Tidal Distortion of the Envelope of an AGB Star IRS 3 near Sgr A*

DOI: 
10.3847/1538-4357/aa5ea2
Publication date: 
15/03/2017
Main author: 
Yusef-Zadeh, F
IAA authors: 
Schödel, R.
Authors: 
Yusef-Zadeh, F.; Wardle, M.; Cotton, W.; Schödel, R.; Royster, M. J.; Roberts, D. A.; Kunneriath, D.
Journal: 
The Astrophysical Journal
Refereed: 
Yes
Publication type: 
Article
Volume: 
837
Pages: 
7 pp.
Issue: 
1
Abstract: 

We present radio and millimeter continuum observations of the Galactic center taken with the Very Large Array (VLA) and ALMA at 44 and 226 GHz, respectively. We detect radio and millimeter emission from IRS 3, lying ̃4.″5 NW of Sgr A*, with a spectrum that is consistent with the photospheric emission from an AGB star at the Galactic center. Millimeter images reveal that the envelope of IRS 3, the brightest and most extended 3.8 μm Galactic center stellar source, consists of two semicircular dust shells facing the direction of Sgr A*. The outer circumstellar shell, at a distance of 1.6 × 104 au, appears to break up into “fingers” of dust directed toward Sgr A*. These features coincide with molecular CS (5-4) emission and a near-IR extinction cloud distributed between IRS 3 and Sgr A*. The NE-SW asymmetric shapes of the IRS 3 shells seen at 3.8 μm and radio are interpreted as structures that are tidally distorted by Sgr A*. Using the kinematics of CS emission and the proper motion of IRS 3, the tidally distorted outflowing material from the envelope after 5000 yr constrains the distance of IRS 3 to ̃0.7 pc in front of or ̃0.5 pc behind Sgr A*. This suggests that the mass loss by stars near Sgr A* can supply a reservoir of molecular material near Sgr A*. We also present dark features in radio continuum images coincident with the envelope of IRS 3. These dusty stars provide examples in which high-resolution radio continuum images can identify dust-enshrouded stellar sources embedded in an ionized medium.

Database: 
WOK
SCOPUS
URL: 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015236967&doi=10.3847%2f1538-4357%2faa5ea2&partnerID=40&md5=9da8e2e223f2c7a24ed0c037dfd3d804
ADS Bibcode: 
2017ApJ...837...93Y
Keywords: 
Galaxy: center; Galaxy: nucleus; ISM: clouds; ISM: molecules; ISM: structure; stars: AGB and post-AGB; Astrophysics - Astrophysics of Galaxies; Astrophysics - Solar and Stellar Astrophysics