Hydrogen isotope exchanges between water and methanol in interstellar ices

Faure, A.; Faure, Mathilde; Theulé, Patrice; Quirico, E.; Schmitt, Bernard

doi:10.1051/0004-6361/201526499

Cited by 34 publications

(56 citation statements)

References 64 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For deuterated methanol the CH 3 -group has been found to be significantly enhanced compared to the OH group with the D/H ratios of 12% for CH 2 DOH (ratio of the column densities of CH 2 DOH/CH 3 OH of 37%) and 1.8% for CH 3 OD (Parise et al 2004). This led Faure et al (2015) to propose that the functional groups able to establish hydrogen bonds (-OH, -NH) are expected to equilibrate with the D/H ratio in water ice during heating events. In this scenario, the OH group of glycolaldehyde should show a significantly lower D/H ratio than the CH 2 and CHO groups, in contrast to what is observed.…”

Section: Isotopologues Of Glycolaldehydementioning

confidence: 99%

The ALMA Protostellar Interferometric Line Survey (PILS)

Jørgensen

Wiel

Coutens

et al. 2016

A&A

373

582

View full text Add to dashboard Cite

Context. The inner regions of the envelopes surrounding young protostars are characterised by a complex chemistry, with prebiotic molecules present on the scales where protoplanetary disks eventually may form. The Atacama Large Millimeter/submillimeter Array (ALMA) provides an unprecedented view of these regions zooming in on Solar System scales of nearby protostars and mapping the emission from rare species. Aims. The goal is to introduce a systematic survey, "Protostellar Interferometric Line Survey (PILS)", of the chemical complexity of one of the nearby astrochemical templates, the Class 0 protostellar binary IRAS 16293−2422, using ALMA, to understand the origin of the complex molecules formed in its vicinity. In addition to presenting the overall survey, the analysis in this paper focuses on new results for the prebiotic molecule glycolaldehyde, its isomers and rarer isotopologues and other related molecules.Methods. An unbiased spectral survey of IRAS 16293−2422 covering the full frequency range from 329 to 363 GHz (0.8 mm) has been obtained with ALMA, in addition to a few targeted observations at 3.0 and 1.3 mm. The data consist of full maps of the protostellar binary system with an angular resolution of 0.5 (60 AU diameter), a spectral resolution of 0.2 km s −1 and a sensitivity of 4-5 mJy beam −1 km s −1 -approximately two orders of magnitude better than any previous studies. Results. More than 10,000 features are detected toward one component in the protostellar binary, corresponding to an average line density of approximately one line per 3 km s −1 . Glycolaldehyde, its isomers, methyl formate and acetic acid, and its reduced alcohol, ethylene glycol, are clearly detected and their emission well-modeled with an excitation temperature of 300 K. For ethylene glycol both lowest state conformers, aGg and gGg , are detected, the latter for the first time in the ISM. The abundance of glycolaldehyde is comparable to or slightly larger than that of ethylene glycol. In comparison to the Galactic Center these two species are over-abundant relative to methanol, possibly an indication of formation of the species at low temperatures in CO-rich ices during the infall of the material toward the central protostar. Both 13 C and deuterated isotopologues of glycolaldehyde are detected, also for the first time ever in the ISM. For the deuterated species a D/H ratio of ≈5% is found with no differences between the deuteration in the different functional groups of glycolaldehyde, in contrast to previous estimates for methanol and recent suggestions of significant equilibration between water and -OH functional groups at high temperatures. Measurements of the 13 C-species lead to a 12 C: 13 C ratio of ≈30, lower than the typical ISM value. This low ratio may reflect an enhancement of 13 CO in the ice due to either ion-molecule reactions in the gas before freeze-out or differences in the temperatures where 12 CO and 13 CO ices sublimate. Conclusions. The results reinforce the importance of low temperature grain surfac...

show abstract

Section: Isotopologues Of Glycolaldehydementioning

confidence: 99%

The ALMA Protostellar Interferometric Line Survey (PILS)

Jørgensen

Wiel

Coutens

et al. 2016

A&A

373

582

View full text Add to dashboard Cite

show abstract

“…Water does not exhibit the same level of fractionation as methanol in low-mass star-forming regions, with a HDO/H 2 O lying in the range 0.01-0.07 (Liu et al 2011;Parise et al 2005Parise et al , 2006Ratajczak et al 2011;Coutens et al 2012;Faure et al 2015a). However, in Orion-KL water and methanol seem to be fractionated to a similar extent (Neill et al 2013a).…”

Section: Water and Hdomentioning

confidence: 99%

“…However, in Orion-KL water and methanol seem to be fractionated to a similar extent (Neill et al 2013a). This is likely the result of recent desorption from ice mantles (see further details on thermal H/D exchanges between water and methanol during the warm-up phase in Faure et al 2015a).…”

Section: Water and Hdomentioning

confidence: 99%

“…Low levels of fractionation are typically observed, consistent with molecular formation at higher temperatures; alternatively, warm gas-phase chemistry could alter the D/H ratio in high-mass regions during the post-evaporative phase. Interestingly enough, from chemical modelling using experimental kinetic data, Faure et al (2015a) suggested that the D/H ratio measured in Orion-KL might not be representative of the original mantles due to deuterium exchanges between water and methanol in interstellar ices during the warm up phase. The study of the abundance ratio of the deuterated isotopologues methanol (CH 3 OD/CH 2 DOH) could give access to the initial deuteration of water ices before the warm up phase sets in.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Deuterated methanol toward NGC 7538-IRS1

Ospina-Zamudio

Favre

Kounkel

et al. 2019

A&A

Self Cite

View full text Add to dashboard Cite

We investigate the deuteration of methanol towards the high-mass star forming region NGC 7538-IRS1. We have carried out a multitransition study of CH 3 OH, 13 CH 3 OH and of the deuterated flavors, CH 2 DOH and CH 3 OD, between 1.0-1.4 mm with the IRAM-30 m antenna. In total, 34 13 CH 3 OH, 13 CH 2 DOH lines and 20 CH 3 OD lines spanning a wide range of upper-state energies (E up ) were detected. From the detected transitions, we estimate that the measured D/H does not exceed 1%, with a measured CH 2 DOH/CH 3 OH and CH 3 OD/CH 3 OH of about (32±8)×10 −4 and (10±4)×10 −4 , respectively. This finding is consistent with the hypothesis of a shorttime scale formation during the pre-stellar phase. We find a relative abundance ratio CH 2 DOH/CH 3 OD of 3.2 ± 1.5. This result is consistent with a statistical deuteration. We cannot exclude H/D exchanges between water and methanol if water deuteration is of the order 0.1%, as suggested by recent Herschel observations.

show abstract

“…Indeed the D/H ratio in cold dense objects can reach of the order of 0.1 -0.2 compared to the average of 1.5×10 -5 in the galactic interstellar medium 28,29 . Recent studies have reported the degree of deuterium enrichment and fractionation in many stellar objects at different evolutionary stages [30][31][32][33][34][35][36][37][38][39][40][41] . Fontani et al 42 show that surface chemistry has an important role in determining the fractional deuteration of some molecules (e.g.…”

Section: Introductionmentioning

confidence: 99%

Molecular hydrogen production from amorphous solid water during low energy electron irradiation

Gadallah

Marchione

Koehler

et al. 2017

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

This work investigates the production of molecular hydrogen isotopologues (H 2 , HD, and D 2 ) during low energy electron irradiation of layered and isotopically labelled thin films of amorphous solid water (ASW) in ultrahigh vacuum. Experimentally, the production of these molecules with both irradiation time and incident electron energy in the range 400 to 500 eV is reported as a function of the depth of a buried D 2 O layer in an H 2 O film. H 2 is produced consistently in all measurements, reflecting the H 2 O component of the film, though it does exhibit a modest reduction in intensity at the time corresponding to product escape from the buried D 2 O layer. In contrast, HD and D 2 production exhibit peaks at times corresponding to product escape from the buried D 2 O layer in the composite film. These features broaden the deeper the HD or D 2 is formed due to diffusion. A simple random-walk model is presented that can qualitatively explain the appearance profile of these peaks as a function of the incident electron penetration.

show abstract

Hydrogen isotope exchanges between water and methanol in interstellar ices

Cited by 34 publications

References 64 publications

The ALMA Protostellar Interferometric Line Survey (PILS)

The ALMA Protostellar Interferometric Line Survey (PILS)

Deuterated methanol toward NGC 7538-IRS1

Molecular hydrogen production from amorphous solid water during low energy electron irradiation

Contact Info

Product

Resources

About