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Universität zu Köln
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Mathematisch-Naturwissenschaftliche Fakultät

I. Physikalisches Institut

Molecules in Space

ISM/CSS, 2-7 atoms
ISM/CSS, 8-13 atoms
extragalactic molecules


Press release on the detection of ethyl formate and n-propyl cyanide toward the massive star-forming region Sagittarius B2(N).
Pressemitteilung zur Entdeckung von Ethylformiat und n-Propylcyanid in Richtung des massiven Sternentstehungsgebiets Sagittarius B2(N).

Press release on the detection of aminoacetontrile toward the massive star-forming region Sagittarius B2(N).


Note: Deuterium isotopic species are given separately only if their method of detection is intrinsically different from that of pure hydrogen ones.

The documentations generally provide information on the detection of the respective molecules, including minor isotopic species, molecules in excited vibrational states, or different media in which the species has been detected as well as links to articles.

All molecules have been detected (also) by rotational spectroscopy in the radiofrequency to far-infrared regions unless indicated otherwise.
* indicates molecules that have been detected by their rotation-vibration spectrum,
** those detected by electronic spectroscopy only.
Transition metal molecules detected in atmospheres of stars by electronic spectroscopy are currently not included.

Note: Questionable or rebuted detections have been omitted from the table. Some noteworthy cases are given below the table. Tentative detections, which have a reasonable chance to be correct, are indicated by "?". Usually the number of observed transitions that are, at least, fairly free of overlap is small. Some detections that have been reported as secure ones are indicated by "(?)" because (partial) overlap of lines cannot be ruled at the moment or because the line list is somewhat small; obviously, there may be cases on the edge.

As the decision whether a molecule can be considered as detected frequently is a controversial one we refrain from stating an exact number of molecules as detected. As of February 2009, there are approximately 150 molecules listed as detected in the interstellar medium or circumstellar shells. Most likely there are some for which the detection should be viewed as tentative or questionable. In the course of providing background information, adjustments will be made. Two reported detections have been questioned seriously. Therefore, these are viewed currently as "probably not yet detected" – see below. Thus, we recommend phrases such as "about 150 molecules have been detected in the interstellar medium or circumstellar shells".
The number of molecules detected in extragalactic sources is 36 plus 2 tentative detections.

We welcome comments on this list !


Molecules in the Interstellar Medium or Circumstellar Shells
(as of 09/2009)

2 atoms 3 atoms 4 atoms 5 atoms 6 atoms 7 atoms
H2 C3* c-C3H C5* C5H C6H
2008
AlF C2H l-C3H C4H l-H2C4 CH2CHCN
2008
AlCl C2O C3N C4Si C2H4* CH3C2H
C2** C2S C3O l-C3H2 CH3CN HC5N
CH CH2 C3S c-C3H2 CH3NC CH3CHO
CH+ HCN C2H2* H2CCN CH3OH CH3NH2
CN HCO NH3 CH4* CH3SH c-C2H4O
CO HCO+ HCCN HC3N HC3NH+ H2CCHOH
CO+ HCS+ HCNH+ HC2NC HC2CHO C6H
CP HOC+ HNCO HCOOH NH2CHO
SiC H2O HNCS H2CNH C5N
HCl H2S HOCO+
2008
H2C2O l-HC4H* (?)
KCl HNC H2CO H2NCN l-HC4N
NH HNO H2CN HNC3 c-H2C3O
NO MgCN H2CS SiH4* H2CCNH (?)
NS MgNC H3O+ H2COH+ C5N
2008
NaCl N2H+ c-SiC3 C4H
2008
OH N2O CH3* HC(O)CN
2008
PN NaCN C3N
2008
SO OCS PH3 ?
2008
SO+ SO2 HCNO
2009
SiN c-SiC2 HOCN ?
2009
SiO CO2*
SiS NH2
CS H3+*
HF H2D+, HD2+
SH* SiCN
HD AlNC
FeO ? SiNC
O2 HCP
CF+ CCP
2008
SiH ?
PO
AlO
2009
8 atoms 9 atoms 10 atoms 11 atoms 12 atoms 13 atoms
CH3C3N CH3C4H CH3C5N HC9N C6H6* (?) HC11N
HC(O)OCH3 CH3CH2CN (CH3)2CO CH3C6H C2H5OCH3 ?
CH3COOH (CH3)2O (CH2OH)2 C2H5OCHO
2009
n-C3H7CN
2009
C7H CH3CH2OH CH3CH2CHO
H2C6 HC7N
CH2OHCHO C8H
l-HC6H* (?) CH3C(O)NH2
CH2CHCHO (?) C8H
CH2CCHCN C3H6
H2NCH2CN
2008

The year most relevant to the detection (including isotopic species or vibrationally excited states) is given for recent results – the past two to three years.
Currently, two molecules have been reported as detected whose detections have been questioned fairly convincingly in subsequent papers. Therefore, we consider these molecules as not yet detected. These molecules are aminoacetic acid, H2NCH2COOH, aka glycine, and 1,3-dihydroxypropanone, aka dihydroxyacetone.


Extragalactic Molecules (as of 01/2008)

2 atoms 3 atoms 4 atoms 5 atoms 6 atoms 7 atoms
OH H2O H2CO c-C3H2 CH3OH CH3CCH
CO HCN NH3 HC3N CH3CN
H2 HCO+ HNCO CH2NH
CH ** C2H H2CS (?) NH2CN
CS HNC HOCO+
CH+ ** N2H+ C3H
CN OCS H3O+
2008
SO HCO
SiO H2S
CO+ (?) SO2
NO HOC+
NS C2S

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