Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)

By Arnaud Belloche, H. S. P. Müller, K. Menten, Peter Schilke, Claudia Comito. 2013

299 citations recorded by the source corpus.

The discovery of amino acids in meteorites and the detection of glycine in samples returned from a comet to Earth suggest that the interstellar chemistry is capable of producing such complex organic molecules. Our goal is to investigate the degree of chemical complexity that can be reached in the ISM. We performed an unbiased, spectral line survey toward Sgr B2(N) and (M) with the IRAM 30m telescope in the 3mm window. The spectra were analyzed with a simple radiative transfer model that assumes LTE but takes optical depth effects into account. About 3675 and 945 spectral lines with a peak signal-to-noise ratio higher than 4 are detected toward N and M, i.e. about 102 and 26 lines per GHz, respectively. This represents an increase by about a factor of 2 over previous surveys of Sgr B2. About 70% and 47% of the lines detected toward N and M are identified and assigned to 56 and 46 distinct molecules as well as to 66 and 54 less abundant isotopologues of these molecules, respectively. We also report the detection of transitions from 59 and 24 catalog entries corresponding to vibrationally or torsionally excited states of some of these molecules, respectively. Excitation temperatures and column densities were derived for each species but should be used with caution. Among the detected molecules, aminoacetonitrile, n-propyl cyanide, and ethyl formate were reported for the first time in space based on this survey, as were 5 rare isotopologues of vinyl cyanide, cyanoacetylene, and hydrogen cyanide. We also report the detection of transitions from within 12 new vib. or tors. excited states of known molecules. Although the large number of unidentified lines may still allow future identification of new molecules, we expect most of these lines to belong to vib. or tors. excited states or to rare isotopologues of known molecules for which spectroscopic predictions are currently missing. (abridged)

Subfields: Astronomy and Astrophysics, Atmospheric Science, Spectroscopy

View Paper: https://www.semanticscholar.org/paper/eb539136e1f5a2e29e6b9bf65e8b5172200c730d

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. R. Garrod
2. B. McGuire
3. K. Menten
4. Arnaud Belloche
5. T. Pillai
6. P. Caselli
7. S. Ioppolo
8. H. S. P. Müller

In Atmospheric Science

1. R. Garrod
2. S. Ioppolo
3. P. Caselli
4. K. Menten
5. Arnaud Belloche
6. H. Cuppen
7. T. Lamberts
8. C. Walsh

In Spectroscopy

1. R. Garrod
2. B. McGuire
3. K. Menten
4. Arnaud Belloche
5. H. S. P. Müller
6. P. Caselli
7. A. Vasyunin
8. H. Cuppen

Citations in the corpus

• Formation of Complex Molecules in Prestellar Cores: A Multilayer Approach (2017, background): “H, which is higher than the abundance observed towards the hot core in Sgr B2 (Belloche et al. 2013; Occhiogrosso et al. 2014).”
• Exploring Molecular Complexity with ALMA (EMoCA): Deuterated complex organic molecules in Sagittarius B2(N2) (2015, methodology): “We used the input parameters of our LTE model of the IRAM 30 m spectrum of Sgr B2(N) (Belloche et al. 2013) as a starting p int to assign the lines detected in the ALMA spectra and model the emission of the detected molecules.”
• Dense gas in the Galactic central molecular zone is warm and heated by turbulence (2015, background): “All listed frequencies are rest frequencies, but we do not include many, e.g., CH3CN 12-11, that are in the observed band but were detected only in Sgr B2, since complete surveys of the rich molecular heimat in this band have been compiled elsewhere (Nummelin et al. 1998; Belloche et al. 2013).”
• Star formation rates and efficiencies in the Galactic Centre (2017, methodology): “6) and Sgr B1, we follow the method used by Walker et al. (2015), Belloche et al. (2013) and Schmiedeke et al. (2016), and the spectral classifications of the UCH II regions as determined by Mehringer et al. (1992).”
• Grain Surface Models and Data for Astrochemistry (2017, background): “Methanol has been observed abundantly in the ISM (Belloche et al. 2013) and is considered to be a resource for the formation of more complex molecules through surface reactions and after its sublimation in the gas phase (Balucani et al. 2015).”
• Formation of ethylene glycol and other complex organic molecules in star-forming regions (2016, background): “We note that the best detection up to know of EG (in SgrB2 N, the prototypical interstellar source for the search of large COMs) relies on the detection of only ∼13 unblended lines (Belloche et al. 2013), despite the much wider spectral coverage of these observations.”
• 2018 Census of Interstellar, Circumstellar, Extragalactic, Protoplanetary Disk, and Exoplanetary Molecules (2018, background): “7 References – PRIMOS: Neill et al. (2012); IRAM: Belloche et al. (2013), NRAO 12 m: Remijan et al. (2008b), CSO: McGuire et al. (2013b).”