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]