DETECTION OF GALACTIC CENTER SOURCE G2 AT 3.8 mu m DURING PERIAPSE PASSAGE

作者：Witzel G^*; Ghez A M; Morris M R; Sitarski B N; Boehle A; Naoz S; Campbell R; Becklin E E; C****izo G; Chappell S; Do T; Lu J R; Matthews K; Meyer L; Stockton A; Wizinowich P; Yelda S

来源：Astrophysical Journal Letters, 2014, 796(1): L8.

DOI：10.1088/2041-8205/796/1/L8

• black hole physics
• Galaxy: center
• Galaxy: nucleus
• infrared: stars
• techniques: high angular resolution
• techniques: photometric

We report new observations of the Galactic Center source G2 from the W. M. Keck Observatory. G2 is a dusty red object associated with gas that shows tidal interactions as it nears its closest approach with the Galaxy%26apos;s central black hole. Our observations, conducted as G2 passed through periapse, were designed to test the proposal that G2 is a 3 Earth mass gas cloud. Such a cloud should be tidally disrupted during periapse passage. The data were obtained using the Keck II laser guide star adaptive optics system (LGSAO) and the facility near-infrared camera (NIRC2) through the K%26apos; [2.1 mu m] and L%26apos; [3.8 mu m] broadband filters. Several results emerge from these observations: (1) G2 has survived its closest approach to the black hole as a compact, unresolved source at L%26apos;, (2) G2%26apos;s L%26apos; brightness measurements are consistent with those over the last decade, (3) G2%26apos;s motion continues to be consistent with a Keplerian model. These results rule out G2 as a pure gas cloud and imply that G2 has a central star. This star has a luminosity of similar to 30 L-circle dot and is surrounded by a large (similar to 2.6 AU) optically thick dust shell. The differences between the L%26apos; and Br-gamma observations can be understood with a model in which L%26apos; and Br-gamma emission arises primarily from internal and external heating, respectively. We suggest that G2 is a binary star merger product and will ultimately appear similar to the B-stars that are tightly clustered around the black hole (the so-called S-star cluster).

• 出版日期2014-11-20