V723 Monocerotis
(Redirected from The Unicorn (black hole))
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Monoceros |
| Right ascension | 06h 29m 04.659s[2] |
| Declination | −05° 34′ 20.23″[2] |
| Apparent magnitude (V) | 8.21 - 8.42[3] |
| Characteristics | |
| Spectral type | G0II[4] |
| Variable type | Ellipsoidal[5] |
| Astrometry | |
| Proper motion (μ) | RA: −1.347 mas/yr[2] Dec.: 16.140 mas/yr[2] |
| Parallax (π) | 2.1748 ± 0.0331 mas[2] |
| Distance | 1,500 ± 20 ly (460 ± 7 pc) |
| Absolute magnitude (MV) | +0.93[6] |
| Orbit[1] | |
| Period (P) | 59.9398 d |
| Eccentricity (e) | 0 (fixed) |
| Inclination (i) | 87.0+1.7 −1.4° |
| Argument of periastron (ω) (secondary) | 0 (fixed)° |
| Details | |
| Giant star | |
| Mass | 0.44±0.06[5] M☉ |
| Radius | 22.5±1.0[5] R☉ |
| Luminosity | 173±8[1] L☉ |
| Surface gravity (log g) | 1.7±0.1[1] cgs |
| Temperature | 3,800±100[5] K |
| Metallicity [Fe/H] | −0.9±0.1[1] dex |
| Rotational velocity (v sin i) | 15±2[5] km/s |
| Age | 5.4+5.1 −2.6[1] Gyr |
| Stripped subgiant | |
| Mass | 2.8±0.3[5] M☉ |
| Radius | 8.3±0.4[5] R☉ |
| Temperature | 5,800±200[5] K |
| Rotational velocity (v sin i) | 70±10[5] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
V723 Monocerotis is a variable star in the constellation Monoceros. It was proposed in 2021 to be a binary system including a lower mass gap black hole candidate nicknamed "The Unicorn".[1] Located 1,500 light years from Earth, it would be the closest black hole to our planet, and among the smallest ever found.[8][9]
Located in the Monoceros constellation, V723 Monocerotis is an eighth-magnitude ellipsoidal variable yellow giant star roughly the mass of the Sun, but 25 times its radius. The accompanying black hole was proposed to have a mass 3 times the mass of the Sun, corresponding to a Schwarzschild radius of 9 kilometers.[10][11]
Follow-up work in 2022 argued that V723 Monocerotis does not contain a black hole, but is a mass-transfer binary containing a red giant and a subgiant star that has been stripped of much of its mass.[5]
See also
[edit]References
[edit]- ^ a b c d e f g Jayasinghe, T.; et al. (2021-01-01). "A unicorn in monoceros: The 3 M⊙ dark companion to the bright, nearby red giant V723 Mon is a non-interacting, mass-gap black hole candidate". Monthly Notices of the Royal Astronomical Society. 504 (2): 2577–2602. arXiv:2101.02212. Bibcode:2021MNRAS.504.2577J. doi:10.1093/mnras/stab907.
- ^ a b c d Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
- ^ "V723 Mon". Variable Star Index. Retrieved 2022-03-23.
- ^ Houk, N.; Swift, C. (1999), "Michigan catalogue of two-dimensional spectral types for the HD Stars", Michigan Spectral Survey, 5, Bibcode:1999MSS...C05....0H.
- ^ a b c d e f g h i j El-Badry, Kareem; Seeburger, Rhys; Jayasinghe, Tharindu; Rix, Hans-Walter; Almada, Silvia; Conroy, Charlie; Price-Whelan, Adrian M.; Burdge, Kevin (2022). "Unicorns and giraffes in the binary zoo: Stripped giants with subgiant companions". Monthly Notices of the Royal Astronomical Society. 512 (4): 5620–5641. arXiv:2203.06348. Bibcode:2022MNRAS.512.5620E. doi:10.1093/mnras/stac815.
- ^ Strassmeier, K.; Washuettl, A.; Granzer, Th.; Scheck, M.; Weber, M. (2000). "The Vienna-KPNO search for Doppler-imaging candidate stars. I. A catalog of stellar-activity indicators for 1058 late-type Hipparcos stars". Astronomy and Astrophysics Supplement Series. 142 (2): 275. Bibcode:2000A&AS..142..275S. doi:10.1051/aas:2000328.
- ^ "V723 Mon". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-11-27.
- ^ "Newfound black hole may be the closest to Earth". Science. 2021-04-29. Archived from the original on April 29, 2021. Retrieved 2021-08-09.
- ^ "A black hole dubbed 'the Unicorn' may be galaxy's smallest one". Reuters. 2021-04-22. Retrieved 2021-08-09.
- ^ "Is the "Unicorn" the Closest Black Hole?". Sky & Telescope. 2021-04-23. Retrieved 2021-08-09.
- ^ "Where is the nearest black hole to Earth?". BBC Sky at Night Magazine. Retrieved 2021-08-09.
Further reading
[edit]- Masuda, Kento; Hirano, Teruyuki (April 2021). "Tidal Effects on the Radial Velocities of V723 Mon: Additional Evidence for a Dark 3 M⊙ Companion". The Astrophysical Journal Letters. 910 (2): 10. arXiv:2103.05216. Bibcode:2021ApJ...910L..17M. doi:10.3847/2041-8213/abecdc. S2CID 232168389. L17.
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