The ALMA-PILS survey: The sulphur connection between protostars and comets: IRAS 16293-2422 B and 67P/Churyumov-Gerasimenko
Journal article, 2018

The evolutionary past of our Solar system can be pieced together by comparing analogous lowmass protostars with remnants of our Protosolar Nebula - comets. Sulphur-bearing molecules may be unique tracers of the joint evolution of the volatile and refractory components. ALMA Band 7 data from the large unbiased Protostellar Interferometric Line Survey are used to search for S-bearing molecules in the outer disc-like structure, ~60 au from IRAS 16293-2422 B, and are compared with data on 67P/Churyumov-Gerasimenko (67P/C-G) stemming from the ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) instrument aboard Rosetta. Species such as SO 2 , SO, OCS, CS, H 2 CS, H 2 S, and CH 3 SH are detected via at least one of their isotopologues towards IRAS 16293-2422 B. The search reveals a first-time detection of OC 33 S towards this source and a tentative first-time detection of C 36 S towards a low-mass protostar. The data show that IRAS 16293-2422 B contains much more OCS than H 2 S in comparison to 67P/C-G; meanwhile, the SO/SO 2 ratio is in close agreement between the two targets. IRAS 16293-2422 B has a CH 3 SH/H 2 CS ratio in range of that of our Solar system (differences by a factor of 0.7-5.3). It is suggested that the levels of UV radiation during the initial collapse of the systems may have varied and have potentially been higher for IRAS 16293-2422 B due to its binary nature; thereby, converting more H 2 S into OCS. It remains to be conclusively tested if this also promotes the formation of S-bearing complex organics. Elevated UV levels of IRAS 16293-2422 B and a warmer birth cloud of our Solar system may jointly explain the variations between the two low-mass systems.

ISM: molecule

Comets: general

Astrochemistry

Stars: protostars

Author

M. N. Drozdovskaya

University of Bern

E. F. van Dishoeck

Max Planck Institute

Leiden University

J. K. Jorgensen

Köbenhavns Universitet

Ursina Calmonte

University of Bern

M. H. D. van der Wiel

Netherlands Institute for Radio Astronomy (ASTRON)

A. Coutens

Laboratoire d'Astrophysique de Bordeaux

H. Calcutt

Köbenhavns Universitet

H. S.P. Müller

University of Cologne

Per Bjerkeli

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics, Galactic Astrophysics

Magnus V. Persson

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics, Galactic Astrophysics

S. F. Wampfler

University of Bern

Kathrin Altwegg

University of Bern

Monthly Notices of the Royal Astronomical Society

0035-8711 (ISSN) 1365-2966 (eISSN)

Vol. 476 4 4949-4964

Subject Categories

Analytical Chemistry

Astronomy, Astrophysics and Cosmology

Other Basic Medicine

DOI

10.1093/mnras/sty462