S62 (star)
S62 is a star in the cluster surrounding Sagittarius A* (Sgr A*), the supermassive black hole in the center of the Milky Way. S62 orbits Sgr A* in 9.9 years, the shortest known (as of August 2019) orbital period of any star around Sgr A*. The previous record holder, S55 has a 12.8-year period.[3]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Sagittarius |
| Right ascension | 17h 45m 40.036s[1] |
| Declination | −29° 00′ 28.17″[1] |
| Orbit[2] | |
| Primary | Sgr A* |
| Companion | S62 |
| Period (P) | 9.9 yr |
| Semi-major axis (a) | 740.1 au |
| Eccentricity (e) | 0.976 |
| Inclination (i) | 72.76° |
| Longitude of the node (Ω) | 122.61° |
| Periastron epoch (T) | 2003.33 |
| Argument of periastron (ω) (secondary) | 42.62° |
| Details | |
| Mass | 6.1[2] M☉ |
| Database references | |
| SIMBAD | data |
In addition, S62 has a highly eccentric orbit which makes it pass very close to Sgr A*, only 16 astronomical units (2.4×109 km), less than the distance between Uranus and the Sun. The star therefore passes only about 215 times the Schwarzschild radius of Sgr A* (the Schwarzschild radius of Sgr A* is approximately 0.082 AU, or 12 million km). It is closer to Sgr A* than the previous record, around 45 AU (6.7 billion km, 550 Schwarzschild radii) held by the star S175, and much closer than the better-studied S2 (118 AU, 18 billion km, 1,440 Schwarzschild radii).[3]
S62 passes so close to Sgr A* that its orbit has a very large precession: its orbit shifts by about 10° with each revolution. At closest approach, its velocity is about 0.10c (10% of the speed of light) relative to Sgr A*. S62's most recent approach to Sgr A* was towards the end of 2022.[3]
The discovery of S62 improved the bounds on the mass distribution in the center of the Galactic Center, showing that (4.15±0.6)×106 M☉ are concentrated within 16 AU of the center, fully consistent with Sgr A* being a supermassive black hole.[3]
References edit
- ^ a b "Sgr A*". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-08-23.
- ^ a b Peißker, Florian; Eckart, Andreas; Zajaček, Michal; Ali, Basel; Parsa, Marzieh (2020). "S62 and S4711: Indications of a Population of Faint Fast-moving Stars inside the S2 Orbit. S4711 on a 7.6 yr Orbit around Sgr A*". The Astrophysical Journal. 899 (1): 50. arXiv:2008.04764. Bibcode:2020ApJ...899...50P. doi:10.3847/1538-4357/ab9c1c. S2CID 221095771.
- ^ a b c d Peissker, Florian; Eckart, Andreas; Parsa, Marzieh (January 2020). "S62 on a 9.9 year orbit around SgrA*". The Astrophysical Journal. 889 (1): 61. arXiv:2002.02341. Bibcode:2020ApJ...889...61P. doi:10.3847/1538-4357/ab5afd. S2CID 211043784.