Molecules in stars

Stellar molecules are molecules that exist or form in or around stars. Such formations can take place when the temperature is low enough for molecules to form, otherwise the stellar matter is restricted to atoms (chemical elements) in the forms of gas or – at very high temperatures – plasma.

Background

Matter is made up by atoms (formed by protons and other subatomic particles). When the environment is right, atoms can join together and form molecules, which give rise to most materials studied in materials science. But certain environments, such as high temperatures, don't allow atoms to form molecules. Stars have very high temperatures, primarily in their interior, and therefore there are few molecules formed in stars. For this reason, a chemist (who studies atoms and molecules) would not have much to study in a star, so stars are better explained by physicists. However, low abundance of molecules in stars isn't equated with no molecules at all. Published scientific papers from 1990s show evidence of existence of stellar molecules.^[1]

Evidence and research

Although the Sun is a star, its photosphere has a low temperature of 6,000 kelvin and therefore molecules can form. According to Roald Hoffmann, molecules are abundant in stellar ejecta.^[1] In 1995, L. Wallace and others published an article in Science showing evidence of water on the Sun, and a 2013 paper in Astrophysical Journal Letters by S. Xu, M. Jura, D. Koster, B. Klein, and B. Zuckerman gives evidence of H₂ in white dwarf stellar atmospheres.^[1][2]

Cooler stars include absorption band spectra that are characteristic of molecules. Similar absorption bands are found in sun spots which are cooler areas on the Sun. Molecules found in the Sun include MgH, CaH, FeH, CrH, NaH, OH, VO, and TiO.

In March 2015, NASA scientists reported that, for the first time, complex DNA and RNA organic compounds of life, including uracil, cytosine and thymine, have been formed in the laboratory under outer space conditions, using starting chemicals, such as pyrimidine, found in meteorites. Pyrimidine, like polycyclic aromatic hydrocarbons (PAHs), the most carbon-rich chemical found in the Universe, may have been formed in red giants or in interstellar dust and gas clouds, according to the scientists.^[3]

References

Molecules detected in outer space Molecules Diatomic Aluminium monochloride Aluminium monofluoride Aluminium monoxide Argon hydride Carbon monophosphide Carbon monosulfide Carbon monoxide Carborundum Cyanogen radical Diatomic carbon Fluoromethylidynium Hydrogen chloride Hydrogen fluoride Hydrogen (molecular) Hydroxyl radical Iron(II) oxide Magnesium monohydride cation Methylidyne radical Nitric oxide Nitrogen (molecular) Nitrogen monohydride Nitrogen sulfide Oxygen (molecular) Phosphorus monoxide Phosphorus mononitride Potassium chloride Silicon carbide Silicon mononitride Silicon monoxide Silicon monosulfide Sodium chloride Sodium iodide Sulfur monohydride Sulfur monoxide Titanium oxide Triatomic Aluminium hydroxide Aluminium isocyanide Amino radical Carbon dioxide Carbonyl sulfide CCP radical Chloronium Diazenylium Dicarbon monoxide Disilicon carbide Ethynyl radical Formyl radical Hydrogen cyanide Hydrogen isocyanide (HCN) Hydrogen isocyanide (HNC) Hydrogen sulfide Hydroperoxyl Iron cyanide Isoformyl Magnesium cyanide Magnesium isocyanide Methylene radical N2H+ Nitrous oxide Nitroxyl Ozone Phosphaethyne Potassium cyanide Protonated molecular hydrogen Sodium cyanide Sodium hydroxide Silicon carbonitride c-Silicon dicarbide Silicon naphthalocyanine Sulfur dioxide Thioformyl Thioxoethenylidene Titanium dioxide Tricarbon Water Four atoms Acetylene Ammonia Cyanic acid Cyanoethynyl Cyclopropynylidyne Formaldehyde Fulminic acid HCCN Hydrogen peroxide Hydromagnesium isocyanide Isocyanic acid Isothiocyanic acid Ketenyl Methylene amidogen Methyl radical Propynylidyne Protonated carbon dioxide Protonated hydrogen cyanide Silicon tricarbide Thioformaldehyde Tricarbon monoxide Tricarbon sulfide Thiocyanic acid Five atoms Ammonium Ion Butadiynyl Carbodiimide Cyanamide Cyanoacetylene Cyanoformaldehyde Cyanomethyl Cyclopropenylidene Formic acid Isocyanoacetylene Ketene Methane Methoxy radical Methylenimine Propadienylidene Protonated formaldehyde Protonated formaldehyde Silane Silicon-carbide cluster Six atoms Acetonitrile Cyanobutadiynyl radical E-Cyanomethanimine Cyclopropenone Diacetylene Ethylene Formamide HC4N Ketenimine Methanethiol Methanol Methyl isocyanide Pentynylidyne Propynal Protonated cyanoacetylene Seven atoms Acetaldehyde Acrylonitrile Cyanodiacetylene Ethylene oxide Hexatriynyl radical Methylacetylene Methylamine Methyl isocyanate Vinyl alcohol Eight atoms Acetic acid Aminoacetonitrile Cyanoallene Ethanimine Glycolaldehyde Heptatrienyl radical Hexapentaenylidene Methylcyanoacetylene Methyl formate Propenal Nine atoms Acetamide Cyanohexatriyne Cyanotriacetylene Dimethyl ether Ethanol Methyldiacetylene Octatetraynyl radical Propene Propionitrile Ten atoms or more Acetone Benzene Buckminsterfullerene (C60 fullerene) ("bucky-ball") C70 fullerene Cyanodecapentayne Cyanopentaacetylene Cyanotetra-acetylene Ethylene glycol Ethyl formate Methyl acetate Methyl-cyano-diacetylene Methyltriacetylene Propanal n-Propyl cyanide Pyrimidine Deuterated molecules Ammonia Ammonium ion Formaldehyde Formyl radical Heavy water Hydrogen cyanide Hydrogen deuteride Hydrogen isocyanide Methylacetylene N2D+ Trihydrogen cation Unconfirmed Anthracene Dihydroxyacetone Ethyl methyl ether Glycine Graphene H2NCO+ Linear C5 Naphthalene cation Phosphine Pyrene Silylidine Related Abiogenesis Astrobiology Astrochemistry Atomic and molecular astrophysics Chemical formula Circumstellar envelope Cosmic dust Cosmic ray Cosmochemistry Diffuse interstellar band Extraterrestrial life Extraterrestrial liquid water Forbidden mechanism Helium hydride ion Homochirality Intergalactic dust Interplanetary medium Interstellar medium Iron–sulfur world theory Kerogen Life Molecules in stars Nexus for Exoplanet System Science Organic compound Outer space PAH world hypothesis Panspermia Polycyclic aromatic hydrocarbon (PAH) RNA world hypothesis Spectroscopy Tholin Book:Chemistry Category:Astrochemistry Category:Molecules Portal:Astrobiology Portal:Chemistry