List of interstellar and circumstellar molecules
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
The molecules listed below were detected through
Sometimes a transition can involve more than one of these types of energy level e.g.
The spectrum of a particular molecule is governed by the
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
The inventory of detected molecules is highly biased towards certain types which are easier to detect: e.g. radio astronomy is most sensitive to small linear molecules with a high
One of the richest sources for detecting interstellar molecules is
The discipline of
Molecules
The following tables list molecules that have been detected in the interstellar medium or circumstellar matter, grouped by the number of component
Most of the molecules detected so far are
Diatomic (43)
Triatomic (44)
Four atoms (30)
Molecule | Designation | Mass | Ions |
---|---|---|---|
CH3 | Methyl radical[92] | 15 | CH+3[93] |
l-C3H | Propynylidyne[94] | 37 | l-C3H+[95] |
c-C3H | Cyclopropynylidyne[96] | 37 | — |
C3N | Cyanoethynyl[97] | 50 | C3N−[98] |
C3O | Tricarbon monoxide[94] | 52 | — |
C3S | Tricarbon sulfide[63]
|
68 | — |
— | Hydronium | 19 | H3O+[99] |
C2H2 | Acetylene[100] | 26 | — |
H2CN | amidogen[101]
|
28 | H2CN+[26] |
H2NC | Aminocarbyne[102] | 28 | — |
H2CO | Formaldehyde[91] | 30 | — |
H2CS | Thioformaldehyde[103] | 46 | — |
HCCN | —[104] | 39 | — |
HCCO | Ketenyl[105] | 41 | — |
— | Protonated hydrogen cyanide
|
28 | HCNH+[77]
|
— | Protonated carbon dioxide
|
45 | HOCO+[106] |
HCNO | Fulminic acid[107] | 43 | — |
HOCN | Cyanic acid[108] | 43 | — |
CNCN | Isocyanogen[109] | 52 | — |
HOOH | Hydrogen peroxide[110] | 34 | — |
HNCO | Isocyanic acid[87] | 43 | — |
HNCN | Cyanomidyl radical[111] | 41 | — |
HNCS | Isothiocyanic acid[112] | 59 | — |
NH3 | Ammonia[113] | 17 | — |
HSCN | Thiocyanic acid[114] | 59 | — |
SiC3 | Silicon tricarbide[34] | 64 | — |
HMgNC | Hydromagnesium isocyanide[115] | 51.3 | — |
HNO2 | Nitrous acid[116] | 47 | — |
Five atoms (20)
Molecule | Designation | Mass | Ions |
---|---|---|---|
— | Ammonium ion | 18 | NH+ 4[118][119] |
CH4 | Methane[120] | 16 | — |
CH3O | Methoxy radical[121]
|
31 | — |
c-C3H2 | Cyclopropenylidene[27][122][123] | 38 | — |
l-H2C3 | Propadienylidene[123] | 38 | — |
H2CCN | Cyanomethyl[124] | 40 | — |
H2C2O | Ketene[87] | 42 | — |
H2CNH | Methylenimine[125] | 29 | — |
HNCNH | Carbodiimide[126] | 42 | — |
— | Protonated formaldehyde
|
31 | H2COH+[127] |
C4H | Butadiynyl[34] | 49 | C4H−[128] |
HC3N | Cyanoacetylene[27][77][129][130] | 51 | — |
HCC-NC | Isocyanoacetylene[131] | 51 | — |
HCOOH | Formic acid[132][129] | 46 | — |
NH2CN | Cyanamide[133][134] | 42 | — |
NH2OH | Hydroxylamine[135] | 37 | — |
— | Protonated cyanogen
|
53 | NCCNH+[136] |
HC(O)CN | Cyanoformaldehyde[137] | 55 | — |
C5 | Linear C5[138] | 60 | — |
SiC4 | Silicon-carbide cluster[53] | 92 | — |
SiH4 | Silane[139] | 32 | — |
Six atoms (16)
Molecule | Designation | Mass | Ions |
---|---|---|---|
c-H2C3O | Cyclopropenone[141] | 54 | — |
E-HNCHCN | E-Cyanomethanimine[142] | 54 | — |
C2H4 | Ethylene[143] | 28 | — |
CH3CN | Acetonitrile[87][144][145] | 40 | — |
CH3NC | Methyl isocyanide[144] | 40 | — |
CH3OH | Methanol[87][146] | 32 | — |
CH3SH | Methanethiol[147] | 48 | — |
l-H2C4 | Diacetylene[148] | 50 | — |
— | Protonated cyanoacetylene
|
52 | HC3NH+[77] |
HCONH2 | Formamide[140] | 44 | — |
HOCOOH | Carbonic acid[149] | — | |
C5H | Pentynylidyne[63] | 61 | — |
C5N | Cyanobutadiynyl radical[150] | 74 | — |
HC2CHO | Propynal[151]
|
54 | — |
HC4N | —[34] | 63 | — |
CH2CNH | Ketenimine[122]
|
40 | — |
C5S | —[152] | 92 | — |
Seven atoms (13)
Molecule | Designation | Mass | Ions |
---|---|---|---|
c-C2H4O | Ethylene oxide[154] | 44 | — |
CH3C2H | Methylacetylene[27] | 40 | — |
H3CNH2 | Methylamine[155] | 31 | — |
CH2CHCN | Acrylonitrile[87][144] | 53 | — |
HCCCHNH | Propargylimine[156] | 53 | — |
H2CHCOH | Vinyl alcohol[153] | 44 | — |
C6H | Hexatriynyl radical[63] | 73 | C6H−[123][157] |
HC4CN | Cyanodiacetylene[87][130][144] | 75 | — |
HC4NC | Isocyanodiacetylene[158] | 75 | — |
HC5O | —[159] | 77 | — |
CH3CHO | Acetaldehyde[154] | 44 | — |
CH3NCO | Methyl isocyanate[160] | 57 | — |
HOCH2CN | Glycolonitrile[161] | 57 | — |
Eight atoms (14)
Molecule | Designation | Mass |
---|---|---|
H3CC2CN | Methylcyanoacetylene[163] | 65 |
HC3H2CN | Propargyl cyanide[164] | 65 |
H2COHCHO | Glycolaldehyde[165] | 60 |
(CHOH)2 | 1,2-ethenediol[166]
|
60 |
HCOOCH3 | Methyl formate[87][129] | 60 |
CH3COOH | Acetic acid[162] | 60 |
H2C6 | Hexapentaenylidene[148] | 74 |
CH2CHCHO | Propenal[122] | 56 |
CH2CCHCN | Cyanoallene[122][163] | 65 |
CH3CHNH | Ethanimine[167] | 43 |
C2H3NH2 | Vinylamine[168]
|
43 |
C7H | Heptatrienyl radical[169] | 85 |
NH2CH2CN | Aminoacetonitrile[170] | 56 |
(NH2)2CO | Urea[171] | 60 |
Nine atoms (10)
Molecule | Designation | Mass | Ions |
---|---|---|---|
CH3C4H | Methyldiacetylene[172] | 64 | — |
CH3OCH3 | Dimethyl ether[173] | 46 | — |
CH3CH2CN | Propionitrile[87][144] | 55 | — |
CH3CONH2 | Acetamide[122][140][134] | 59 | — |
CH3CH2OH | Ethanol[174] | 46 | — |
C8H | Octatetraynyl radical[175] | 97 | C8H−[176][177] |
HC7N | Cyanohexatriyne or Cyanotriacetylene[113][178][179] | 99 | — |
CH3CHCH2 | Propylene (propene)[180] | 42 | — |
CH3CH2SH | Ethyl mercaptan[181]
|
62 | — |
CH3NHCHO | N-methylformamide[134]
|
Ten or more atoms (22)
Atoms | Molecule | Designation | Mass | Ions |
---|---|---|---|---|
10 | (CH3)2CO | Acetone[87][182] | 58 | — |
10 | (CH2OH)2 | Ethylene glycol[183][184] | 62 | — |
10 | CH3CH2CHO | Propanal[122] | 58 | — |
10 | CH3OCH2OH | Methoxymethanol[185] | 62 | — |
10 | CH3C5N | Methylcyanodiacetylene[122] | 89 | — |
10 | CH3CHCH2O | Propylene oxide[186] | 58 | — |
11 | NH2CH2CH2OH | Ethanolamine[187] | 61 | — |
11 | HC8CN | Cyanotetraacetylene[178] | 123 | — |
11 | C2H5OCHO | Ethyl formate[188] | 74 | — |
11 | CH3COOCH3 | Methyl acetate[189] | 74 | — |
11 | CH3C6H | Methyltriacetylene[122][172] | 88 | — |
12 | C6H6 | Benzene[148] | 78 | — |
12 | C3H7CN | n-Propyl cyanide[188] | 69 | — |
12 | (CH3)2CHCN | 69 | — | |
13 | CH3OCH2CH2OH | 2-methoxyethanol[192]
|
76 | — |
13 | C 6H 5CN |
Benzonitrile[193] | 104 | — |
13 | HC10CN | Cyanopentaacetylene[178] | 147 | — |
17 | C9H8 | Indene[9] | 116 | — |
19 | C10H7CN | 1-cyanonaphthalene[8]
|
153 | — |
19 | C10H7CN | 2-cyanonaphthalene[8]
|
153 | — |
27 | C11H12N2O2 | Tryptophan[194] | — | |
60 | C60 | Buckminsterfullerene (C60 fullerene)[195] |
720 | C+ 60[196][197][198] |
70 | C70 | C70 fullerene[195] | 840 | — |
Deuterated molecules (22)
These molecules all contain one or more deuterium atoms, a heavier isotope of hydrogen.
Atoms | Molecule | Designation |
---|---|---|
2 | HD | Hydrogen deuteride[199][200] |
3 | H2D+, HD+ 2 |
Trihydrogen cation[199][200] |
3 | HDO, D2O | Heavy water[201][202] |
3 | DCN | Hydrogen cyanide[203] |
3 | DCO | Formyl radical[203] |
3 | DNC | Hydrogen isocyanide[203] |
3 | N2D+ | —[203] |
3 | NHD, ND2 | Amidogen[204]
|
4 | NH2D, NHD2, ND3 | Ammonia[200][205][206] |
4 | HDCO, D2CO | Formaldehyde[200][207] |
4 | DNCO | Isocyanic acid[208] |
5 | NH3D+ | Ammonium ion[209][210] |
6 | NH 2CDO; NHDCHO |
Formamide[208] |
7 | CH2DCCH, CH3CCD |
Unconfirmed (13)
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[74]
|
4 | PH3 | Phosphine[213] |
4 | MgCCH | Magnesium monoacetylide[152] |
4 | NCCP | Cyanophosphaethyne[152] |
5 | H2NCO+ | —[214] |
6 | SiH3CN | Silyl cyanide[152] |
10 | H2NCH2COOH | Glycine[215][216] |
10 | C2H5NH2 | Ethylamine[168] |
12 | CO(CH2OH)2 | Dihydroxyacetone[217][218] |
12 | C2H5OCH3 | Ethyl methyl ether[219] |
18 | C 10H+ 8 |
Naphthalene cation[220] |
24 | C24 | Graphene[221] |
24 | C14H10 | Anthracene[222][223] |
26 | C16H10 | Pyrene[222] |
See also
- Astrochemistry
- Cosmic dust
- Diffuse interstellar band
- Lists of molecules
- Molecular astrophysics
- Molecular spectroscopy
- Molecules in stars
- Polycyclic aromatic hydrocarbon (PAH)
- Tholin
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Notes
- 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.
External links
- Woon, David E. (October 1, 2010). "Interstellar and Circumstellar Molecules". Retrieved 2010-10-04.
- "Molecules in Space". Universität zu Köln. April 2022. Retrieved 2022-05-25.
- Dworkin, Jason P. (February 1, 2007). "Interstellar Molecules". NASA's Cosmic Ice Lab. Retrieved 2010-12-23.
- Wootten, Al (November 2005). "The 129 reported interstellar and circumstellar molecules". National Radio Astronomy Observatory. Retrieved 2007-02-13.
- Lovas, F. J.; Dragoset, R. A. (February 2004). "NIST Recommended Rest Frequencies for Observed Interstellar Molecular Microwave Transitions, 2002 Revision". Journal of Physical and Chemical Reference Data. 33 (1): 177. doi:10.1063/1.1633275. Archived from the originalon 2013-02-01. Retrieved 2007-02-13.
- Williams, David A.; Cecchi-Pestellini, Cesare (8 February 2023). Astrochemistry: Chemistry in Interstellar and Circumstellar Space. Royal Society of Chemistry. ISBN 978-1-83916-939-7.