List of interstellar and circumstellar molecules

File:Ssc2003-06g.jpg

Infrared spectrum of HH 46/47 (image in inset), with vibrational bands of several molecules labelled in colour

This is a list of molecules that have been detected in the interstellar medium and circumstellar envelopes, grouped by the number of component atoms. The chemical formula is listed for each detected compound, along with any ionized form that has also been observed.

Background

File:Rotational spectrum example.png

Idealised example of the rotational spectrum (bottom) produced by transitions between different rotational energy levels (top) of a simple linear molecule. <math>B</math> is the rotational constant of the molecule, <math>J</math> is the rotational quantum number, <math>J'</math> is the upper level and <math>J</math> is the lower level.

The molecules listed below were detected through astronomical spectroscopy. Their spectral features arise because molecules either absorb or emit a photon of light when they transition between two molecular energy levels. The energy (and thus the wavelength) of the photon matches the energy difference between the levels involved. Molecular electronic transitions occur when one of the molecule's electrons moves between molecular orbitals, producing a spectral line in the ultraviolet, optical or near-infrared parts of the electromagnetic spectrum. Alternatively, a vibrational transition transfers quanta of energy to (or from) vibrations of molecular bonds, producing signatures in the mid- or far-infrared. Gas-phase molecules also have quantised rotational levels, leading to transitions at microwave or radio wavelengths.<ref name=shu82/>

Sometimes a transition can involve more than one of these types of energy level e.g. ro-vibrational spectroscopy changes both the rotational and vibrational energy level. Occasionally all three occur together, as in the Phillips band of C₂ (diatomic carbon), in which an electronic transition produces a line in the near-infrared, which is then split into several vibronic bands by a simultaneous change in vibrational level, which in turn are split again into rotational branches.<ref>Template:Cite journal</ref>

The spectrum of a particular molecule is governed by the selection rules of quantum chemistry and by its molecular symmetry. Some molecules have simple spectra which are easy to identify, whilst others (even some small molecules) have extremely complex spectra with flux spread among many different lines, making them far harder to detect.<ref name=mcguire_review>Template:Cite journal</ref> Interactions between the atomic nuclei and the electrons sometimes cause further hyperfine structure of the spectral lines. If the molecule exists in multiple isotopologues (versions containing different atomic isotopes), the spectrum is further complicated by isotope shifts.

Detection of a new interstellar or circumstellar molecule requires identifying a suitable astronomical object where it is likely to be present, then observing it with a telescope equipped with a spectrograph working at the required wavelength, spectral resolution and sensitivity. The first molecule detected in the interstellar medium was the methylidyne radical (CH^•) in 1937, through its strong electronic transition at 4300 angstroms (in the optical).<ref name=woon05/> Advances in astronomical instrumentation have led to increasing numbers of new detections. From the 1950s onwards, radio astronomy began to dominate new detections, with sub-mm astronomy also becoming important from the 1990s.<ref name=mcguire_review/>

The inventory of detected molecules is highly biased towards certain types which are easier to detect. For example, radio astronomy is most sensitive to small linear molecules with a high molecular dipole.<ref name=mcguire_review/> The most common molecule in the Universe, H₂ (molecular hydrogen), is completely invisible to radio telescopes because it has no dipole;<ref name=mcguire_review/> its electronic transitions are too energetic for optical telescopes, so detection of H₂ required ultraviolet observations with a sounding rocket.<ref name=apj161/> Vibrational lines are often not specific to an individual molecule, allowing only the general class to be identified. For example, the vibrational lines of polycyclic aromatic hydrocarbons (PAHs) were identified in 1984,<ref name="leger_puget">Template:Cite journal</ref> showing the class of molecules is very common in space,<ref>Template:Cite journal</ref> but it took until 2021 to identify any specific PAHs through their rotational lines.<ref name=mcguire_pah/><ref name=burkhardt_indene/>

File:CW Leonis - HST - Heic2112a.jpg

The carbon star CW Leonis. The visible shells of circumstellar material were ejected by the central star over thousands of years.

One of the richest sources for detecting interstellar molecules is Sagittarius B2 (Sgr B2), a giant molecular cloud near the centre of the Milky Way. About half of the molecules listed below were first found in Sgr B2, and many of the others have been subsequently detected there.<ref name=ajss60/> Many of the largest molecules were first detected in another molecular cloud, TMC-1. A rich source of circumstellar molecules is CW Leonis (also known as IRC +10216), a nearby carbon star, where about 50 molecules have been identified.<ref name=kaler2002/> There is no clear boundary between interstellar and circumstellar media, so both are included in the tables below.

The discipline of astrochemistry includes understanding how these molecules form and explaining their abundances. The extremely low density of the interstellar medium is not conducive to the formation of molecules, making conventional gas-phase reactions between neutral species (atoms or molecules) inefficient. Many regions also have very low temperatures (typically 10 kelvin inside a molecular cloud), further reducing the reaction rates, or high ultraviolet radiation fields, which destroy molecules through photochemistry.<ref name=brown_pais95/> Explaining the observed abundances of interstellar molecules requires calculating the balance between formation and destruction rates using gas-phase ion chemistry (often driven by cosmic rays), surface chemistry on cosmic dust, radiative transfer including interstellar extinction, and sophisticated reaction networks.<ref name=pnas103d/> The use of molecular lines to determine the physical properties of astronomical objects is known as molecular astrophysics.

Molecules

The following tables list molecules that have been detected in the interstellar medium or circumstellar matter, grouped by the number of component atoms. Neutral molecules and their molecular ions are listed in separate columns; if there is no entry in the molecule column, only the ionized form has been detected. Designations (names of molecules) are those used in the scientific literature describing the detection; if none was given that field is left empty. Mass is listed in atomic mass units. Deuterated molecules, which contain at least one deuterium (²H) atom, have slightly different masses and are listed in a separate table. The total number of unique species, including distinct ionization states, is indicated in each section header.

Most of the molecules detected so far are organic. The only detected inorganic molecule with five or more atoms is SiH₄.<ref name="Klemperer2011"/> Molecules larger than that all have at least one carbon atom, with no N−N or O−O bonds.<ref name="Klemperer2011"/>

Diatomic (45)

File:Carbon-monoxide-3D-vdW.png

Carbon monoxide is frequently used to trace the distribution of mass in molecular clouds.<ref name=caps_ukent/>

Molecule	Designation	Mass	Ions
AlCl	Aluminium monochloride<ref name="aa183"/>	62.5	—
AlF	Aluminium monofluoride<ref name=apj433/>	46	—
AlO	Aluminium monoxide<ref name=apj694/>	43	—
—	Argonium<ref name="BarlowEtAl2013"/><ref name="NYT-20131213">Template:Cite news</ref>	37<ref group=note>On Earth, the dominant isotope of argon is 40Ar, so ArH+ would have a mass of 41 amu. However, the interstellar detection was of the 36ArH+ isotopologue, which has a mass of 37 amu.</ref>	ArH+
C2	Diatomic carbon<ref name=souza1977/><ref name=apj438l/>	24	—
—	Fluoromethylidynium	31	CF+<ref name=aaa454/>
CH	Methylidyne radical<ref name="NASA-20161012">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref><ref name="apj93"/>	13	CH+<ref name="ptotrsol324"/>
CN	Cyano radical<ref name="apj93" /><ref name="apj619f"/><ref name=aaa230/>	26	CN+,<ref name="dop03"/> CN−<ref name="AgúndezEtAl2010"/>
CO	Carbon monoxide<ref name="LAT-20140308" /><ref name="SCI-20140306" />	28	CO+<ref name=apjl419/>
CP	Carbon monophosphide<ref name=aaa230 />	43	—
CS	Carbon monosulfide<ref name="Ziurys06" />	44	—
FeO	Iron(II) oxide<ref name=aaa409/>	82	—
—	Helium hydride ion<ref name="EG-20190417">Template:Cite news</ref><ref name="NAT-20190417">Template:Cite journal</ref>	5	HeH+
H2	Molecular hydrogen<ref name=apj161/>	2	—
HCl	Hydrogen chloride<ref name=apj295/>	36.5	HCl+<ref name=deluca2012/>
HF	Hydrogen fluoride<ref name=apjl488/>	20	—
HO	Hydroxyl radical<ref name="Ziurys06" />	17	OH+<ref name="WyrowskiEtAl2009"/>
KCl	Potassium chloride<ref name="aa183" />	75.5	—
NH	Imidogen radical<ref name=apj376m/><ref name=mnras260_2/>	15	—
N2	Molecular nitrogen<ref name=spacedaily20040609/><ref name=Nat429/>	28	—
NO	Nitric oxide<ref name=apj359/>	30	NO+<ref name="dop03"/>
NS	Nitrogen sulfide<ref name="Ziurys06" />	46	—
NaCl	Sodium chloride<ref name="aa183" />	58.5	—
—	Magnesium monohydride cation	25.3	MgH+<ref name="dop03"/>Template:Page needed{{ safesubst:#invoke:Unsubst	$B= Template:Fix }}
O2	Molecular oxygen<ref name=omol/>	32	—
PN	Phosphorus mononitride<ref name=tb_pn/><ref name=apj321/>	45	—
PO	Phosphorus monoxide<ref name=apj666/>	47	—
SH	Sulfur monohydride<ref name=apj528/>	33	SH+<ref name="MentenEtAl2011"/>
SO	Sulfur monoxide<ref name="Ziurys06" />	48	SO+<ref name="ptotrsol324" />
SiC	Carborundum<ref name="aass226" />	40	—
SiN	–<ref name=turner1992/>	42	—
SiO	Silicon monoxide<ref name="Ziurys06" />	44	—
NaS	Sodium sulfide<ref name="ReyMontejo24" />	55	—
MgS	Magnesium sulfide<ref name="ReyMontejo24" />	56	—
SiS	Silicon monosulfide<ref name="Ziurys06" />	60	—
TiO	Titanium(II) oxide<ref name="KaminskiEtAl2013" />	64<ref group="note">Although titanium has several stable isotopes, only the 48Ti16O isotopologue was detected,<ref name="KaminskiEtAl2013" /> which has a molecular mass of 64 amu.</ref>	—

Triatomic (45)

Template:Redirect [[File:Trihydrogen-cation-3D-vdW.png|right|thumb|The [[Protonated molecular hydrogen|Template:Chem]] cation is one of the most abundant ions in the universe. It was first detected in 1993.<ref name=pnas103oka/><ref name=nature384/>]] Template:Sticky header

Molecule	Designation	Mass	Ions
AlNC	Aluminium isocyanide<ref name="Ziurys06" />	53	—
AlOH	Aluminium hydroxide<ref name=apj712/>	44	—
C3	Tricarbon<ref name=hinkle1988/><ref name=maier2001/>	36	—
C2H	Ethynyl radical<ref name="apj619f" />	25	—
CCN	Cyanomethylidyne<ref name="AndersonZiuris2014" />	38	—
C2O	Dicarbon monoxide<ref name=apjl380/>	40	—
C2S	Thioxoethenylidene<ref name="alac26"/>	56	—
C2P	—<ref name=apj677h/>	55	—
CO2	Carbon dioxide<ref name=mnras252/>	44	—
CaNC	Calcium(I) isocyanide<ref>Template:Cite journal</ref>	66	—
FeCN	Iron(I) cyanide<ref name=apjl733_2/>	82	—
—	Protonated molecular hydrogen	3	Template:Chem<ref name=pnas103oka/><ref name=nature384/>
H2C	Methylene radical<ref name=apj438h/>	14	—
—	Chloronium	37.5	H2Cl+<ref name="LisEtAl2010"/>
H2O	Water<ref name=es0970429/>	18	H2O+<ref name="OssenkopfEtAl"/>
HO2	Hydroperoxyl<ref name="PariseEtAl2012"/>	33	—
H2S	Hydrogen sulfide<ref name="Ziurys06" />	34	—
HCN	Hydrogen cyanide<ref name="apj619f" /><ref name=apj163/>	27	—
HNC	Hydrogen isocyanide<ref name=schilke01/><ref name=apj582/>	27	—
HCO	Formyl radical<ref name="apj303"/>	29	HCO+<ref name="ptotrsol324" /><ref name="apj303" /><ref name="apj420"/>
HCP	Phosphaethyne<ref name=apj662/>	44	—
HCS	Thioformyl<ref name=hcs_hsc/>	45	HCS+<ref name="ptotrsol324" /><ref name="apj420" />
—	Diazenylium<ref name="apj420" /><ref name="ptotrsol324" /><ref name=apj387/>	29	Template:Chem
HNO	Nitroxyl<ref name=hollis91/>	31	—
—	Isoformyl	29	HOC+<ref name="apj619f" />
HSC	Isothioformyl<ref name=hcs_hsc/>	45	—
KCN	Potassium cyanide<ref name="Ziurys06" />	65	—
MgCN	Magnesium(I) cyanide<ref name="Ziurys06" />	50	—
MgNC	Magnesium(I) isocyanide<ref name="Ziurys06" />	50	—
NH2	Amino radical<ref name=apj416/>	16	—
N2O	Nitrous oxide<ref name=apj436/>	44	—
NaCN	Sodium cyanide<ref name="Ziurys06" />	49	—
NaOH	Sodium hydroxide<ref name=apjle262/>	40	—
OCS	Carbonyl sulfide<ref name=apj245/>	60	—
O3	Ozone<ref name="PhillipsKnapp1980" />	48	—
SO2	Sulfur dioxide<ref name="aa130"/>	64	—
c-SiC2	c-Silicon dicarbide<ref name="aass226" />	52	—
SiCSi	Disilicon carbide<ref name="CernicharoEtAl2015" />	68	—
SiCN	Silicon carbonitride<ref name=aaa363/>	54	—
SiNC	<ref name=aaa426/>	54	—
CaC2	Calcium dicarbide<ref name=Gupta24/>	64	—
TiO2	Titanium dioxide<ref name="KaminskiEtAl2013"/>	79.9	—

Four atoms (31)

File:Formaldehyde-3D-vdW.png

Formaldehyde is an organic molecule that is widely distributed in the interstellar medium.<ref name=prl61/>

Molecule	Designation	Mass	Ions
CH3	Methyl radical<ref name=apj535_2/>	15	Template:Chem2<ref name="NAT-20230626">Template:Cite journal</ref>
l-C3H	Propynylidyne<ref name="mnotrs16"/>	37	l-C3H+<ref name="PetyEtAl2012"/>
c-C3H	Cyclopropynylidyne<ref name=aaa239/>	37	—
C3N	Cyanoethynyl<ref name=apj438b/>	50	C3N−<ref name=apj677t/>
C3O	Tricarbon monoxide<ref name="mnotrs16" />	52	—
C3S	Tricarbon sulfide<ref name="alac26" />	68	—
—	Hydronium	19	H3O+<ref name=apj380/>
C2H2	Acetylene<ref name="nat264"/>	26	—
H2CN	Methylene amidogen<ref name=apj427/>	28	H2CN+<ref name="ptotrsol324" />
H2NC	Aminocarbyne<ref name=Cabezas2021/>	28	—
H2CO	Formaldehyde<ref name=prl61/>	30	—
H2CS	Thioformaldehyde<ref name=aaa244a/>	46	—
HCCN	—<ref name=aaa244b/>	39	—
HCCO	Ketenyl<ref name="AgundezEtAl2015"/>	41	—
—	Protonated hydrogen cyanide	28	HCNH+<ref name="apj420" />
—	Protonated carbon dioxide	45	HOCO+<ref name=apj334m/>
HCNO	Fulminic acid<ref name=apj690/>	43	—
HOCN	Cyanic acid<ref name="BrünkenEtAl2010"/>	43	—
CNCN	Isocyanogen<ref>Template:Cite journal</ref>	52	—
HOOH	Hydrogen peroxide<ref name="BergmanEtAl2011">Template:Citation</ref>	34	—
HNCO	Isocyanic acid<ref name="aa130" />	43	—
HNCN	Cyanomidyl radical<ref name=rivilla2021 />	41	—
HNCS	Isothiocyanic acid<ref name=apj234f/>	59	—
NH3	Ammonia<ref name="aa138"/>	17	—
HSCN	Thiocyanic acid<ref name=apjl702/>	59	—
HNSO	Thionylimide<ref name=thionylimide/>	63	—
SiC3	Silicon tricarbide<ref name="Ziurys06" />	64	—
HMgNC	Hydromagnesium isocyanide<ref name="CabezasEtAl2013" />	51.3	—
HNO2	Nitrous acid<ref name=hono/>	47	—

Five atoms (21)

File:Methane-3D-space-filling.svg

Methane, the primary component of natural gas, has also been detected on comets and in the atmosphere of several planets in the Solar System.<ref name=mnras347/>

Molecule	Designation	Mass	Ions
—	Ammonium ion	18	Template:Chem<ref>{{#invoke:citation/CS1|citation	CitationClass=web }}</ref><ref>Template:Cite journal</ref>
CH4	Methane<ref name=apj376l/>	16	—
CH3O	Methoxy radical<ref name="CernicharoEtAl2012"/>	31	—
c-C3H2	Cyclopropenylidene<ref name="apj619f" /><ref name="precursors"/><ref name="apj552f"/>	38	—
l-H2C3	Propadienylidene<ref name="apj552f" />	38	—
H2CCN	Cyanomethyl<ref name=apj334i/>	40	—
H2C2O	Ketene<ref name="aa130" />	42	—
H2CNH	Methylenimine<ref name=apj479/>	29	—
HNCNH	Carbodiimide<ref name="McGuireEtAl2012"/>	42	—
—	Protonated formaldehyde	31	H2COH+<ref name=apj471/>
C4H	Butadiynyl<ref name="Ziurys06" />	49	C4H−<ref name=aaa61/>
HC3N	Cyanoacetylene<ref name="apj619f" /><ref name="apj420" /><ref name="apj552l" /><ref name="aaa81"/>	51	—
HCC-NC	Isocyanoacetylene<ref name=apj386/>	51	—
HCOOH	Formic acid<ref name=1971ApJ...163L..41Z/><ref name="apj552l"/>	46	—
NH2CN	Cyanamide<ref name=apj201/><ref name=Ligterink2020/>	42	—
NH2OH	Hydroxylamine<ref name=hydroxylamine/>	37	—
—	Protonated cyanogen	53	NCCNH+<ref name=aanda579/>
HC(O)CN	Cyanoformaldehyde<ref name=apj675/>	55	—
C5	Linear C5<ref name=bernath89/>	60	—
HCS2H	dithioformic acid<ref name=manna25/>	78	—
SiC4	Silicon-carbide cluster<ref name="aass226" />	92	—
SiH4	Silane<ref name=apj279/>	32	—

Six atoms (16)

File:Formamide-3D-vdW.png

In the ISM, formamide (above) can combine with methylene to form acetamide.<ref name="apj643hl"/>

Molecule	Designation	Mass	Ions
c-H2C3O	Cyclopropenone<ref name=apj643hr/>	54	—
E-HNCHCN	E-Cyanomethanimine<ref name="ZaleskiEtAl2013"/>	54	—
C2H4	Ethylene<ref name="apj244" />	28	—
CH3CN	Acetonitrile<ref name="aa130" /><ref name="apj632"/><ref name="Alma 2015">Template:Cite news</ref>	40	—
CH3NC	Methyl isocyanide<ref name="apj632" />	40	—
CH3OH	Methanol<ref name="aa130" /><ref>First Detection of Methyl Alcohol in a Planet-forming Disc. 15 June 2016.</ref>	32	—
CH3SH	Methanethiol<ref name=apj234l/>	48	—
l-H2C4	Diacetylene<ref name="Cernicharo_546"/>	50	—
—	Protonated cyanoacetylene	52	HC3NH+<ref name="apj420" />
HCONH2	Formamide<ref name="apj643hl" />	44	—
HOCOOH	Carbonic acid<ref>Template:Cite journal</ref>		—
C5H	Pentynylidyne<ref name="alac26" />	61	—
C5N	Cyanobutadiynyl radical<ref name="GuelinEtAl98"/>	74	—
HC2CHO	Propynal<ref name=apj335/>	54	—
HC4N	—<ref name="Ziurys06" />	63	—
CH2CNH	Ketenimine<ref name="precursors" />	40	—
C5S	—<ref name="Agundez+2014" />	92	—

Seven atoms (16)

File:Acetaldehyde-3D-vdW.png

Acetaldehyde (above) and its isomers vinyl alcohol and ethylene oxide have all been detected in interstellar space.<ref name="rnao011001"/>

Molecule	Designation	Mass	Ions
c-C2H4O	Ethylene oxide<ref name="boaas29"/>	44	—
CH3C2H	Methylacetylene<ref name="apj619f" />	40	—
H3CNH2	Methylamine<ref name=apj198/>	31	—
CH2CHCN	Acrylonitrile<ref name="aa130" /><ref name="apj632" />	53	—
HCCCHNH	Propargylimine<ref>Template:Cite journal</ref>	53	—
H2CHCOH	Vinyl alcohol<ref name="rnao011001" />	44	—
C6H	Hexatriynyl radical<ref name="alac26" />	73	C6H−<ref name="apj552f" /><ref name=apj652/>
HC4CN	Cyanodiacetylene<ref name="aa130" /><ref name="aaa81" /><ref name="apj632" />	75	—
HC4NC	Isocyanodiacetylene<ref name=hc4nc/>	75	—
HC5O	—<ref name=hc5o/>	77	—
CH3CHO	Acetaldehyde<ref name="boaas29" />	44	—
CH3CHS	Thioacetaldehyde<ref name="thioacetaldehyde" />	60	—
CH3NCO	Methyl isocyanate<ref name="apj812" />	57	—
HOCH2CN	Glycolonitrile<ref name=glyconitrile/>	57	—
HC3HCN	1-cyano propargyl radical<ref name=1cyanopropargyl/>	64	—
CH2C3N	3-cyano propargyl radical<ref name=3cyanopropargyl/>	64	—

Eight atoms (14)

File:Acetic-acid-3D-vdW.png

The radio signature of acetic acid, a compound found in vinegar, was confirmed in 1997.<ref name="acetic_acid"/>

Molecule	Designation	Mass
H3CC2CN	Methylcyanoacetylene<ref name="aj637" />	65
HC3H2CN	Propargyl cyanide<ref name=propargyl_cyanide/>	65
H2COHCHO	Glycolaldehyde<ref name=hollis2000/>	60
(CHOH)2	1,2-ethenediol<ref name="ethenediol"/>	60
HCOOCH3	Methyl formate<ref name="aa130" /><ref name="apj552l" />	60
CH3COOH	Acetic acid<ref name="acetic_acid" />	60
H2C6	Hexapentaenylidene<ref name="Cernicharo_546" />	74
CH2CHCHO	Propenal<ref name="precursors" />	56
CH2CCHCN	Cyanoallene<ref name="precursors" /><ref name="aj637"/>	65
CH3CHNH	Ethanimine<ref name="LoomisEtAl13" />	43
C2H3NH2	Vinylamine<ref name=Zeng2021/>	43
C7H	Heptatrienyl radical<ref name=aaa317/>	85
NH2CH2CN	Aminoacetonitrile<ref name=aaa482/>	56
(NH2)2CO	Urea<ref name="RemijanEtAl2014"/>	60

Nine atoms (11)

Molecule	Designation	Mass	Ions
CH3C4H	Methyldiacetylene<ref name="aj643"/>	64	—
CH3OCH3	Dimethyl ether<ref name=apj191/>	46	—
CH3CH2CN	Propionitrile<ref name="aa130" /><ref name="apj632" />	55	—
CH3CONH2	Acetamide<ref name="precursors" /><ref name="apj643hl" /><ref name=Ligterink2020/>	59	—
CH3CH2OH	Ethanol<ref name=apj196/>	46	—
C8H	Octatetraynyl radical<ref name=aaa309/>	97	C8H−<ref name=apj664b/><ref name=apj664r/>
HC7N	Cyanohexatriyne or Cyanotriacetylene<ref name="aa138" /><ref name="bell_483"/><ref name=apj219/>	99	—
CH3CHCH2	Propylene (propene)<ref name=apj665/>	42	—
CH3CH2SH	Ethyl mercaptan<ref name="KolesnikovaEtAl2014"/>	62	—
CH3SCH3	Dimethyl sulfide<ref name=DMS/>	62	—
CH3NHCHO	N-methylformamide<ref name=Ligterink2020/>	59	—

Ten or more atoms (24)

Atoms	Molecule	Designation	Mass	Ions
10	(CH3)2CO	Acetone<ref name="aa130" /><ref name=apj578/>	58	—
10	(CH2OH)2	Ethylene glycol<ref name="HollisEtAl2002"/><ref name="Hollis"/>	62	—
10	CH3CH2CHO	Propanal<ref name="precursors" />	58	—
10	CH3OCH2OH	Methoxymethanol<ref name=methoxymethanol/>	62	—
10	CH3C5N	Methylcyanodiacetylene<ref name="precursors" />	89	—
10	CH3CHCH2O	Propylene oxide<ref name=science352/>	58	—
11	NH2CH2CH2OH	Ethanolamine<ref>Template:Cite journal</ref>	61	—
11	HC8CN	Cyanotetraacetylene<ref name="bell_483" />	123	—
11	C2H5OCHO	Ethyl formate<ref name="arxiv4694"/>	74	—
11	CH3COOCH3	Methyl acetate<ref name="TerceroEtAl2013"/>	74	—
11	CH3C6H	Methyltriacetylene<ref name="precursors" /><ref name="aj643" />	88	—
12	C6H6	Benzene<ref name="Cernicharo_546" />	78	—
12	C3H7CN	n-Propyl cyanide<ref name="arxiv4694" />	69	—
12	(CH3)2CHCN	iso-Propyl cyanide<ref>Template:Cite news</ref><ref>Template:Cite journal</ref>	69	—
13	CH3OCH2CH2OH	2-methoxyethanol<ref name="fried2024" />	76	—
13	Template:Chem	Benzonitrile<ref name=benzonitrile/>	104	—
13	HC10CN	Cyanopentaacetylene<ref name="bell_483" />	147	—
17	C9H8	Indene<ref name=burkhardt_indene />	116	—
19	C10H7CN	1-cyanonaphthalene<ref name=mcguire_pah />	153	—
19	C10H7CN	2-cyanonaphthalene<ref name=mcguire_pah />	153	—
21	C12H7CN	1-cyanoacenaphtylene<ref name=cyanoacenaphtylene />	177	—
21	C12H7CN	5-cyanoacenaphtylene<ref name=cyanoacenaphtylene />	177	—
27	C16H9CN	1-cyanopyrene<ref name=1cyanopyrene />	227	—
27	C16H9CN	2-cyanopyrene<ref name=24cyanopyrene />	227	—
27	C16H9CN	4-cyanopyrene<ref name=24cyanopyrene />	227	—
37	C24H11CN	cyanocoronene<ref name=cyanocoronene />	325	—
60	C60	Buckminsterfullerene (C60 fullerene)<ref name=science20100722/>	720	Template:Chem<ref name=Foing1994/><ref name=cam15/><ref name=Berne2012/>
70	C70	C70 fullerene<ref name=science20100722/>	840	—

Deuterated molecules (22)

These molecules all contain one or more deuterium atoms, a heavier isotope of hydrogen. Template:Sticky header

Atoms	Molecule	Designation
2	HD	Hydrogen deuteride<ref name=aaa430/><ref name="pass50"/>
3	H2D+, Template:Chem	Trihydrogen cation<ref name=aaa430/><ref name="pass50"/>
3	HDO, D2O	Heavy water<ref name=ajss70/><ref name=apj659/>
3	DCN	Hydrogen cyanide<ref name="apj225"/>
3	DCO	Formyl radical<ref name="apj225" />
3	DNC	Hydrogen isocyanide<ref name="apj225" />
3	N2D+	—<ref name="apj225" />
3	NHD, ND2	Amidogen<ref name=melosso2020 />
4	NH2D, NHD2, ND3	Ammonia<ref name="pass50" /><ref name=apj571/><ref name=aaa403/>
4	HDCO, D2CO	Formaldehyde<ref name="pass50" /><ref name=apj362/>
4	DNCO	Isocyanic acid<ref name="formamide">Template:Cite journal</ref>
5	NH3D+	Ammonium ion<ref name="CernicharoEtAl2013" /><ref name="DomenechEtAl2013"/>
6	Template:Chem; NHDCHO	Formamide<ref name="formamide"/>
7	CH2DCCH, CH3CCD	Methylacetylene<ref name=aaa253/><ref name=apj627/>

Unconfirmed (16)

Evidence for the existence of the following molecules has been reported in the scientific literature, but the detections either are described as tentative by the authors, or have been challenged by other researchers. They await independent confirmation.

Atoms	Molecule	Designation
2	SiH	Silylidine<ref name=schilke01/>
2	CaO	Calcium oxide<ref name=ReyMontejo24/>
4	PH3	Phosphine<ref name="AgúndezEtAl2008"/>
4	MgCCH	Magnesium monoacetylide<ref name="Agundez+2014" />
4	NCCP	Cyanophosphaethyne<ref name="Agundez+2014" />
5	H2NCO+	—<ref name="GuptaEtAl2013"/>
6	SiH3CN	Silyl cyanide<ref name="Agundez+2014"/>
10	H2NCH2COOH	Glycine<ref name=apj619s/><ref name=apj593/>
10	C2H5NH2	Ethylamine<ref name=Zeng2021/>
12	CO(CH2OH)2	Dihydroxyacetone<ref name=apjl624/><ref name=apponi2006/>
12	C2H5OCH3	Ethyl methyl ether<ref name="FuchsEtAl2005"/>
18	Template:Chem	Naphthalene cation<ref name=apjl685/>
24	C24	Graphene<ref name="García-HernándezEtAl2011"/>
24	C14H10	Anthracene<ref name="Battersby">Template:Cite news</ref><ref name=arxiv1005.4388/>
26	C16H10	Pyrene<ref name="Battersby" />
27	C11H12N2O2	Tryptophan<ref name=IglesiasGroth2023/><ref name=Hudson2023/><ref name=Dhariwal2024/>

See also

• Astrochemistry
• Cosmic dust
• Diffuse interstellar band
• Lists of molecules
• Molecular astrophysics
• Molecular spectroscopy
• Molecules in stars
• Polycyclic aromatic hydrocarbon (PAH)
• Tholin

References

<references>

<ref name=glyconitrile>Template:Cite journal</ref>

<ref name=shu82>Template:Cite book</ref>

<ref name=dop03>Template:Citation</ref>

<ref name=woon05>Template:Citation</ref>

<ref name=pnas103d>Template:Citation</ref>

<ref name=brown_pais95>Template:Citation</ref>

<ref name=ajss60>Template:Citation</ref>

<ref name=caps_ukent>Template:Citation</ref>

<ref name=cam15>Template:Citation</ref>

<ref name="Ziurys06">Template:Citation</ref>

<ref name="Berne2012">Template:Citation</ref>

<ref name="aa183">Template:Citation</ref>

<ref name=schilke01>Template:Citation</ref>

<ref name=apj433>Template:Citation</ref>

<ref name=apj694>Template:Citation</ref>

<ref name=apj438l>Template:Citation</ref>

<ref name=bernath89>Template:Cite journal</ref>

<ref name=aaa454>Template:Citation</ref>

<ref name="apj93">Template:Citation</ref>

<ref name="ptotrsol324">Template:Citation</ref>

<ref name="apj619f">Template:Citation</ref>

<ref name=aaa230>Template:Citation</ref>

<ref name=apjl419>Template:Citation</ref>

<ref name=aaa409>Template:Citation</ref>

<ref name=apj161>Template:Citation</ref>

<ref name=apj295>Template:Citation</ref>

<ref name=apjl488>Template:Citation</ref>

<ref name=apj376m>Template:Citation</ref>

<ref name=Nat429>Template:Citation</ref>

<ref name=apj359>Template:Citation</ref>

<ref name=omol>Template:CitationTemplate:Bsn</ref>

<ref name=tb_pn>Template:Cite journal</ref>

<ref name=apj321>Template:Citation</ref>

<ref name=apj666>Template:Citation</ref>

<ref name=apj528>Template:Citation</ref>

<ref name="aass226">Template:Citation</ref>

<ref name=pnas103oka>Template:Citation</ref>

<ref name=apj712>Template:Citation</ref>

<ref name=apjl380>Template:Citation</ref>

<ref name="alac26">Template:Citation</ref>

<ref name=apj677h>Template:Citation</ref>

<ref name=mnras252>Template:Citation</ref>

<ref name=apj438h>Template:Citation</ref>

<ref name=es0970429>Template:Cite press releaseTemplate:Bsn</ref>

<ref name=apj163>Template:Citation</ref>

<ref name="apj303">Template:Citation</ref>

<ref name="apj420">Template:Citation</ref>

<ref name=apj662>Template:Citation</ref>

<ref name=apj582>Template:Citation</ref>

<ref name=hollis91>Template:Citation</ref>

<ref name=apj416>Template:Citation</ref>

<ref name=apj387>Template:Citation</ref>

<ref name=apj436>Template:Citation</ref>

<ref name=apj245>Template:Citation</ref>

<ref name="PhillipsKnapp1980">Template:Citation</ref>

<ref name="aa130">Template:Citation</ref>

<ref name=aaa363>Template:Citation</ref>

<ref name=aaa426>Template:Citation</ref>

<ref name=prl61>Template:Citation</ref>

<ref name="mnotrs16">Template:Citation</ref>

<ref name=aaa239>Template:Citation</ref>

<ref name=apj438b>Template:Citation</ref>

<ref name=apj677t>Template:Citation</ref>

<ref name=apj380>Template:Citation</ref>

<ref name=nat264>Template:Citation</ref>

<ref name=apj427>Template:Citation</ref>

<ref name=aaa244a>Template:Citation</ref>

<ref name=aaa244b>Template:Citation</ref>

<ref name=apj334m>Template:Citation</ref>

<ref name=apj690>Template:Citation</ref>

<ref name=apj234f>Template:Citation</ref>

<ref name="aa138">Template:Citation</ref>

<ref name=apjl702>Template:Citation</ref>

<ref name=mnras347>Template:Citation</ref>

<ref name=apj376l>Template:Citation</ref>

<ref name="precursors">Template:Cite press releaseTemplate:Bsn</ref>

<ref name="apj552f">Template:Citation</ref>

<ref name=apj334i>Template:Citation</ref>

<ref name=apj479>Template:Citation</ref>

<ref name=apj471>Template:Citation</ref>

<ref name=aaa61>Template:Citation</ref>

<ref name="aaa81">Template:Citation</ref>

<ref name=apj386>Template:Citation</ref>

<ref name="apj552l">Template:Citation</ref>

<ref name=apj201>Template:Citation</ref>

<ref name=apj675>Template:Citation</ref>

<ref name=apj279>Template:Citation</ref>

<ref name="apj643hl">Template:Citation</ref>

<ref name=apj643hr>Template:Citation</ref>

<ref name="apj632">Template:Citation</ref>

<ref name=apj234l>Template:Citation</ref>

<ref name="Cernicharo_546">Template:Citation</ref>

<ref name=apj335>Template:Citation</ref>

<ref name="rnao011001">Template:Cite press releaseTemplate:Bsn</ref>

<ref name="boaas29">Template:Citation</ref>

<ref name=apj198>Template:Citation</ref>

<ref name=apj652>Template:Citation</ref>

<ref name="acetic_acid">Template:Citation</ref>

<ref name=hollis2000>Template:Cite journal</ref>

<ref name="aj637">Template:Citation</ref>

<ref name=aaa317>Template:Citation</ref>

<ref name=aaa482>Template:Citation</ref>

<ref name="aj643">Template:Citation</ref>

<ref name=apj191>Template:Citation</ref>

<ref name=apj196>Template:Citation</ref>

<ref name=aaa309>Template:Citation</ref>

<ref name=apj664b>Template:Citation</ref>

<ref name=apj664r>Template:Citation</ref>

<ref name="bell_483">Template:Citation</ref>

<ref name=apj219>Template:Citation</ref>

<ref name=apj665>Template:Citation</ref>

<ref name=apj578>Template:Citation</ref>

<ref name="arxiv4694">Template:Citation</ref>

<ref name=aaa430>Template:Citation</ref>

<ref name="pass50">Template:Citation</ref>

<ref name=ajss70>Template:Citation</ref>

<ref name=apj659>Template:Citation</ref>

<ref name="apj225">Template:Citation</ref>

<ref name=apj571>Template:Citation</ref>

<ref name=aaa403>Template:Citation</ref>

<ref name=apj362>Template:Citation</ref>

<ref name=aaa253>Template:Citation</ref>

<ref name=apj627>Template:Citation</ref>

<ref name=apj593>Template:Citation</ref>

<ref name=apj619s>Template:Citation</ref>

<ref name=apjl624>Template:Citation</ref>

<ref name=apjl685>Template:Citation - This spectral assignment has not been independently confirmed, and is described by the authors as "tentative" (page L58).</ref>

<ref name=apjle262>Template:Citation</ref>

<ref name=apj535_2>Template:Citation</ref>

<ref name=mnras260_2>Template:Citation</ref>

<ref name=arxiv1005.4388>Template:Citation</ref>

<ref name=spacedaily20040609>Template:Cite newsTemplate:Bsn</ref>

<ref name="WyrowskiEtAl2009">Template:Citation</ref>

<ref name="OssenkopfEtAl">Template:Citation</ref>

<ref name="GuelinEtAl98">Template:Citation</ref>

<ref name="HollisEtAl2002">Template:Citation</ref>

<ref name="Hollis">Template:Cite conferenceTemplate:Bsn</ref>

<ref name="FuchsEtAl2005">Template:Citation</ref>

<ref name="AgúndezEtAl2008">Template:Citation</ref>

<ref name=science20100722>Template:Citation</ref>

<ref name="AgúndezEtAl2010">Template:Citation</ref>

<ref name="BrünkenEtAl2010">Template:Citation</ref>

<ref name=Foing1994>Template:Citation</ref>

<ref name="LisEtAl2010">Template:Citation</ref>

<ref name="MentenEtAl2011">Template:Citation</ref>

<ref name=kaler2002>Template:Cite bookTemplate:Bsn</ref>

<ref name="García-HernándezEtAl2011">Template:Citation</ref>

<ref name=apjl733_2>Template:Citation</ref>

<ref name=deluca2012>Template:Citation</ref>

<ref name=nature384>Template:Citation</ref>

<ref name="PariseEtAl2012">Template:Citation</ref>

<ref name="McGuireEtAl2012">Template:Citation</ref>

<ref name="CernicharoEtAl2012">Template:Citation</ref>

<ref name="PetyEtAl2012">Template:Citation</ref>

<ref name="LoomisEtAl13">Template:Citation</ref>

<ref name="ZaleskiEtAl2013">Template:Citation</ref>

<ref name="apj244">Template:Citation</ref>

<ref name="KaminskiEtAl2013">Template:Citation</ref>

<ref name="TerceroEtAl2013">Template:Citation</ref>

<ref name="Klemperer2011">Template:Citation</ref>

<ref name="CernicharoEtAl2013">Template:Citation</ref>

<ref name="DomenechEtAl2013">Template:Citation</ref>

<ref name="CabezasEtAl2013">Template:Citation</ref>

<ref name="BarlowEtAl2013">Template:Citation</ref>

<ref name="GuptaEtAl2013">Template:Citation</ref>

<ref name="LAT-20140308">Template:Cite news</ref>

<ref name="SCI-20140306">Template:Cite journal</ref>

<ref name="RemijanEtAl2014">Template:Citation</ref>

<ref name="KolesnikovaEtAl2014">Template:Citation</ref>

<ref name="Agundez+2014">Template:Citation</ref>

<ref name="AgundezEtAl2015">Template:Citation</ref>

<ref name="AndersonZiuris2014">Template:Citation</ref>

<ref name=CernicharoEtAl2015>Template:Citation</ref>

<ref name=aanda579>Template:Citation</ref>

<ref name="apj812">Template:Citation</ref>

<ref name="1971ApJ...163L..41Z">Template:Cite journal</ref>

<ref name=science352>Template:Cite journal</ref>

<ref name=benzonitrile>Template:Cite journal</ref>

<ref name=methoxymethanol>Template:Cite journal</ref>

<ref name=hc5o>Template:Cite journal</ref>

<ref name=hcs_hsc>Template:Cite journal</ref>

<ref name=souza1977>Template:Cite journal</ref>

<ref name=hinkle1988>Template:Cite journal</ref>

<ref name=maier2001>Template:Cite journal</ref>

<ref name=hono>Template:Cite journal</ref>

<ref name=hc4nc>Template:Cite journal</ref>

<ref name=propargyl_cyanide>Template:Cite journal</ref>

<ref name=hydroxylamine>Template:Cite journal</ref>

<ref name=apponi2006>Template:Cite journal</ref>

<ref name=Ligterink2020>Template:Cite journal</ref>

<ref name=melosso2020>Template:Cite journal</ref>

<ref name=turner1992>Template:Cite journal</ref>

<ref name=rivilla2021>Template:Cite journal</ref>

<ref name="mcguire_pah">Template:Cite journal</ref>

<ref name="burkhardt_indene">Template:Cite journal</ref>

<ref name="Zeng2021">Template:Cite journal</ref> <ref name=cyanoacenaphtylene>Template:Cite journal</ref> <ref name="Cabezas2021">Template:Cite journal</ref>

<ref name="ethenediol">Template:Cite journal</ref>

<ref name="fried2024">Template:Cite journal</ref>

<ref name=Dhariwal2024>Template:Cite journal</ref>

<ref name=IglesiasGroth2023>Template:Cite journal</ref>

<ref name=Hudson2023>Template:Cite journal</ref>

<ref name=cyanocoronene>Template:Cite journal</ref>

<ref name="1cyanopyrene">Template:Cite journal</ref>

<ref name="24cyanopyrene">Template:Cite journal</ref>

<ref name="thioacetaldehyde">Template:Cite journal</ref>

<ref name="manna25">Template:Cite journal</ref>

<ref name="thionylimide">Template:Cite journal</ref>

<ref name="DMS">Template:Cite journal</ref>

<ref name="1cyanopropargyl">Template:Cite journal</ref>

<ref name="3cyanopropargyl">Template:Cite journal</ref>

<ref name="ReyMontejo24">Template:Cite journal</ref>

<ref name="Gupta24">Template:Cite journal</ref>

</references>

External links

• {{#invoke:citation/CS1|citation

|CitationClass=web }}

• {{#invoke:citation/CS1|citation

|CitationClass=web }}

• {{#invoke:citation/CS1|citation

|CitationClass=web }}

• {{#invoke:citation/CS1|citation

|CitationClass=web }}

• Template:Cite journal
• Template:Cite book