A Rigorous Attempt to Verify Interstellar Glycine

Snyder, L. E.; Lovas, F. J.; Hollis, J. M.; Friedel, D. N.; Jewell, P. R.; Remijan, Anthony J.; Ilyushin, V. V.; Alekseev, E. A.; Dyubko, S. F.

doi:10.1086/426677

Cited by 325 publications

(301 citation statements)

References 34 publications

(177 reference statements)

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“…From the construction of a rotational temperature diagram (Snyder et al 2005, see their Appendix) based on the four emission lines presented in Fig. 2 we can derive a rotational temperature of 30.5±14.2 K and a column density of 2.2±1.2×10 15 cm −2 for PN (see Fig.…”

Section: Rotational Temperature Diagrammentioning

confidence: 99%

PO and PN in the wind of the oxygen-rich AGB star IK Tauri

Beck

Kamiński

Patel

et al. 2013

A&A

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Context. Phosphorus-bearing compounds have only been studied in the circumstellar environments of the asymptotic giant branch star IRC +10 216 and the protoplanetary nebula CRL 2688, both carbon-rich objects, and the oxygen-rich red supergiant VY CMa. The current chemical models cannot reproduce the high abundances of PO and PN derived from observations of VY CMa. No observations have been reported of phosphorus in the circumstellar envelopes of oxygen-rich asymptotic giant branch stars. Aims. We aim to set observational constraints on the phosphorous chemistry in the circumstellar envelopes of oxygen-rich asymptotic giant branch stars, by focussing on the Mira-type variable star IK Tau. Methods. Using the IRAM 30 m telescope and the Submillimeter Array, we observed four rotational transitions of PN (J = 2−1, 3−2, 6−5, 7−6) and four of PO (J = 5/2−3/2, 7/2−5/2, 13/2−11/2, 15/2−13/2). The IRAM 30 m observations were dedicated line observations, while the Submillimeter Array data come from an unbiased spectral survey in the frequency range 279−355 GHz. Results. We present the first detections of PN and PO in an oxygen-rich asymptotic giant branch star and estimate abundances X(PN/H 2 ) ≈ 3 × 10 −7 and X(PO/H 2 ) in the range 0.5−6.0 × 10 −7 . This is several orders of magnitude higher than what is found for the carbon-rich asymptotic giant branch star IRC +10 216. The diameter ( 0. 7) of the PN and PO emission distributions measured in the interferometric data corresponds to a maximum radial extent of about 40 stellar radii. The abundances and the spatial occurrence of the molecules are in very good agreement with the results reported for VY CMa. We did not detect PS or PH 3 in the survey. Conclusions. We suggest that PN and PO are the main carriers of phosphorus in the gas phase, with abundances possibly up to several 10 −7 . The current chemical models cannot account for this, underlining the strong need for updated chemical models that include phosphorous compounds.

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Section: Rotational Temperature Diagrammentioning

confidence: 99%

PO and PN in the wind of the oxygen-rich AGB star IK Tauri

Beck

Kamiński

Patel

et al. 2013

A&A

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“…Here we follow the line identification process as presented in Snyder et al (2005). While we refer the reader to the Snyder et al (2005) paper for a detailed explanation of the recipe one has to follow in order to identify a spectral line, here we very briefly summarise the criteria used: We have used the JPL, CDMS, and Lovas/NIST molecular spectroscopy databases for line identification 2 . We find that there are uncertainties in both the frequencies of lines in the molecular databases and the observed frequency of the unidentified astronomical lines.…”

Section: Molecular Contentmentioning

confidence: 99%

A high-resolution study of complex organic molecules in hot cores

Calcutt

Viti

Codella

et al. 2014

Monthly Notices of the Royal Astronomical Society

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We present the results of a line identification analysis using data from the IRAM Plateau de Bure Inferferometer, focusing on six massive star-forming hot cores: G31.41+0.31, G29.96-0.02, G19.61-0.23, G10.62-0.38, G24.78+0.08A1 and G24.78+0.08A2. We identify several transitions of vibrationally excited methyl formate (HCOOCH 3 ) for the first time in these objects as well as transitions of other complex molecules, including ethyl cyanide (C 2 H 5 CN), and isocyanic acid (HNCO). We also postulate a detection of one transition of glycolaldehyde (CH 2 (OH)CHO) in two new hot cores. We find G29.96-0.02, G19.61-0.23, G24.78+0.08A1 and G24.78+0.08A2 to be chemically very similar. G31.41+0.31, however, is chemically different: it manifests a larger chemical inventory and has significantly larger column densities. We suggest that it may represent a different evolutionary stage to the other hot cores in the sample, or it may surround a star with a higher mass. We derive column densities for methyl formate in G31.41+0.31, using the rotation diagram method, of 4×10 17 cm −2 and a T rot of ∼170 K. For G29.96-0.02, G24.78+0.08A1 and G24.78+0.08A2, glycolaldehyde, methyl formate and methyl cyanide all seem to trace the same material and peak at roughly the same position towards the dust emission peak. For G31.41+0.31, however, glycolaldehyde shows a different distribution to methyl formate and methyl cyanide and seems to trace the densest, most compact inner part of hot cores.

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“…Among them, glycine (NH 2 CH 2 COOH, the simplest amino acid) has been searched for in the interstellar medium by many groups but has not been detected, and only upper limits are given by the most sensitive studies (e.g. Combes et al 1996;Guélin et al 2008;Snyder et al 2005). On the other hand, observing abundant complex molecules is necessary for characterizing the gas temperature and density of the various Orion-KL molecular source components.…”

Section: Introductionmentioning

confidence: 99%

HCOOCH₃as a probe of temperature and structure in Orion-KL

Favre

Despois

Brouillet

et al. 2011

A&A

238

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Context. The Orion Kleinmann-Low nebula (Orion-KL) is a complex region of star formation. Whereas its proximity allows studies on a scale of a few hundred AU, spectral confusion makes it difficult to identify molecules with low abundances. Aims. We studied an important oxygenated molecule, HCOOCH 3 , to characterize the physical conditions, temperature, and density of the different molecular source components. Methyl formate presents strong close rotational transitions covering a wide range of energy, and its emission in Orion-KL is not contaminated by the emission of N-bearing molecules. This study will help in the future 1) to constrain chemical models for the formation of methyl formate in gas phase or on grain mantles and 2) to search for more complex or prebiotic molecules. Methods. We used high-resolution observations from the IRAM Plateau de Bure Interferometer to reduce spectral confusion and to better isolate the molecular emission regions. We used twelve data sets with a spatial resolution down to 1.8 × 0.8 . Continuum emission was subtracted by selecting apparently line-free channels. Results. We identify 28 methyl formate emission peaks throughout the 50 field of observations. The two strongest peaks, named MF1 and MF2, are in the Compact Ridge and in the southwest of the Hot Core, respectively. From a comparison with single-dish observations, we estimate that we miss less than 15% of the flux and that spectral confusion is still prevailing as half of the expected transitions are blended over the region. Assuming that the transitions are thermalized, we derive the temperature at the five main emission peaks. At the MF1 position in the Compact Ridge we find a temperature of 80 K in a 1.8 × 0.8 beam size and 120 K on a larger scale (3.6 × 2.2 ), suggesting an external source of heating, whereas the temperature is about 130 K at the MF2 position on both scales. Transitions of methyl formate in its first torsionally excited state are detected as well, and the good agreement of the positions on the rotational diagrams between the ground state and the v t = 1 transitions suggests a similar temperature. The LSR velocity of the gas is between 7.5 and 8.0 km s −1 depending on the positions and column density peaks vary from 1.6 × 10 16 to 1.6 × 10 17 cm −2 . A second velocity component is observed around 9−10 km s −1 in a north-south structure stretching from the Compact Ridge up to the BN object, and this component is warmer at the MF1 peak. The two other C 2 H 4 O 2 isomers are not detected, and the derived upper limit for the column density is ≤3 × 10 14 cm −2 for glycolaldehyde and ≤2 × 10 15 cm −2 for acetic acid. From the 223 GHz continuum map, we identify several dust clumps with associated gas masses in the range 0.8 to 5.8 M . Assuming that the methyl formate is spatially distributed as the dust is, we find relative abundances of methyl formate in the range ≤0.1 × 10 −8 to 5.2 × 10 −8 . We suggest a relation between the methyl formate distribution and shocks as traced by 2.12 μm H 2 emission.

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A Rigorous Attempt to Verify Interstellar Glycine

Cited by 325 publications

References 34 publications

PO and PN in the wind of the oxygen-rich AGB star IK Tauri

PO and PN in the wind of the oxygen-rich AGB star IK Tauri

A high-resolution study of complex organic molecules in hot cores

HCOOCH₃as a probe of temperature and structure in Orion-KL

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A Rigorous Attempt to Verify Interstellar Glycine

Cited by 325 publications

References 34 publications

PO and PN in the wind of the oxygen-rich AGB star IK Tauri

PO and PN in the wind of the oxygen-rich AGB star IK Tauri

A high-resolution study of complex organic molecules in hot cores

HCOOCH3as a probe of temperature and structure in Orion-KL

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Product

Resources

About

HCOOCH₃as a probe of temperature and structure in Orion-KL