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

Abstract

We present radio and mm continuum observations of the Galactic center taken with the VLA and ALMA at 44 and 226 GHz, respectively. We detect radio and mm 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$\mu$m Galactic center stellar source, consists of two semi-circular dust shells facing the direction of Sgr A*. The outer circumstellar shell at the distance of 1.6$\times 10^4$ 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 shape of the IRS 3 shells seen at 3.8 micron 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 years constrains the distance of IRS 3 to $\sim$0.7 pc in front of or $\sim$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 an ionized medium.

arXiv comment16 pages, 5 figures, ApJ (in press)

References in corpus (18)

• A computer program for fast non-LTE analysis of interstellar line spectra
• A gas cloud on its way towards the super-massive black hole in the Galactic Centre
• The nuclear star cluster of the Milky Way: proper motions and mass
• Gas infall towards Sgr A* from the clumpy circumnuclear disk
• New observations of the gas cloud G2 in the Galactic Center
• Molecular abundances in carbon-rich circumstellar envelopes
• Surviving the hole I: Spatially resolved chemistry around Sgr A*
• Stellar Bowshocks in the Northern Arm of the Galactic Center: More Members and Kinematics of the Massive Star Population
• L- and M-band imaging observations of the Galactic Center region
• Infrared H3+ and CO Studies of the Galactic Core: GCIRS 3 and GCIRS 1W
• IRS 13N: a new comoving group of sources at the Galactic Center
• ALMA Observations of the Galactic Center: SiO Outflows and High Mass Star Formation near Sgr A*
• Compact Radio Sources within 30" of Sgr A*: Proper Motions, Stellar Winds and the Accretion Rate onto Sgr A*
• New Measurements of the Radio Photosphere of Mira based on Data from the JVLA and ALMA
• Sgr A* and its Environment: Low Mass Star Formation, the Origin of X-ray Gas and Collimated Outflow
• The OH-streamer in Sgr A revisited: analysis of hydroxyl absorption within 10 pc from the Galactic centre
• First VLTI infrared spectro-interferometry on GCIRS 7 - Characterizing the prime reference source for Galactic center observations at highest angular resolution
• Imprints of Molecular Clouds in Radio Continuum Images

Cited by in corpus (6)

• The Milky Way's Supermassive Black Hole: How good a case is it? A Challenge for Astrophysics & Philosophy of Science
• An Adaptive Optics Survey of Stellar Variability at the Galactic Center
• Radio Stars: from kHz to THz
• Mid-Infrared studies of dusty sources in the Galactic Center
• Red giant - jet collisions in galactic nuclei I: 3D hydrodynamical model of a few stellar orbits
• The Galactic Center in Color: Measuring Extinction with High-Proper-Motion Stars