Interstellar Glycine

Kuan, Yi‐Jehng; Charnley, Steven B.; Huang, Hui‐Chun; Tseng, Wei‐Ling; Kisiel, Zbigniew

doi:10.1086/375637

Cited by 370 publications

(412 citation statements)

References 57 publications

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“…In these objects icy mantles have sublimated. For over two decades, COMs have been detected only in massive hot cores, while recently they have also been observed in three hot corinos, lowmass star-forming regions (Cazaux et al 2003;Kuan et al 2004;Bottinelli et al 2004a,b). Because hot corinos have sizes of a few tens of AU, the size of the solar nebula, it is particularly relevant to study the COMs formation and destruction mechanism because of the link to the formation of the Solar System.…”

Section: Introductionmentioning

confidence: 99%

Formation of methyl formate after cosmic ion irradiation of icy grain mantles

Modica¹,

Palumbo²

2010

A&A

102

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Context. Methyl formate (HCOOCH 3 ) is a complex organic molecule detected in hot cores and hot corinos. Gas-phase chemistry fails to reproduce its observed abundance, which usually varies between 10 −7 and 10 −9 with respect to H 2 . Aims. Laboratory experiments were performed in order to investigate a solid-state route of methyl formate formation, to obtain an estimate of the amount that can be formed, and to verify whether it can account for the observed abundances. Methods. Several solid samples (16 K) of astrophysical interest were analyzed by infrared spectroscopy in the 4400−400 cm −1 range. The infrared spectral characteristics of frozen methyl formate were studied by deriving their band strength values. The effects produced upon warm-up of the samples were analyzed comparing the spectra taken at different temperatures. In order to study the formation and destruction mechanism of methyl formate in the interstellar ices, a binary mixture of methanol (CH 3 OH) and carbon monoxide (CO) ice and a sample of pure methanol were irradiated at 16 K with 200 keV protons. Methyl formate was identified through its fundamental mode (CH 3 rocking) at about 1160 cm −1 . Results. We present the mid-infrared methyl formate ice spectrum showing both the amorphous (16 K) and the crystalline (110 K) structure. We report novel measurements of the band strength values of the six main methyl formate bands. We prove the formation and the destruction of methyl formate after irradiation of CH 3 OH and a CO:CH 3 OH mixture. Extrapolating our results to the interstellar medium conditions we found that the production timescale of methyl formate agrees well with the evolutionary time of molecular clouds. The comparison with the observational data indicates that the amount of methyl formate formed after irradiation can account for the observed abundances. Conclusions. The present results allow us to suggest that gas phase methyl formate observed in dense molecular clouds is formed in the solid state after cosmic ion irradiation of icy grain mantles containing CO and CH 3 OH and released to the gas phase after desorption of icy mantles.

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Section: Introductionmentioning

confidence: 99%

Formation of methyl formate after cosmic ion irradiation of icy grain mantles

Modica¹,

Palumbo²

2010

A&A

102

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“…We looked for HCNO in several positions in SgrB2 associated with hot or warm environments, where HOCN had previously been detected (see Brünken et al 2010), while HOCN was searched for in the cold to lukewarm dense cores observed in Marcelino et al (2009). We have also included in our search the well-studied low-mass protostar IRAS 16293-2422, where HNCO has been found to be prominent (Bisschop et al 2008), and a rich organic chemistry has been widely observed as a result of mantle grain desorption and, possibly, warm gas chemistry (see, e.g., Cazaux et al 2003;Kuan et al 2004;Garrod & Herbst 2006;Garrod et al 2008, and references therein). The observed positions are shown in Table 1.…”

Section: Introductionmentioning

confidence: 99%

The puzzling behavior of HNCO isomers in molecular clouds

Marcelino

Brünken

Cernicharo

et al. 2010

A&A

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Context. Isocyanic acid (HNCO) has been observed in different physical environments in the interstellar medium (ISM) and in external galaxies. HNCO has several metastable isomers with a ground electronic singlet state: HOCN, HCNO, and HONC. The recent detection of fulminic acid (HCNO) in prestellar and protostellar cores and cyanic acid (HOCN) in warm molecular sources (e.g. hot cores) in the Galactic center proves that these species could also be common constituents of the ISM. Aims. To shed some light on the possible formation pathways of these species, we searched for HCNO in the sources where HOCN has been previously detected and vice versa. We have also included the low-mass protostar IRAS 16293-2422, where HNCO is found to be prominent. Methods. Using the new EMIR receivers at the IRAM 30-m telescope, we performed deep searches for three rotational transitions of HOCN and four of HCNO. Results. We report the detection of HOCN in four sources -three dense cores and the lukewarm corino L1527 -where HCNO has been previously observed. HOCN is tentatively detected toward the protostellar binary IRAS 16293-2422. However, HCNO has been detected neither in this source nor in the sources of the Galactic center where HOCN has been previously reported. The derived abundance ratios HCNO/HOCN are close to unity in quiescent clouds, while they are less than 0.01-0.1 in warm clouds. We attempt to explain these results by using both gas-phase and gas-grain chemical models.

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“…However, this search also failed, in a similar way to successive searches toward Sgr B2(N-LMH) and OMC1 (Hollis et al 2003a,b). In the same year, hopes were raised by the claim of glycine detection in three high-mass star-formation regions, Sgr B2(N-LMH), Orion KL, and W51 (Kuan et al 2003). However, it was first disputed (Snyder et al 2005) and finally rejected four years later Cunningham et al 2007).…”

Section: Introductionmentioning

confidence: 99%

About the detectability of glycine in the interstellar medium

Lattelais

Pauzat

Pilmé

et al. 2011

A&A

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Context. Glycine, the simplest of aminoacids, has been found in several carbonaceous meteorites. It remains unclear, however, wether glycine is formed in the interstellar medium (ISM) and therefore available everywhere in the Universe. For this reason, radioastronomers have searched for many years unsuccessfully to detect glycine in the ISM. Aims. We provide possible guidelines to optimize the return of these searches. Since, for most of the species observed so far in the ISM, the most abundant isomer of a given generic chemical formula is the most stable one (minimum energy principle (MEP)), we assess whether neutral glycine is the best molecule to search for or whether one of its isomers/conformers or ionic, protonated, or zwitterionic derivatives would have a higher probability of being detected. Methods. The question of the relative stability of these different species is addressed by means of quantum density functional theory (DFT) simulations within the hybrid B3LYP formalism. Each fully optimized structure is verified as a stationary point by means of a vibrational analysis. A comprehensive screening of 32 isomers/conformers of the C 2 H 5 O 2 N chemical formula (neutral, negative, and positive ions together with the corresponding protonated species and the possible zwitterionic structures) is carried out. In the sensitive case of the neutral compounds, more accurate relative energies were obtained by means of high level post Hartree-Fock coupled cluster calculations with large basis sets (CCSD(T)/cc-pVQZ). Results. We find that neutral glycine is not the most stable isomer and, therefore, probably not the most abundant one, which might explain why it has escaped detection so far. We find instead that N-methyl carbamic acid and methyl carbamate are the two most stable isomers and, therefore, probably the two most abundant ones. Among the non-neutral forms, we found that glycine is the most stable isomer only if protonated or zwitterionic if present in interstellar ices. Conclusions. Assuming that MEP can be applied to optimize our search for glycine, our conclusion is that this search will remain extremely difficult with the present instruments and we propose searching instead for other examples among the most stable isomers.

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Interstellar Glycine

Cited by 370 publications

References 57 publications

Formation of methyl formate after cosmic ion irradiation of icy grain mantles

Formation of methyl formate after cosmic ion irradiation of icy grain mantles

The puzzling behavior of HNCO isomers in molecular clouds

About the detectability of glycine in the interstellar medium

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