SINFONI in the Galactic Center: Young Stars and Infrared Flares in the Central Light‐Monthстатья из журнала
Аннотация: We report on 75 mas resolution, near-IR imaging spectroscopy within the central 30 lt-days of the Galactic center, taken with the new adaptive optics-assisted integral-field spectrometer SINFONI on the ESO VLT. To a limiting magnitude of K ~ 16, 9 of 10 stars in the central 04, and 13 of 17 stars out to 07 from the central black hole have spectral properties of B0-B9 main-sequence stars. Based on the 2.1127 μm He I line width, all brighter early-type stars have normal rotation velocities, similar to solar neighborhood stars. We combine the new radial velocities with SHARP/NACO astrometry to derive improved three-dimensional stellar orbits for six of these "S stars" in the central 05. Their orientations in space appear random. Their orbital planes are not co-aligned with those of the two disks of massive young stars 1''-10'' from Sgr A*. We can thus exclude the hypothesis that the S stars as a group inhabit the inner regions of these disks. They also cannot have been located/formed in these disks and then migrated inward within their planes. From the combination of their normal rotation and random orbital orientations, we conclude that the S stars were most likely brought into the central light-month by strong individual scattering events. The updated estimate of distance to the Galactic center from the S2 orbit fit is R0 = 7.62 ± 0.32 kpc, resulting in a central mass value of (3.61 ± 0.32) × 106 M☉. We happened to catch two smaller flaring events from Sgr A* during our spectral observations. The 1.7-2.45 μm spectral energy distributions of these flares are fit by a featureless, "red" power law of spectral index α' = -4 ± 1 (Sν ~ ν). The observed spectral slope is in good agreement with synchrotron models in which the infrared emission comes from accelerated, nonthermal, high-energy electrons in a radiatively inefficient accretion flow in the central R ~ 10RS region.
Год издания: 2005
Авторы: F. Eisenhauer, R. Genzel, Tal Alexander, R. Abuter, T. Paumard, Thomas Ott, A. Gilbert, S. Gillessen, M. Horrobin, Sascha Trippe, H. Bonnet, Christophe Dumas, N. Hubin, A. Kaufer, M. Kissler‐Patig, G. Monnet, Stefan Ströbele, T. Szeifert, A. Eckart, R. Schödel, S. Zucker
Издательство: IOP Publishing
Источник: The Astrophysical Journal
Ключевые слова: Astrophysical Phenomena and Observations, Astrophysics and Star Formation Studies, Stellar, planetary, and galactic studies
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Открытый доступ: bronze
Том: 628
Выпуск: 1
Страницы: 246–259