Efficient Methanol Production on the Dark Side of a Prestellar Core
- Author(s)
- Jorma Harju, Jaime E. Pineda, Anton I. Vasyunin, Paola Caselli, Stella S. R. Offner, Alyssa A. Goodman, Mika Juvela, Olli Sipilä, Alexandre Faure, Romane Le Gal, Pierre Hily-Blant, Joao Alves, Luca Bizzocchi, Andreas Burkert, Hope Chen, Rachel K. Friesen, Rolf Güsten, Philip C. Myers, Anna Punanova, Claire Rist, Erik Rosolowsky, Stephan Schlemmer, Yancy Shirley, Silvia Spezzano, Charlotte Vastel, Laurent Wiesenfield
- Abstract
We present Atacama Large Millimeter/submillimeter Array maps of the starless molecular cloud core Ophiuchus/H-MM1 in the lines of deuterated ammonia (ortho-NH2D), methanol (CH3OH), and sulfur monoxide (SO). The dense core is seen in NH2D emission, whereas the CH3OH and SO distributions form a halo surrounding the core. Because methanol is formed on grain surfaces, its emission highlights regions where desorption from grains is particularly efficient. Methanol and sulfur monoxide are most abundant in a narrow zone that follows the eastern side of the core. This side is sheltered from the stronger external radiation field coming from the west. We show that photodissociation on the illuminated side can give rise to an asymmetric methanol distribution but that the stark contrast observed in H-MM1 is hard to explain without assuming enhanced desorption on the shaded side. The region of the brightest emission has a wavy structure that rolls up at one end. This is the signature of Kelvin-Helmholtz instability occurring in sheared flows. We suggest that in this zone, methanol and sulfur are released as a result of grain-grain collisions induced by shear vorticity.
- Organisation(s)
- Department of Astrophysics
- External organisation(s)
- Max-Planck-Institut für extraterrestrische Physik, University of Helsinki, Ural Federal University, Ventspils University of Applied Sciences, University of Texas, Austin, Harvard-Smithsonian Center for Astrophysics, University of Grenoble Alpes, Centre National de la Recherche Scientifique (CNRS), Grenoble, Ludwig-Maximilians-Universität München, University of Toronto, Max-Planck-Institut für Radioastronomie, Centre National de la Recherche Scientifique (CNRS), Strasbourg , University of Alberta, Universität zu Köln, University of Arizona, University of Toulouse, Institut de Recherche en Astrophysique et Planétologie (IRAP), Université Paris Saclay
- Journal
- The Astrophysical Journal
- Volume
- 895
- No. of pages
- 18
- ISSN
- 0004-637X
- DOI
- https://doi.org/10.3847/1538-4357/ab8f93
- Publication date
- 06-2020
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 103003 Astronomy, 103004 Astrophysics
- Keywords
- ASJC Scopus subject areas
- Astronomy and Astrophysics, Space and Planetary Science
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/80b13f19-5d33-4f34-bc3b-24b242059f1a