Gaia BH2
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Centaurus |
| Right ascension | 13h 50m 16.748s[1] |
| Declination | −59° 14′ 20.33″[1] |
| Apparent magnitude (V) | 12.711[2] |
| Characteristics | |
| Red giant | |
| Evolutionary stage | Red giant |
| Black hole | |
| Evolutionary stage | Stellar black hole |
| Astrometry | |
| Radial velocity (Rv) | −5.04±2.08[1] km/s |
| Proper motion (μ) | RA: −10.48±0.1 mas/yr[3] Dec.: −4.61±0.06 mas/yr[3] |
| Parallax (π) | 0.859 ± 0.018 mas[3] |
| Distance | 3,800 ± 80 ly (1,160 ± 20 pc) |
| Orbit[3] | |
| Period (P) | 1,276.7±0.6 d |
| Semi-major axis (a) | 4.96±0.08 AU |
| Eccentricity (e) | 0.5176±0.0009 |
| Inclination (i) | 34.87±0.34° |
| Longitude of the node (Ω) | 266.9±0.5° |
| Periastron epoch (T) | 2457438.3±1.4 |
| Argument of periastron (ω) (secondary) | 130.9±0.4° |
| Semi-amplitude (K1) (primary) | 25.23±0.04 km/s |
| Details[3] | |
| Red giant | |
| Mass | 1.07±0.19 M☉ |
| Radius | 7.77±0.25 R☉ |
| Luminosity (bolometric) | 24.6±1.6 L☉ |
| Surface gravity (log g) | 2.71±0.24 cgs |
| Temperature | 4,604±87 K |
| Metallicity [Fe/H] | −0.22±0.02 dex |
| Rotational velocity (v sin i) | <1.5 km/s |
| Black hole | |
| Mass | 8.94±0.34 M☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
Gaia BH2 (Gaia DR3 5870569352746779008) is a binary system consisting of a red giant and what is very likely a stellar-mass black hole. Gaia BH2 is located about 3,800 light years away (1.16 kpc away) in the constellation of Centaurus, making it as of 2024[update] the third-closest known black hole system to Earth. Gaia BH2 is the second black hole discovered from Gaia DR3 astrometric data.[3]
The black hole and red giant orbit the system barycentre every 1,277 days, or around 3.5 years, with a moderate eccentricity of 0.518. The black hole's mass is around 8.94 M☉, which means its Schwarzschild radius should be about 26.4 km (16.4 mi). The red giant has a mass of 1.07 M☉ and a radius of 7.77 R☉. Its temperature is estimated at 4,604 K (4,331 °C; 7,828 °F).[3]
Discovery
[edit]Gaia BH2 was originally discovered as a black hole binary candidate in 2022, found via astrometric observations with Gaia, along with Gaia BH1. At that time it was not clear if Gaia BH2 did definitely harbour a black hole, but it was the only plausible candidate in the Gaia data other than Gaia BH1.[4][5] Later radial velocity observations confirmed this black hole system and refined its orbital parameters.[3]
References
[edit]- ^ a b c Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ Zacharias, N.; Finch, C. T.; Girard, T. M.; Henden, A.; Bartlett, J. L.; Monet, D. G.; Zacharias, M. I. (2012-07-01). "VizieR Online Data Catalog: UCAC4 Catalogue (Zacharias+, 2012)". VizieR Online Data Catalog: I/322A. Bibcode:2012yCat.1322....0Z.
- ^ a b c d e f g El-Badry, Kareem; Rix, Hans-Walter; Cendes, Yvette; Rodriguez, Antonio C.; Conroy, Charlie; Quataert, Eliot; Hawkins, Keith; Zari, Eleonora; Hobson, Melissa; Breivik, Katelyn; Rau, Arne; Berger, Edo; Shahaf, Sahar; Seeburger, Rhys; Burdge, Kevin B. (2023-02-01). "A red giant orbiting a black hole". Monthly Notices of the Royal Astronomical Society. 521 (3): 4323–4348. arXiv:2302.07880. Bibcode:2023MNRAS.521.4323E. doi:10.1093/mnras/stad799.
- ^ El-Badry, Kareem; Rix, Hans-Walter; Quataert, Eliot; Howard, Andrew W.; Isaacson, Howard; Fuller, Jim; Hawkins, Keith; Breivik, Katelyn; Wong, Kaze W. K.; Rodriguez, Antonio C.; Conroy, Charlie; Shahaf, Sahar; Mazeh, Tsevi; Arenou, Frédéric; Burdge, Kevin B. (2023-01-01). "A Sun-like star orbiting a black hole". Monthly Notices of the Royal Astronomical Society. 518 (1): 1057–1085. arXiv:2209.06833. Bibcode:2023MNRAS.518.1057E. doi:10.1093/mnras/stac3140. ISSN 0035-8711.
- ^ Tanikawa, Ataru; Hattori, Kohei; et al. (September 2022). "Search for a Black Hole Binary in Gaia DR3 Astrometric Binary Stars with Spectroscopic Data". The Astrophysical Journal. 946 (2): 79. arXiv:2209.05632. Bibcode:2023ApJ...946...79T. doi:10.3847/1538-4357/acbf36.
