Astronomy:Gaia BH2
250px DECaPS image of Gaia BH2 (star at the center) | |
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Centaurus[1] |
| Right ascension | 13h 50m 16.748s[2] |
| Declination | −59° 14′ 20.33″[2] |
| Apparent magnitude (V) | 12.711[3] |
| Characteristics | |
| Red giant | |
| Evolutionary stage | Red giant branch[2] |
| Black hole | |
| Evolutionary stage | Stellar black hole[4] |
| Astrometry | |
| Radial velocity (Rv) | −5.04±2.08[2] km/s |
| Proper motion (μ) | RA: −10.48±0.1[4] mas/yr Dec.: −4.61±0.06[4] mas/yr |
| Parallax (π) | 0.859 ± 0.018[4] mas |
| Distance | 3,800 ± 80 ly (1,160 ± 20 pc) |
| Orbit[4] | |
| Period (P) | 1,276.7±0.6 d |
| Semi-major axis (a) | 4.96±0.08 astronomical unit|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 | |
| Red giant | |
| Mass | 1.17±0.08[5] M☉ |
| Radius | 8.55+0.20 −0.15[5] R☉ |
| Luminosity (bolometric) | 24.6±1.6[4] L☉ |
| Surface gravity (log g) | 2.71±0.24[4] cgs |
| Temperature | 4,604±87[4] K |
| Metallicity [Fe/H] | −0.22±0.02[4] dex |
| Rotation | 398±5[5] days (preliminary estimate) |
| Rotational velocity (v sin i) | <1.5[4] km/s |
| Age | 5.1+1.2 −1.8[5] Gyr |
| Black hole | |
| Mass | 8.94±0.34[4] M☉ |
| Other designations | |
Gaia BH2, UCAC4 154-126202, 2MASS J13501675-5914203, Gaia DR3 5870569352746779008 | |
| Database references | |
| SIMBAD | data |
Gaia BH2 (Gaia DR3 5870569352746779008) is a binary system consisting of a red giant and 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.[4]
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).[4] The red giant has a mass of 1.17 M☉ and a radius of 8.6 R☉.[5] Its temperature is estimated at 4,604 K (4,331 °C; 7,828 °F).[4] The star is enriched in alpha elements, thus is believed to have undergone mass transfer with another star.[4]
Discovery
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.[6][7] Later radial velocity observations confirmed this black hole system and refined its orbital parameters.[4]
See also
References
- ↑ Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific 99 (617): 695. doi:10.1086/132034. Bibcode: 1987PASP...99..695R Constellation record for this object at VizieR.
- ↑ 2.0 2.1 2.2 2.3 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 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.
- ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 4.14 El-Badry, Kareem; Rix, Hans-Walter; Cendes, Yvette; Rodriguez, Antonio C.; Conroy, Charlie; Quataert, Eliot; Hawkins, Keith; Zari, Eleonora et al. (2023-02-01). "A red giant orbiting a black hole". Monthly Notices of the Royal Astronomical Society 521 (3): 4323–4348. doi:10.1093/mnras/stad799. Bibcode: 2023MNRAS.521.4323E.
- ↑ 5.0 5.1 5.2 5.3 5.4 Hey, Daniel; Li, Yaguang; Ong, Joel (2025-03-12). "Asteroseismology of the red giant companions to Gaia BH2 and BH3". arXiv:2503.09690 [astro-ph.SR].
- ↑ El-Badry, Kareem; Rix, Hans-Walter; Quataert, Eliot; Howard, Andrew W.; Isaacson, Howard; Fuller, Jim; Hawkins, Keith; Breivik, Katelyn et al. (2023-01-01). "A Sun-like star orbiting a black hole". Monthly Notices of the Royal Astronomical Society 518 (1): 1057–1085. doi:10.1093/mnras/stac3140. ISSN 0035-8711. Bibcode: 2023MNRAS.518.1057E.
- ↑ 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. doi:10.3847/1538-4357/acbf36. Bibcode: 2023ApJ...946...79T.
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