Astronomy:V723 Monocerotis
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| 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[2] mas/yr Dec.: 16.140[2] mas/yr |
| Parallax (π) | 2.1748 ± 0.0331[2] mas |
| 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[5] | |
| Stripped giant star | |
| Mass | 0.44±0.06 M☉ |
| Radius | 22.5±1.0 R☉ |
| Luminosity | 105 L☉ |
| Surface gravity (log g) | 1.3 cgs |
| Temperature | 3,800±100 K |
| Metallicity [Fe/H] | −0.5 dex |
| Rotational velocity (v sin i) | 15±2 km/s |
| Age | 5.4+5.1 −2.6[1] Gyr |
| Subgiant | |
| Mass | 2.8±0.3 M☉ |
| Radius | 8.3±0.4 R☉ |
| Luminosity | 70 L☉ |
| Surface gravity (log g) | ~3 cgs |
| Temperature | 5,800±200 K |
| Rotational velocity (v sin i) | 70±10 km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
V723 Monocerotis is a binary star in the constellation Monoceros. It is an ellipsoidal variable about 1,500 light-years distant, too faint to be seen to the naked eye, with a variable apparent magnitude between 8.21 and 8.42.
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 known black hole, and among the smallest ever found[8][9] with 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 that has been stripped of much of its mass, and a subgiant star.[5] The primary red giant star has 25 times the Sun's radius but an unusually low mass of 0.44 solar masses due to mass transfer to its partner. The secondary star is 2.8 times more massive than the Sun and 8.3 times larger, a subgiant approaching the base of the red giant branch. The primary is more than a 100 times as luminous as the Sun, while the secondary is about 70 times as luminous.[5]
References
- ↑ 1.0 1.1 1.2 1.3 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. doi:10.1093/mnras/stab907. Bibcode: 2021MNRAS.504.2577J.
- ↑ 2.0 2.1 2.2 2.3 Brown, A. G. A. (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics 649: A1. doi:10.1051/0004-6361/202039657. Bibcode: 2021A&A...649A...1G. Gaia EDR3 record for this source at VizieR.
- ↑ "V723 Mon". https://www.aavso.org/vsx/index.php?view=detail.top&oid=19551.
- ↑ Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars". Michigan Spectral Survey 5. Bibcode: 1999MSS...C05....0H.
- ↑ 5.0 5.1 5.2 5.3 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. doi:10.1093/mnras/stac815. Bibcode: 2022MNRAS.512.5620E.
- ↑ 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. doi:10.1051/aas:2000328. Bibcode: 2000A&AS..142..275S.
- ↑ "V723 Mon". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=V723+Mon.
- ↑ "Newfound black hole may be the closest to Earth" (in en). 2021-04-29. https://www.nationalgeographic.com/science/article/newfound-black-hole-may-be-the-closest-to-earth.
- ↑ "A black hole dubbed 'the Unicorn' may be galaxy's smallest one". 2021-04-22. https://www.reuters.com/lifestyle/science/black-hole-dubbed-the-unicorn-may-be-galaxys-smallest-one-2021-04-22/.
- ↑ "Is the "Unicorn" the Closest Black Hole?" (in en-US). 2021-04-23. https://skyandtelescope.org/astronomy-news/unicorn-closest-black-hole/.
- ↑ "Where is the nearest black hole to Earth?" (in en). 26 February 2021. https://www.skyatnightmagazine.com/space-science/where-is-nearest-black-hole/.
Further reading
- 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. doi:10.3847/2041-8213/abecdc. L17. Bibcode: 2021ApJ...910L..17M.
 |  |
