A candidate circumbinary Keplerian disk in G35.20–0.74 N: A study with ALMA

¹ INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
e-mail: asanchez@arcetri.astro.it
² Centro de Astrofísica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal
³ ESO, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany
⁴ SOFIA Science Center, NASA Ames Research Center, Mailstop 232-12, Moffett Field, CA 94035, USA
⁵ Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK
⁶ Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg, Germany
⁷ Universitäts-Sternwarte München, Ludwig-Maximilians-Universität, Scheinerstrasse 1, 81679 München, Germany
⁸ SRON Netherlands Institute for Space Research, PO Box 800, 9700 AV Groningen, The Netherlands
⁹ Kapteyn Astronomical Institute, University of Groningen, 9700 AV Groningen, The Netherlands
¹⁰ Department of Earth and Space Science, Indian Institute of Space Science and Technology, Thiruvananthapuram, 695 547 Kerala, India
¹¹ Dublin Institute for Advanced Studies (DIAS), 31 Fitzwilliam Place, Dublin 2, Ireland
¹² Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands

Received: 19 January 2013
Accepted: 15 March 2013

Abstract

We report on ALMA observations of continuum and molecular line emission with 0."4 resolution towards the high-mass star-forming region G35.20–0.74 N. Two dense cores are detected in typical hot-core tracers (e.g., CH₃CN) that reveal velocity gradients. In one of these cores, the velocity field can be fitted with an almost edge-on Keplerian disk rotating about a central mass of  ~18 M_⊙. This finding is consistent with the results of a recent study of the CO first overtone bandhead emission at 2.3 μm towards G35.20–0.74 N. The disk radius and mass are  ≳2500 au and  ~3 M_⊙. To reconcile the observed bolometric luminosity (~3 × 10⁴ L_⊙) with the estimated stellar mass of 18 M_⊙, we propose that the latter is the total mass of a binary system.