Complex Organic Molecules in Protostars with ALMA Spectral Surveys (COMPASS)
12 affiliations
- 1Max-Planck-Institut für Radioastronomie
- 2Max-Planck-Institut für extraterrestrische Physik
- 3Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, CNRS, CNES
- 4Physikalisch-Meteorologisches Observatorium Davos und Weltstrahlungszentrum (PMOD/WRC)
- 5Department of Chemistry, Biochemistry and Pharmaceutical Sciences (DCBP), Universität Bern
- 6Niels Bohr Institute, University of Copenhagen
- 7Department of Physics and Astronomy, Seoul National University
- 8National Radio Astronomy Observatory
- 9Institute of Astronomy, Department of Physics, National Tsinghua University
- 10Univ. Grenoble Alpes, CNRS, IPAG
- 11European Southern Observatory
- 12Star and Planet Formation Laboratory, RIKEN Pioneering Research Institute, Wako-shi
Abstract
Context . There have been no robust identifications of fully deuterated methanol, CD ₃ OD, in the interstellar medium (ISM) to date.
Aims . Our goal is to continue the search for CD ₃ OD in star-forming regions to determine the deuteration pattern of methanol and set constraints on the deuteration process.
Methods . We used a sensitive imaging spectral survey of the protostellar system IRAS4A in the NGC1333 molecular cloud performed as part of the large program carried out with the Atacama Large Millimeter/submillimeter Array (ALMA) called Complex Organic Molecules in Protostars with ALMA Spectral Surveys (COMPASS). The column densities of methanol and several of its less abundant isotopologs, including deuterated ones, were derived under the assumption of local thermodynamic equilibrium (LTE).
Results . Along with the detection of several methanol isotopologs toward the binary component IRAS4A2, we report the first interstellar detection of CD ₃ OD. The deuteration pattern of methanol in IRAS4A2 is similar to the pattern measured in other low-mass protostars, with an increase in the apparent D/H ratio from the singly to multiply deuterated isotopologs. Chemical models of prestellar and protostellar cores focused on deuteration do not reproduce this pattern quantitatively. This discrepancy is even more exacerbated by the detection of CD ₃ OD. Our LTE modeling of the spectra yields low column density ratios of methanol to its ¹³ C and ¹⁸ O isotopologs while the ¹³ C to ¹⁸ O and ¹⁸ O to ¹⁷ O ratios are consistent with the isotopic ratios expected in the local ISM. We suspect that the column density of methanol is underestimated. One possible explanation is that the emission is clumpy rather than monolithic.
Conclusions . The first detection of a fully deuterated COM highlights the power of deuterium fractionation as a diagnostic tool for investigating the formation and inheritance of organic molecules during the process of star formation.
Related
- Complex Organic Molecules in Protostars with ALMA Spectral Surveys (COMPASS). VIII. First interstellar detection of fully deuterated methyl cyanide
- Complex Organic Molecules in Protostars with ALMA Spectral Surveys (COMPASS) VII. First interstellar detection of fully deuterated methanol
- Complex Organic Molecules in Protostars with ALMA Spectral Surveys (COMPASS) VIII. First interstellar detection of fully deuterated methyl cyanide
- Complex Organic Molecules in Protostars with ALMA Spectral Surveys (COMPASS) V. Tracing cavity walls and shocked knots with nonthermally desorbed CH3OH in BHR71-IRS1
- Complex Organic Molecules in Protostars with ALMA Spectral Surveys (COMPASS) II. Approach to data reduction and products for line-rich broadband (sub)millimeter spectra
BibTeX
@article{belloche2026complex,
title = {{Complex Organic Molecules in Protostars with ALMA Spectral Surveys (COMPASS)}},
author = {A. Belloche and S. Spezzano and A. Coutens and M. N. Drozdovskaya and J. K. Jørgensen and J.-E. Lee and A. L. Plunkett and D. Harsono and S. Maret and F. Cruz-Sáenz de Miera and J.-H. Jeong and P. Nazari and Y.-L. Yang and H.-S. Yun and S. Zeng},
journal = {Astronomy \& Astrophysics},
year = {2026},
month = oct,
doi = {10.1051/0004-6361/202659642},
url = {https://www.aanda.org/10.1051/0004-6361/202659642},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Complex Organic Molecules in Protostars with ALMA Spectral Surveys (COMPASS)
AU - A. Belloche
AU - S. Spezzano
AU - A. Coutens
AU - M. N. Drozdovskaya
AU - J. K. Jørgensen
AU - J.-E. Lee
AU - A. L. Plunkett
AU - D. Harsono
AU - S. Maret
AU - F. Cruz-Sáenz de Miera
AU - J.-H. Jeong
AU - P. Nazari
AU - Y.-L. Yang
AU - H.-S. Yun
AU - S. Zeng
PY - 2026
DA - 2026/10/07
JO - Astronomy & Astrophysics
DO - 10.1051/0004-6361/202659642
UR - https://www.aanda.org/10.1051/0004-6361/202659642
AB - Context . There have been no robust identifications of fully deuterated methanol, CD ₃ OD, in the interstellar medium (ISM) to date. Aims . Our goal is to continue the search for CD ₃ OD in star-forming regions to determine the deuteration pattern of methanol and set constraints on the deuteration process. Methods . We used a sensitive imaging spectral survey of the protostellar system IRAS4A in the NGC1333 molecular cloud performed as part of the large program carried out with the Atacama Large Millimeter/submillimeter Array (ALMA) called Complex Organic Molecules in Protostars with ALMA Spectral Surveys (COMPASS). The column densities of methanol and several of its less abundant isotopologs, including deuterated ones, were derived under the assumption of local thermodynamic equilibrium (LTE). Results . Along with the detection of several methanol isotopologs toward the binary component IRAS4A2, we report the first interstellar detection of CD ₃ OD. The deuteration pattern of methanol in IRAS4A2 is similar to the pattern measured in other low-mass protostars, with an increase in the apparent D/H ratio from the singly to multiply deuterated isotopologs. Chemical models of prestellar and protostellar cores focused on deuteration do not reproduce this pattern quantitatively. This discrepancy is even more exacerbated by the detection of CD ₃ OD. Our LTE modeling of the spectra yields low column density ratios of methanol to its ¹³ C and ¹⁸ O isotopologs while the ¹³ C to ¹⁸ O and ¹⁸ O to ¹⁷ O ratios are consistent with the isotopic ratios expected in the local ISM. We suspect that the column density of methanol is underestimated. One possible explanation is that the emission is clumpy rather than monolithic. Conclusions . The first detection of a fully deuterated COM highlights the power of deuterium fractionation as a diagnostic tool for investigating the formation and inheritance of organic molecules during the process of star formation.
SN - 0004-6361
SN - 1432-0746
ER -