http://arxiv.org/abs/1401.2990
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 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 to Sgr A* approximately once per decade. We propose that one of these clumps is the observed G2 cloud, with the rest of the stream being detectable at lower Br-$\gamma$ 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 ~2,000 candidate stars, and by fixing the orbital plane of each candidate star to G2 (as is expected for a tidal disruption), we find that the late-type star S1-34 has an orbit that is compatible with the notion that it was tidally disrupted to produce G2. If S1-34 is indeed the star that was disrupted, it last encountered Sgr A* in the late 18th century, and will likely be disrupted again in several hundred years. However, while S1-34’s orbit is compatible with the giant disruption scenario given its measured position and proper motion, its radial velocity is currently unknown. If S1-34’s radial velocity is measured to be compatible with a disruptive orbit, it would strongly suggest that a tidal disruption of S1-34 produced G2.
Wed, 15 Jan 14
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