ZAJAČEK, Michal and Arman TURSUNOV. A stellar fly-by close to the Galactic center: Can we detect stars on highly relativistic orbits? Astronomische Nachrichten. 2018, vol. 339, No 5, p. 324-330. ISSN 0004-6337. Available from: https://dx.doi.org/10.1002/asna.201813499.
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Basic information
Original name A stellar fly-by close to the Galactic center: Can we detect stars on highly relativistic orbits?
Authors ZAJAČEK, Michal (703 Slovakia) and Arman TURSUNOV (203 Czech Republic, guarantor, belonging to the institution).
Edition Astronomische Nachrichten, 2018, 0004-6337.
Other information
Original language English
Type of outcome Article in a journal
Field of Study 10308 Astronomy
Country of publisher Germany
Confidentiality degree is not subject to a state or trade secret
WWW URL
RIV identification code RIV/47813059:19240/18:A0000259
Organization unit Faculty of Philosophy and Science in Opava
Doi http://dx.doi.org/10.1002/asna.201813499
UT WoS 000444072500002
Keywords in English celestial mechanics; galaxy: center; methods: statistical; stellar dynamics
Tags International impact, Reviewed
Links GJ16-03564Y, research and development project.
Changed by Changed by: RNDr. Arman Tursunov, Ph.D., učo 39715. Changed: 23/4/2020 14:02.
Abstract
The Galactic center Nuclear Star Cluster is one of the densest stellar clusters in the Galaxy. The stars in its inner portions orbit the supermassive black hole associated with the compact radio source Sgr A* at the orbital speeds of several thousand kilometers per second. The B-type star S2 is currently the best case to test the general relativity as well as other theories of gravity, based on its stellar orbit. Yet, its orbital period of approximate to 16years and the eccentricity of approximate to 0.88 yields the relativistic pericenter shift of approximate to 11', which is observationally still difficult to reliably measure due to possible Newtonian perturbations as well as reference-frame uncertainties. A naive way to solve this problem is to find stars with smaller pericenter distances, r_p <~ 1529 Schwarzschild radii (120 AU), and thus with more prominent relativistic effects. In this paper, we show that to detect stars on relativistic orbits is progressively less likely, given the volume shrinkage and the expected stellar density distributions. Finally, one arrives at a sparse region where the total number of bright stars is expected to fall below 1. One can, however, still potentially detect stars crossing this region. In this paper, we provide a simple formula for the detection probability of a star crossing a sparse region. We also examine an approximate timescale in which the star reappears in the sparse region, i.e., a 'waiting' timescale for observers.
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