Universität zu Köln

Mathematisch-Naturwissenschaftliche Fakultät

I. Physikalisches Institut

• new CDMS site

Molecules in Space

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

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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).

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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 !

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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.

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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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