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Title: POSSIBLE ORIGIN OF THE G2 CLOUD FROM THE TIDAL DISRUPTION OF A KNOWN GIANT STAR BY SGR A*

The discovery of the gas cloud G2 on a near-radial orbit about Sgr A* has prompted much speculation on its origin. In this Letter, we propose that G2 formed out of the debris stream produced by the removal of mass from the outer envelope of a nearby giant star. We perform hydrodynamical simulations of the returning tidal debris stream with cooling and find that the stream condenses into clumps that fall periodically onto Sgr A*. We propose that one of these clumps is the observed G2 cloud, with the rest of the stream being detectable at lower Brγ emissivity along a trajectory that would trace from G2 to the star that was partially disrupted. By simultaneously fitting the orbits of S2, G2, and ∼2000 candidate stars, and by fixing the orbital plane of each candidate star to G2 (as is expected for a tidal disruption), we find that several stars have orbits that are compatible with the notion that one of them was tidally disrupted to produce G2. If one of these stars were indeed disrupted, it last encountered Sgr A* hundreds of years ago and has likely encountered Sgr A* repeatedly. However, while these stars are compatible with the giant disruption scenario givenmore » their measured positions and proper motions, their radial velocities are currently unknown. If one of these stars' radial velocity is measured to be compatible with a disruptive orbit, it would strongly suggest that its disruption produced G2.« less
Authors:
;  [1] ; ;  [2]
  1. Harvard-Smithsonian Center for Astrophysics, The Institute for Theory and Computation, 60 Garden Street, Cambridge, MA 02138 (United States)
  2. Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)
Publication Date:
OSTI Identifier:
22365868
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 786; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BLACK HOLES; CLOUDS; COMPUTERIZED SIMULATION; EMISSIVITY; GALAXIES; GIANT STARS; GRAVITATION; MASS; ORBITS; PERIODICITY; PROPER MOTION; RADIAL VELOCITY; STREAMS