (particularly from astronomical references) substantiating these distinctions. Please corroborate and verify. Thanks! E Pluribus Anthony 09:18, 1 November 2005 (UTC)

Hello again! Further to my prior request (unanswered) and after some digging, my search for authoritative definitions for some of these terms has born some fruit:

EXCELLENT! Cameronbassir (talk) 17:17, 21 March 2018 (UTC)Cameronbassir
 * solar system - this is pretty clear-cut:

 * Solar System –  A group of celestial bodies comprising the Sun and the large number of bodies that are bound gravitationally to the Sun and revolve in approximately elliptical orbits around it....
 * — Collins Dictionary of Astronomy (ISBN 0-00-710297-6), p. 382

 * ''Solar System –  The collective name for the Sun and all the bodies that orbit it.  It includes the nine major planets and over 100 known satellites, plus countless asteroids, comets, and meteoroids....
 * — Oxford Dictionary of Astronomy (ISBN 0-19-860513-7), p. 420

 * Such dictionary definitions neglect the effect of popular usage of the term "solar system", and thus we should also grandfather in popular usages of the term as well. —  Rickyrab | Talk 18:01, 23 August 2006 (UTC)

 * No real argument: it appears the definitions were researched and provided to promote clarity (particularly given the various terms), not necessarily to indicate popular usage or if the term should be capitalised per se. Indeed, the Oxford English Dictionary, Merriam-Webster's 11th Collegiate Dictionary, and Encyclopaedia Britannica render the term solely in lower case. Cogito ergo sumo 21:05, 4 September 2006 (UTC)

 * stellar system –  "A gravitational system of stars."
 * — The McGraw Hill Dictionary of Astronomy (ISBN 0071410473), p. 125

 * This definition implies it can be correctly used for systems with more than one star, e.g., binary systems, with their constituents. Whether it can be used for one star alone and associated bodies is not wholly clear, in which case star system is likely more appropriate; however, a logical assumption can also be made that stellar, being an adjectival form of star (or stars, as per Oxford English Dictionary), can be used in a similar way to solar when referring to the Sun (Sol), e.g., (unitary) star system.

 * It cannot be one star and associated non-stellar bodies. The definition says stars. Plural. Nurg 03:12, 1 October 2006 (UTC)

 * Hmmm: given parallels with our own star system and until more authoritative sourcing/definitions can be provided, unequivocal statements and related edits asserting this viewpoint seem somewhat unjustified. Cogito ergo sumo 14:23, 1 October 2006 (UTC)

 * Current definition is "a system comprised of a star or group of stars, and, perhaps, planetary systems of smaller bodies (such as planets or asteroids". So it can be (a) a star alone (b) a star with planets etc. (c) group of stars of unlimited number without planets etc. (d) group of stars of unlimited number with planets etc. So it covers everything from a star alone to a galaxy. Where do I find the article dealing with the narrower topic of two or several stars bound by their mutual gravitational attraction such as binary stars, triple star systems etc? Up till Nov 2005 it was this article and the definition was "a group of stars (and possibly smaller bodies such as planets or asteroids) that orbit one another ... a group of a small number of stars, often two or three". The changes to the definition by E Pluribus Anthony on 6 Nov 2005 were well-intentioned but unfortunate, I'm afraid. Credit to E Pluribus Anthony for explaining his thinking on this Talk page because we can see that he based the changes in part on his interpretation of the Mcgraw definition to possibly allow for a single star and associated bodies even though it said "stars" and did not mention associated bodies! Nurg 10:26, 2 October 2006 (UTC)

 * It appears that changes to this and related articles by E Pluribus Anthony were well-intentioned and necessary: there appeared to be much unsourced confusion regarding applicable definitions. Thus, I'm actually unsure what the problem is here and disagree with your recent edits.  Yes, I think the current definition does legitimately allow for a wide range of phenomena: from a unitary star system (e.g., Solar System) – which seems to also be a basis for those changes, and not an illogical one – to multiples, and up to galaxies (which your definition below seems to indicate).  I mean, really, that's what a system of entities is.  And, not to sound obvious, but I think you'd have to consult the respective articles about binary stars, triple star systems, et al. for more specificity and additional information on those topics. Cogito ergo sumo 10:42, 2 October 2006 (UTC)

 * star system –  Strangely, I could not (yet) find printed references/definitions for this term; see solar system and stellar system

 * Here's one. "a group of stars thought of collectively; a galaxy." Source: star system. Chambers 21st Century Dictionary (2001). Retrieved 01 October 2006. Available from xreferplus. http://www.xreferplus.com/entry/1230254. Again that's stars plural. Nurg 03:12, 1 October 2006 (UTC)

 * This is a limited-access reference source; otherwise, as above. Cogito ergo sumo 14:23, 1 October 2006 (UTC)

 * Chambers 21st is available on paper. ISBNs 055014210X and 0550142509.

 * Star system. "a few stars that orbit each other. For example, a double star system consists of two stars; a triple star system consists of three stars; and so on." Source: "star system" in Modern Dictionary of Astronomy and Space Technology. ed. A.S. Bhatia. New Delhi: Deep & Deep Publications, 2005. ISBN 8176297410. Nurg 00:10, 7 October 2006 (UTC)

 * planetary system –  ... A system of celestial bodies in orbit around a star including planets, moons, asteroids, comets, and dust.
 * — The Universal Book of Astronomy, from the Andromeda Galaxy to the Zone of Avoidance (ISBN 0471265691), p. 394

 * ... A system of planets and other bodies, such as comets and meteroids, that orbits a star.   The Sun and its planetary system together comprise the solar system.
 * — Collins, p. 314

 * Note the distinction between solar and planetary system, viz. the Sun (or central star). This clearly does not include the central star(s) as part of the system, so references to the stars and their planets (in an extrasolar context, in toto) can more correctly be dubbed as star system or stellar system, and even improperly, as 'solar system' (e.g., as commonly referred to, like in Serenity).

In some respects, some of these clearly differ with definitions and interpretations already presented in the appropriate Wp articles. Based on this information and unless there are reputable opinions/citations to the contrary, I will be making these appropriate editions to the relevant articles. Thanks! E Pluribus Anthony 01:21, 6 November 2005 (UTC)

Citations regarding 'star system'
User:Nurg has recently added a citation flag to the current definition regarding 'star system' and its applicability to (a system having) just one star. Considering the above (including apparent contraindications in defintions) and particularly regarding usage of the term, I believe this is unjustified; for example:
 * : note title, which details the discovery of planets around a single star (system)
 * : usage regarding our own Sun
 * : discussion of habitable star systems: if one considers only multiple star systems to be potentially habitable (which is highly improbable, methinks, given gravitational forces/instability within them, as opposed to single star systems), then this article is arguably moot or irrelevant ... but I don't think so

Similarly, perhaps most importantly, the example of our own single star system -- the Solar System -- cannot be ignored.

As such, I am removing the citation tag. Cogito ergo sumo 11:13, 3 October 2006 (UTC)

 * Re the first link - that title was probably written by an editor at the popular science site. The article itself consistently uses the term "planetary system" and does not use "star system" once. The original article at ESO has the completely different title "Trio of Neptunes and their Belt".

 * Re the 2nd link - that is a directory of links and has no value in itself. It links to "The Sun: An Introduction to the Stars" which contains a single reference to "a single star system" but provides no definition and is ambiguous as to whether it means a "single-star star system" or a single (multiple-star) star system.

 * Re the 3rd link - doesn't define "star system" and is not conclusive.

 * Re the Wikipedia Solar System article. The definition of the Solar System as a stellar system is unreferenced and may be challenged. Nurg 00:10, 7 October 2006 (UTC)

Definitions - summary so far

 * Star system: "a few stars that orbit each other. For example, a double star system consists of two stars; a triple star system consists of three stars; and so on." Source: Modern Dictionary of Astronomy and Space Technology

 * Stellar system: "A gravitational system of stars." Source: The McGraw Hill Dictionary of Astronomy

 * Star system: "a group of stars thought of collectively". Source: Chambers 21st Century Dictionary

Nurg 00:10, 7 October 2006 (UTC)

 * Thanks for the research. I acknowledge the definitions above, which may require editions to relevant content.  However, one cannot dismiss usage as above or the parallel with the Solar System (as you have)/solar-stellar, either, and the implication that the term may apply just as well to a single (single-star) star system.  I believe more information or editorial opinion is required before making wholesale changes as proposed.  Cogito ergo sumo 13:56, 7 October 2006 (UTC)

Thanks Cogito. Part of our problem is that people can take common words like system, single and star/stellar and string them together but mean different things. So, depending on the context, "single star system" could mean "single-star planetary system" (eg, Solar System), "single multiple-star star system" or "single-star something-else system". My approach to defining Wikipedia articles is, in order:
 * 1) What is the topic and scope of the article? This is primary because we are writing about things and ideas, not about terms and their definitions which is what Wiktionary does.
 * 2) Having decided on a topic, what is the best name for the article?
 * 3) How do we define the name in the context of the topic? The article does not have to cover every possible meaning of the article name - that again is what Wiktionary does.

Applying these principles to this article:
 * 1) Up till Nov 2005 the scope of this article was "a group of stars (and possibly smaller bodies such as planets or asteroids) that orbit one another ... a group of a small number of stars, often two or three". Seems good and the bulk of the article still matches this.
 * 2) Given the topic, star system seems like a good name for it.
 * 3) The definition till Nov 2005 seems a fair, but perhaps not perfect, definition. The Modern Dictionary of Astronomy and Space Technology provides verification.

The addition of "a star" to the article definition doesn't make much sense. A star alone is covered by the star article obviously. A system of planets etc orbiting a single star is covered by the planetary system article.

What type of further information do you think is required? Nurg 00:56, 8 October 2006 (UTC)

 * I agree that there might be a problem -- however, I generally agree with the changes made since Nov./05 and still do. Moreover, your above analysis et al. is not necessarily agreeable and glazes over usage of the term, which is no less valid or verifiable, than cited definitions which seem (IMO) incomplete and minimalist.  For instance, an online search will reveal a number of instances of "single(-)star system" and I think it somewhat difficult to demonstrate they they too are incorrect.  Even if those are discarded, applying this notion merely to systems with two or more stars (double, trinary) to the exclusion of single-star 'entities' with non-stellar bodies in association (e.g., the Solar System) seems rather illogical.  If anything, the multiple contexts you've indicated above are reasons enough for the content to be included in this article.  Alternatively, the current scope of the article and definition/content is appropriate to the topic.

 * Thus, I defer to my prior comments: until there is overwhelming evidence to support your position (and I yet do not see it, though can be convinced otherwise) or additional editorial comment, I see little reason to change the status quo. Cogito ergo sumo 03:17, 8 October 2006 (UTC)

The main problem, as I see it, is that there isn't yet an agreed term for an extrasolar solar system. I think this article should focus on the agreed definition of "stellar system" (that is, multiple star systems), and that the articles for "planetary system", "solar system" and "extrasolar planet" should note that a generic term for what we call the solar system has yet to be fully settled. Serendipodous 13:34, 8 October 2006 (UTC)

 * Hmmm; while I do not disagree, I think you've crystallised the problem: definitions may agree, but usage (and verifiable at that) may not -- i.e., the cited definitions appear not to fully coincide with or prescribe usage of said terms. If articles are to be revised, they must be in a manner that embraces both perspectives. Cogito ergo sumo 13:56, 8 October 2006 (UTC)

 * A helpful researcher over on an astronomy forum I frequent did a search of Harvard academic papers for the term "stellar system". The most frequent usage was for "two or three stars bound together gravitationally == multiple star", and "large cluster of stars bound together gravitationally == galaxy or globular cluster." Serendipodous 21:22, 8 October 2006 (UTC)

 * If this is to be believed, "most frequent" is not exclusively. Again, I defer to prior comments ... Cogito ergo sumo 23:17, 8 October 2006 (UTC)

 * "solar system" does seem to be the most prevalent term for an "extrasolar" star and its gravitationally bound bodies in popularly abstracted image of such a thing as consisting of a single star. It makes me die a little on the inside, but it's understandable that it should end up this way. It's like calling other planets "other earths" instead of by proper names or as other PLANETS but I'm grateful at least we have that as an example I can make. Perhaps "solar system" needs a disambiguation page? Horrible. Antireconciler (talk) 17:42, 8 October 2014 (UTC)

As the "Solar System" refers to the system of Sol (the Sun), would it then not follow that because Sol is a star, the Solar System is an instance of a stellar system? This would then imply that a stellar system would comprise a star system and a planetary system. If so, we should not equate "star system" with "stellar system", and "stellar system" should have its own article. LordOfPens (talk) 05:47, 22 April 2020 (UTC)

Multiple Extreme example
This page claims Nu Scorpii has "at least seven stars", but the actual Nu Scorpii page mentions only a pair of close binaries with one being a spectroscopic double, for a total of 5 stars. I've replaced Nu Scorpii with castor, which is a sextuple system, and better known. CFLeon 04:49, 30 August 2006 (UTC)
 * There are even more complex systems.--JyriL talk 17:35, 30 December 2006 (UTC)
 * Unless citable, CFLeon's replacement was a good one. As much as I've read, there are no septuples known yet (for sure). ... said: Rursus (bork²) 22:27, 28 March 2009 (UTC)
 * According to this link and this one there are 2 septuples known. L8R. ... said: Rursus ( m bork³ ) 12:02, 27 August 2009 (UTC)
 * I found a typo in the link looking up ν Sco in MSC/Tokovinin. The SIMBAD version says the two known septuple systems are Nu Scorpii and AR Cassiopeiae, so it's time to reintroduce septuples in the table. ... said: Rursus ( m bork³ ) 12:24, 27 August 2009 (UTC)

Merge from triple star system
I can't see any reason why we should have separate article for triple star systems.--JyriL talk 17:35, 30 December 2006 (UTC)

Dubious
91 Aquarii is listed as a quintuple system, probably it is an obsolete theory, or a major confusion somehow, when following diverse links i find four or five star systems with at most three components, see Talk:91_Aquarii. ... said: Rursus ( m bork³ ) 18:49, 8 December 2009 (UTC)

Hextuples
Alcor/ Mizar are now considered bound together which makes the Alcor binary and the Mizar quadruple add up to a hextuple. http://arxiv.org/pdf/0911.5028 (Astrophysical Journal) Aidan Karley (talk) 12:15, 16 March 2010 (UTC)

Designations / Naming COnventions
Not mentioned in this article, would be useful to understand the nomenclature for star systems. For example, Alpha Centauri is a triple star system, the individual stars are Alpha Centauri A, Alpha Centauri B and Alpha Centauri C, however the system is referred to as Alpha Centauri or Alpha Centauri AB - the reason for this is not entirely clear just looking at this article. Perhaps this article could describe the conventions used and how they are determined based on how stars are gravitationally bound. --EvenGreenerFish (talk) 07:14, 21 December 2011 (UTC)
 * I believe that Alpha Centauri AB and Proxima Centauri are referred to separately for a few reasons - firstly, the fact that they were historically given those names, and secondly, because Proxima is still only a "very likely" member of the system, rather than being 100% verified. You can see historical "artifact titles" at work a number of systems; for example, the two stars of the Zeta Reticuli system still use their old double star designations, Zeta1 and Zeta2, because they were first thought to be an optical double that wasn't physically associated (rather than members of a wide binary, as we know them to be today). --203.57.209.105 (talk) 03:44, 28 September 2014 (UTC)

Stability of (a) in the diagram
Wouldn't (a) in the diagram necessarily have to be unstable? --JorisvS (talk) 09:01, 11 February 2014 (UTC)

Frequencies of multiples
What are the frequencies of double, triple, etc. systems relative to single stars? --JorisvS (talk) 14:18, 11 February 2014 (UTC)

Dubious - Mintaka/Delta Orionis
Every source I can find online says that Mintaka is a four-star system, with an OII and a BV star pair forming an Algol-type eclipsing binary, and two distant companions (which seem to be mostly unstudied, but one source has the brighter of the two as a B-type star of some sort). However, it's listed as a quintuple system here, with no citation. Unless someone can back this up, I'm going to go ahead and change it. --203.57.209.105 (talk) 03:35, 28 September 2014 (UTC)

External links modified (January 2018)
Hello fellow Wikipedians,

I have just modified 4 external links on Star system. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:
 * Added tag to http://eaa.iop.org/
 * Added archive https://web.archive.org/web/20060919155603/http://www.ctio.noao.edu/~atokovin/papers/dynamics.pdf to http://www.ctio.noao.edu/~atokovin/papers/dynamics.pdf
 * Added archive https://web.archive.org/web/20080412092018/http://ad.usno.navy.mil/wds/wdsweb_format.txt to http://ad.usno.navy.mil/wds/wdsweb_format.txt
 * Added archive https://web.archive.org/web/20110615045153/http://www.ctio.noao.edu/~atokovin/stars/index.php?cat=HD&number=120955 to http://www.ctio.noao.edu/~atokovin/stars/index.php?cat=HD&number=120955
 * Added archive https://web.archive.org/web/20170905183433/http://www.ctio.noao.edu/~atokovin/stars/index.php?cat=HD&number=145501 to http://www.ctio.noao.edu/~atokovin/stars/index.php?cat=HD&number=145501

When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.

Cheers.— InternetArchiveBot  (Report bug) 23:37, 21 January 2018 (UTC)

Discussion affecting this WikiProject - The Sun
There is a discussion about whether should redirect to  or to. THe discussion is at Redirects for discussion/Log/2018 July 25. The editor  whose username is Z0 06:53, 27 July 2018 (UTC)

Error in the introduction?
"If there are no tidal effects, no perturbation from other forces, and no transfer of mass from one star to the other, such a system is stable, and both stars will trace out an elliptical orbit around the barycenter of the system indefinitely" I'm not an astrophysicist, but don't binary systems lose energy via gravitational radiation, and therefore eventually spiral into the barycentre? I appreciate it would be very slow, but it's not indefinite is it?

 * Yes. Also Future_of_an_expanding_universe also says that (star) matter will decay (and escape) or turn into black holes and evaporate via Hawking radiation. That level of nitpicking may not be reasonable in an introduction, though. That's like trying to tell people that parabolic flight should actually be called elliptic flight or atoms should really be called toms or iron-56 is unstable. Darsie42 (talk) 09:15, 18 July 2024 (UTC)

title: Talk:Star system


text:
User talk:Jendral

Write your comments here Jendral 01:42, 11 Mar 2004 (UTC)

title: User talk:Jendral


text:
Talk:Pyrolysis

Uncategorized

 * (added in retrospect)--Tunheim 19:10, 3 February 2007 (UTC)

--Alex 08:31, 17 July 2006 (UTC)

Section on Bio-oil?
I still think that there should be a section on bio-oil: 1) There are 4 sections on solid products of pyrolysis: charcoal, biochar, coke and carbon fiber. There is only 1 section on biofule that looks at liquid products.  This is unbalanced. 2) The current section on biofuel ignores the real difficulties encountered when using bio-oil as a fuel. 3) Although some companies, recently, have used bio-oil as a biofuel, the companies that have been in business for more than 10 years produce bio-oil for non-fuel applications (Ensyn and RTI, for example). It would better to replace the "bio-fuel" title by "bio-oil" and, then, talk about fuel and other applications. Cbriens (talk) 05:55, 12 January 2009 (UTC)

Anhydrous pyrolysis
I slightly modified the first sentence of the Anhydrous Pyrolysis section to make it compatible with the rest of the article, i.e. the presence of a section on Hydrous Pyrolysis.--Cbriens 17:06, 27 October 2007 (UTC)

Waste pyrolysis
This page needs a subsection on Waste pyrolysis plants which are being globally proposed as alternative waste treatment solutions.--Alex 11:48, 25 July 2006 (UTC)
 * i've shifted things around a bit, there is a new section which includes waste as an industrial source David Woodward 08:01, 28 October 2007 (UTC)

Range of temperatures
It says: "Pyrolysis typically occurs under pressure and at operating temperatures above 430°C (800°F)." This phrase applies only to *some* process of *industrial* pyrolysis, which should be specified (perhaps pyrolysis of wood scraps and sawdust to generate charcoal+?). Pyrolysis is a general term and it can occur anywhere (nature, kitchen, lab, etc.), to any (organic?) substance, at temperatures as low as 100°C. Jorge Stolfi 01:43, 11 Mar 2004 (UTC)

 * Jorge Stolfi, could you possibly read this pictoral backgrounder I wrote, and tell me or just fix anything you find wrong with it? I am using it in an RfC, and would like someone else to check it if possible. Fifteen years later, this pyrolysis article is still rather focussed on oil chemistry; if you have time to broaden it, I'd also really appreciate that. I've added a picture of charcoal. HLHJ (talk) 01:34, 23 February 2019 (UTC)
 * HLHJ, thanks for that diagram and text! I have added the diagram to this article, and adapted your text on stages of pyrolysis to the new section "General processes and mechanisms". The rest of your text and the picture gallery seem more appropriate for other articles, such as charcoal. If you are willing to improve that diagram, may I suggest that you trim down the text labels to the bare minimum. Namely, I think that these texts would be enough:
 * Oxidation//Carbon combines with O2 yielding CO and CO2
 * Pyrolysis//Organic molecules break down, volatile products escape
 * Dehydration//Little chemical change, water and volatiles escape
 * water//freezes •   water//boils  •  carbon//ignites
 * Charring (Carbonization)//Formation of brown-black char
 * Most of the information in the current text labels should be (and already is) in the text of the article. Also, I would put the four bands in the order of increasing temperature from top to bottom: that is, Dehydration, Pyrolysis, Charring, and Oxidation -- all four above the temperature scale--Jorge Stolfi (talk) 01:19, 3 March 2019 (UTC)

Firefighting
Why is this article in the firefighting category? --Andrew 20:04, Feb 7, 2005 (UTC)

 * You’re absolutely right 212.102.225.147 11:06, 23 Jun 2005 (UTC)

 * I believe you mean "Yes, that was an error". Thanks for fixing the categories. (SEWilco 14:36, 23 Jun 2005 (UTC))

 * Yep... you’re also right. Weird, two agreeings on such a little talk page. 212.102.225.147 29 June 2005 06:51 (UTC)

 * I can see how it makes sense. A lot of the knowledge on how to best pyrolyse materials has actually been invented by the people that work with preventing it. In firefighting, or more specifically when making fire-dampening (what is the right term here) materials, you wanna avoid too much pyrolysis. So pyrolysis is a very important reaction to long-term firefighting, just like uv-induced high-altitude detoriation might be an issue for the flight industry. Even though the day to day people might not be thinking to much about it (firefighters / pilots, depending on the example). --Alf 17:05, 27 July 2006 (UTC)

 * Added Pyrolysis. Makes sense now? --Tunheim 11:48, 21 March 2007 (UTC)

some discussion recently in New Scientist about unburnt pyrolysis products: http://environment.newscientist.com/channel/earth/mg19526151.900-ignition-impossible-when-wildfires-set-the-air-alight.html http://www.newscientist.com/article/mg19526200.600-burning-bush.html David Woodward 08:08, 28 October 2007 (UTC)

Term used more loosely?
I believe this term is sometimes used more loosely to mean "heating to decompose organic materials" (absense of O2 not specified). I know that this is not really correct, but I have see this in, for example, analytic glassware cleaning protocols. Can anyone confirm this looser definition? ike9898 22:27, 6 December 2005 (UTC)

 * The strictest definition is that contained in the very term pyrolysis: decomposition or dissolution (lysis) by intense heat or by fire (pyros, both from Greek). When it comes to organics, of course, the absence of O2 is in most cases a must so that oxidation or combustion are not the main reactions.  So you are partially right.--Unconcerned 08:05, 7 December 2005 (UTC)

 * Hmm. I don't understand your meaning. If you are trying to eliminate surface contaminants, do you really care if those contaminants are oxidized or combusted? ike9898 14:43, 7 December 2005 (UTC)

 * Well, the term might be used in some cases as a fancy substitute for burning, but the chemical reaction/process of pyrolysis is fundamentally different from a combustion process in that the reactant molecules are fragmented without any incorporation of new atoms. It'd be nice though if you could include in the article the specific usage you say you're aware of.--Unconcerned 05:23, 8 December 2005 (UTC)

 * I'd say this is an example of mis-use of the word. Simple and easy :P --Tunheim 19:13, 3 February 2007 (UTC)

Merge?
There's three closely related articles on this general topic: This one, Destructive distillation and Cracking (chemistry). The cracking article is mostly concerned with petroleum, but the Pyrolysis and Destructive distillation have large overlaps. I think at least those two should be merged. Toiyabe 22:30, 22 February 2006 (UTC)

 * all the keywords are all used in a different context, different application, you can see for yourself when you look at the what links here. These articles should not merge. V8rik 00:03, 23 February 2006 (UTC)

 * The "what links here" for Pyrolysis and Destructive Distillation look pretty similar in application and context to me. Can you explain what the difference between Pyrolysis and Destructive Distillation is? Toiyabe 01:22, 23 February 2006 (UTC)

 * pyrolysis in the laboratory is actually used in organic synthesis particularly radical chemistry and rearrangements. Destructive Distillation is an industrial process. V8rik 17:56, 23 February 2006 (UTC)

 * I am no chemist, but I would guess that "Destructive distillation" (DD) is generally used for industrial processes, and implies that the distilled phases are condensed and used; whereas pyrolysis is a geeneral chemical process, that may happen in any settings (including by accident) and does not imply recovery or use of the byproducts. So DD uses pyrolysis, but there is much pyrolysis that is not DD. Makes sense? Jorge Stolfi 12:51, 23 February 2006 (UTC)

 * OK, I can live with that. To be consistent, a lot of the links to pyrolysis should be moved to DD.  DD and pyrolysis should include text that explains the distinction. Toiyabe 16:50, 23 February 2006 (UTC)

I have suggested that the stub "Dry distillation" be merged into this article because:

 * Dry distillation is essentially the same as pyrolysis.
 * This is much more of a complete article than is the stub suggested to be merged into this article.

I have tagged both this article and the stub with merge tags. - mbeychok 21:34, 7 May 2006 (UTC)

 * Dry distillation is not the same as pyrolysis. Dry distillation does not necessarily involve chemical decomposition.  Destructive distillation is pyrolysis with collection of produced gases.

These should not be merged. According to the "dry distillation" entry, there is an intent to collect the byproducts from a reaction, so it is a process. Pyrolysis refers to general chemical thermal decomposition, with or without oxygen present, and the compound doesn't even have to be organic. Sometimes industrial or lab terminology hijacks a strict definition to make it into more of a process definition. If this is the case for a specific use of the term "pyrolysis", a link should be added to point to "dry distillation". 208.223.129.170 14:38, 1 June 2006 (UTC)

 * Non-mergers win by a small but perceptible margin, merge notice removed..... V8rik 22:24, 12 August 2006 (UTC)

 * To me dry distillation and destructive distillation seems to be the same thing. It has been previously stated in the discussion thread of both articles that they are not the same thing (A B). However no explanation or references has been given to back up the statement. Would someone care to explain the difference? Please reply at destructive distillation talk page. --Alf 09:33, 22 December 2006 (UTC)

Pyrolysis with charcoal production and coke production?
I am not especially happy that the two industrial examples above are listed as examples of pyrolysis. Strictly speaking, they are not. Both involve partial combustion using air in order to generate the heat required for the pyrolysis. In both examples about 10% of the material is combusted, to pyrolyse the other 90%. I am not arguing that these processes don't contain pyrolysis, they do. But they are not examples of pyrolysis in its true sense, which must, by necessity involve indirect heating (to avoid contact with oxygen or toher reagents). What do you think?

 * I think they are important examples of pyrolysis being part of an industrial/chemical process. Just like an ion transfer or a reduction might be part of a more complex chemical process. As long as we make it clear that the pyrolysis is fueled by the heat from the combustion. So in my opinion it's a good example, but it might be possible to write it better. --Alf 09:42, 22 December 2006 (UTC)

I added other processes that do not use partial combustion--Cbriens 18:37, 2 January 2007 (UTC)

Link spam
Presently (http://en.wikipedia.org/w/index.php?title=Pyrolysis&oldid=105365069) there are multiple links in the article to companies working with pyrolysis technology. They are incorporated into the text. However, to me, it makes the article seem a little more like a buyers guide than an encyclopædic article. Any thoughts? Are there any Wikipedia policies, discussions or guidelines on this? Also, unless I receive any good reasons to keep these links, I'll probably remove them. --Tunheim 09:59, 6 February 2007 (UTC)

I agree. Remove them. No disrespect to the companies concerned, but they do not deserve special status amongst hundreds of others. The examples of particular company processes give detail but not depth or understanding to the article. Indeed, they tend to give a bias and a suggestion that this is something new.Chemical Engineer 21:49, 1 September 2007 (UTC)

 * totally agree, i've just had a big session on this page and done some work on cleanup from this point of view. Relevant policy is WP:SOAP, specifically in these cases WP:NOT#ADVERTISING. I've changed some comm. links to alternative refs, burrowed down in comm. sites to link to more useful page rather than comm. front page, removed some paras all together (e.g. mobile fluidized bed). I have left some comm links in an external links section, since there is some relevance. Hopefully this has lifted the article standard. I think this is a particularly important article because of the potential for carbon seq. David Woodward 08:17, 28 October 2007 (UTC)

more to do
i'm wikied out at the moment, having left some jobs undone, i will probably be back, but here are some to-do's for anybody
 * probably remove some detail about biochar, i don't want to lose material thought, so this might be transferred to biochar if it is not already duplicated there
 * maybe too much info still in "4. Processes for biomass pyrolysis"? David Woodward 08:22, 28 October 2007 (UTC)

 * Reference 14 doesn't exist anymore. Link does not work anymore. — Preceding unsigned comment added by Thvranken (talk • contribs) 15:48, 22 November 2012 (UTC)

Comment
This page should include a link to "Wood Gas" and to "Charcoal". The pyrolysis of wood produces a solid; the charcoal, and also gasses; the "wood gasses". These are all related concepts. I haven't figured out how to add links or I would do it myself. Alexander Selkirk Alexselkirk1704 (talk) 17:37, 12 April 2008 (UTC)

Microwaves should be mentioned as they are used for this. 80.186.110.204 (talk) 08:44, 3 July 2009 (UTC)

"bio-oil" redirect
I think this should be changed because of the product called Bio-Oil (TM) http://www.bio-oil-direct.co.uk/ Eugene-elgato (talk) 18:35, 8 February 2009 (UTC)
 * Agreed, I didn't expect to come here either 87.194.30.190 (talk) 21:47, 8 May 2009 (UTC)

 * In the research field, we call it either bio-oil of pyrolysis oil. Kind of like "Kleenex" has come to be the name of nose-tissues. If it really bothers you, go ahead and change all references to "bio-oil" to "pyrolysis-oil" (or "py-oil"). PyrolysisGenius (talk) 23:19, 25 June 2012 (UTC)

Carcinogens
Some mention of the carcinogens produced by the pyrolysis of food would be appropriate. 78.144.248.102 (talk) 10:42, 30 October 2009 (UTC)

This site mentions that heterocyclic amines and polycyclic aromatic hydrocarbons are known carcinogens produced when muscle meat is cooked at high temperatures. The site does not specify whether this is due to pyrolysis or some other process. http://www.cancer.gov/cancertopics/factsheet/Risk/cooked-meats The12thMan (talk) 21:41, 8 July 2011 (UTC)

Pyrolysis or non-organic materials
The article has been modified so as to imply that pyrolysis applies only to organic substances. However the term seems to be used also for inorganic substances, e.g. "Yakubovich and coworkers obtained insoluble polymers [...] by the pyrolysis of phosphazene phosphoxides at 220°C." . So I will restore the original wording "mainly used for organics" (but not exclusively). All the best, --Jorge Stolfi (talk) 22:55, 4 January 2010 (UTC)

Same as Thermolysis?
The article states that pyrolysis is a special case of thermolysis. However, reading both articles, I could not find or imagine an example of thermolysis that is not a pyrolyis. In fact, the IUPAC Gold Book defines them as synonyms. http://goldbook.iupac.org/P04961.html and http://goldbook.iupac.org/T06326.html. Do you agree with that? 200.164.157.164 (talk) 19:21, 14 April 2010 (UTC)
 * Yes! The pages ought to be the same. However, thermolysis has colloquially come to be more broad (temperature-wise), including gasification and torrefaction as well. I don't know why, though. PyrolysisGenius (talk) 23:21, 25 June 2012 (UTC)

Pyrolysis is usually reported as a special case of thermolysis in review papers examining biomass as pyrolysis feedstock. I agree that coal for instance can be described as operated on by pyrolysis and thermolysis (with no difference at all?). If it is just a semantics issue, it'd be worth a note in the article about which scientific "cliques" use what term. I know torrefaction is usually considered a low temperature (200 celsius or less?) form of pyrolysis. Hero of Ludi (talk) 03:36, 17 August 2012 (UTC)

Chemistry and Biofuel sections edit
I expanded (actually rewrote) the Chemistry section to add more detail and improve the sense. I agreed with the original author, but just tried to add a little more detail from a personal survey of recent research. I neglected to add additional citations (I just left the original citation in place). I will add citations.

I also added a little more detail to the Biofuel section and linked out to biomass sources by name. I didn't add citations, but they could be added. Hero of Ludi (talk) 03:40, 17 August 2012 (UTC)

Laser cutting.
I believe (but don't have refs) that laser-cutting of wood produces it's effect by pyrolysis. If that's correct, it would be a useful addition to the Examples section. SteveBaker (talk) 20:10, 16 April 2013 (UTC)

External links modified
Hello fellow Wikipedians,

I have just modified 3 one external links on Pyrolysis. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit User:Cyberpower678/FaQs for additional information. I made the following changes:
 * Added archive https://web.archive.org/web/20080919135538/http://www.nnfcc.co.uk/metadot/index.pl?id=6597;isa=DBRow;op=show;dbview_id=2457 to http://www.nnfcc.co.uk/metadot/index.pl?id=6597;isa=DBRow;op=show;dbview_id=2457
 * Added archive http://web.archive.org/web/20150326030623/http://www.epa.gov:80/osw/conserve/materials/tires/tdf.htm to http://www.epa.gov/osw/conserve/materials/tires/tdf.htm
 * Added archive http://web.archive.org/web/20080723191406/http://www.wme.com.au/categories/waste_managemt/feb6_05.php to http://www.wme.com.au/categories/waste_managemt/feb6_05.php

When you have finished reviewing my changes, please set the checked parameter below to true or failed to let others know (documentation at ).

Cheers.—cyberbot II  Talk to my owner :Online 21:48, 1 June 2016 (UTC)

Energy claim
"Using tires as fuel produce equal energy as burning oil and 25% more energy than burning coal.[23]"

This statement is meaningless. Tabby (talk) 10:39, 1 August 2016 (UTC)

Cooking
Today I removed this content. Unless one cooks like my grandmother, pyrolysis and the kitchen are not connected concepts. "Pyrolysis also plays an important role in several cooking procedures, such as baking, frying, grilling, and caramelizing.

Pyrolysis occurs whenever food is exposed to high enough temperatures in a dry environment, such as roasting, baking, toasting, or grilling. It is the chemical process responsible for the formation of the golden-brown crust in foods prepared by those methods.

In normal cooking, the main food components that undergo pyrolysis are carbohydrates (including sugars, starch, and fibre) and proteins. (See: Maillard reaction.) Pyrolysis of fats requires a much higher temperature, and, since it produces toxic and flammable products (such as acrolein), it is, in general, avoided in normal cooking. However, it may occur when one is grilling fatty meats over hot coals.

Even though cooking is normally carried out in air, the temperatures and environmental conditions are such that there is little or no combustion of the original substances or their decomposition products. In particular, the pyrolysis of proteins and carbohydrates begins at temperatures much lower than the ignition temperature of the solid residue, and the volatile subproducts are too diluted in air to ignite. (In flambé dishes, the flame is due mostly to combustion of the alcohol, while the crust is formed by pyrolysis as in baking.)

Pyrolysis of carbohydrates and proteins requires temperatures substantially higher than 100 C, so pyrolysis does not occur as long as free water is present, e.g., in boiling food — not even in a pressure cooker. When heated in the presence of water, carbohydrates and proteins suffer gradual hydrolysis rather than pyrolysis. For most foods, pyrolysis is usually confined to the outer layers of food, and begins only after those layers have dried out.

Food pyrolysis temperatures are, however, lower than the boiling point of lipids, so pyrolysis occurs when frying in vegetable oil or suet, or basting meat in its own fat.

Pyrolysis also plays an essential role in the production of barley tea, coffee, and roasted nuts such as peanuts and almonds. As these consist mostly of dry materials, the process of pyrolysis is not limited to the outermost layers but extends throughout the materials. In all these cases, pyrolysis creates or releases many of the substances that contribute to the flavor, color, and biological properties of the final product. It may also destroy some substances that are toxic, unpleasant in taste, or those that may contribute to spoilage.

Controlled pyrolysis of sugars starting at 170 C produces caramel, a beige to brown water-soluble product widely used in confectionery and (in the form of caramel coloring) as a coloring agent for soft drinks and other industrialized food products.

Solid residue from the pyrolysis of spilled and splattered food creates the brown-black encrustation often seen on cooking vessels, stove tops, and the interior surfaces of ovens."--Smokefoot (talk) 01:29, 10 January 2018 (UTC)

 * As you say, while many cooking processes never reach temperatures above 100 °C, many others -- like frying, roasting, grilling, baking etc. -- definitely go beyond the Mallard reaction and involve pyrolysis of proteins and other food components. So, what waas wrong with the removed line? Wrong section? The word "important"? --Jorge Stolfi (talk) 00:36, 3 March 2019 (UTC)

Biofuels angle
This WP:UNDUE ("hippie science") was also removed. The article is about pyrolysis, not someone's dream for how if might make the world wonderful..."[Pyrolysis of plastics produces fuels] with a higher cetane value and lower sulphur content than conventional diesel. Using pyrolysis to extract fuel from end-of-life plastic is a second-best option after recycling, is environmentally preferable to landfill, and can help reduce dependency on fossil fuels and geo-extraction."

Long essay on biochar, which is tangential to this topic. Reads like a rant. " Biochar improves the soil texture and ecology, increasing its ability to retain fertilizers and release them slowly. It naturally contains many of the micronutrients needed by plants, such as selenium. Biochar is also safer than other "natural" fertilizers such as animal manure, since it has been disinfected at high temperature. And, since it releases nutrients at a slow rate, it greatly reduces the risk of water table contamination.

Biochar is also being considered for carbon sequestration, with the aim of mitigation of global warming. The solid, carbon-containing char produced can be sequestered in the ground, where it could remain for several hundred to a few thousand years. Research continues about the processes responsible for long-term sequestration of carbon in soils. "

--Smokefoot (talk) 14:38, 10 January 2018 (UTC)

Neanderthal's adhesives
" Neanderthals used pyrolysis of birch bark to produce a pitch with which they secured flaked stones to spear shafts. Recently, researchers have developed a process to pyrolyze birch bark to produce an oil that can replace phenol in phenol formaldehyde resin (these resins are mostly used to manufacture plywood). " removed as tangential.--Smokefoot (talk) 14:48, 10 January 2018 (UTC)

Top graphic needs elaboration
I'm reasonably smart and sciencey and stuff but I have no idea what is going on in the graphic that is labeled "Simplified depiction of pyrolysis chemistry". I respectfully suggest it needs a really good descriptive caption or it should be eliminated.Kirkpete (talk) 23:32, 28 February 2019 (UTC)

A Commons file used on this page or its Wikidata item has been nominated for deletion
The following Wikimedia Commons file used on this page or its Wikidata item has been nominated for deletion: Participate in the deletion discussion at the. —Community Tech bot (talk) 06:43, 11 October 2020 (UTC)
 * JapaneseOakCharcoal KuroSumi.jpg

Wiki Education assignment: Environmental Chemistry
— Assignment last updated by 07JOS (talk) 18:19, 1 December 2022 (UTC)

title: Talk:Pyrolysis