Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Hydra |
Right ascension | 08h 46m 22.53544s [1] |
Declination | −13° 32′ 51.7502″ [1] |
Apparent magnitude (V) | 4.32 [2] |
Characteristics | |
Spectral type | G8 IIIb CN-1 [3] |
B−V color index | 0.900±0.015 [2] |
Astrometry | |
Radial velocity (Rv) | −8.5±0.7 [2] km/s |
Proper motion (μ) |
RA: +18.789
[1]
mas/
yr Dec.: −18.385 [1] mas/ yr |
Parallax (π) | 16.1839 ± 0.6646 mas [1] |
Distance | 202 ± 8
ly (62 ± 3 pc) |
Absolute magnitude (MV) | +0.26 [4] |
Orbit [5] | |
Primary | Aa |
Companion | Ab |
Period (P) | 1,592±806 d |
Semi-major axis (a) | 0.0116±0.057″ |
Eccentricity (e) | 0.40±0.26 |
Inclination (i) | 58±10° |
Longitude of the node (Ω) | 91±16° |
Periastron epoch (T) | 49,194±664 |
Argument of periastron (ω) (secondary) | 103±34° |
Details | |
Mass | 2.32 [6] M☉ |
Radius | 11.51+0.18 −0.37 [1] R☉ |
Luminosity | 77.468±3.553 [1] L☉ |
Temperature | 4,968±13 [6] K |
Rotational velocity (v sin i) | 4.6±0.2 [4] km/s |
Age | 910 [6] Myr |
Other designations | |
Database references | |
SIMBAD | data |
12 Hydrae is a probable astrometric binary [8] star system located 202 light years away from the Sun in the equatorial constellation of Hydra. It has the Bayer designation D Hydrae; [7] 12 Hydrae is the Flamsteed designation. This system is visible to the naked eye as a faint, yellow-hued star with a combined apparent visual magnitude of 4.32. [2] It is moving closer to the Earth with a heliocentric radial velocity of −8.5 km/s. [2]
This was found to be a double star by R. A. Rossiter in 1953, [9] with the magnitude 13.7 companion having an angular separation of 26.8 ″ along a position angle of 266°, as of 2016. The brighter, magnitude 4.32 component A is a spectroscopic binary. As of 2009, the orbital solution for this pair is of low quality, giving a period of roughly 4 years and an eccentricity of around 0.4. [5]
The primary component is an aging giant star with a stellar classification of G8 IIIb CN-1, [3] where the suffix notation indicates an underabundance of the cyanogen molecule. It is 910 [6] million years old with 2.32 [6] times the mass of the Sun. After exhausting the hydrogen at its core and evolving off the main sequence, the star has swollen to 11.5 [1] times the Sun's radius. It is radiating 77 [1] times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,968 K. [6]
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Hydra |
Right ascension | 08h 46m 22.53544s [1] |
Declination | −13° 32′ 51.7502″ [1] |
Apparent magnitude (V) | 4.32 [2] |
Characteristics | |
Spectral type | G8 IIIb CN-1 [3] |
B−V color index | 0.900±0.015 [2] |
Astrometry | |
Radial velocity (Rv) | −8.5±0.7 [2] km/s |
Proper motion (μ) |
RA: +18.789
[1]
mas/
yr Dec.: −18.385 [1] mas/ yr |
Parallax (π) | 16.1839 ± 0.6646 mas [1] |
Distance | 202 ± 8
ly (62 ± 3 pc) |
Absolute magnitude (MV) | +0.26 [4] |
Orbit [5] | |
Primary | Aa |
Companion | Ab |
Period (P) | 1,592±806 d |
Semi-major axis (a) | 0.0116±0.057″ |
Eccentricity (e) | 0.40±0.26 |
Inclination (i) | 58±10° |
Longitude of the node (Ω) | 91±16° |
Periastron epoch (T) | 49,194±664 |
Argument of periastron (ω) (secondary) | 103±34° |
Details | |
Mass | 2.32 [6] M☉ |
Radius | 11.51+0.18 −0.37 [1] R☉ |
Luminosity | 77.468±3.553 [1] L☉ |
Temperature | 4,968±13 [6] K |
Rotational velocity (v sin i) | 4.6±0.2 [4] km/s |
Age | 910 [6] Myr |
Other designations | |
Database references | |
SIMBAD | data |
12 Hydrae is a probable astrometric binary [8] star system located 202 light years away from the Sun in the equatorial constellation of Hydra. It has the Bayer designation D Hydrae; [7] 12 Hydrae is the Flamsteed designation. This system is visible to the naked eye as a faint, yellow-hued star with a combined apparent visual magnitude of 4.32. [2] It is moving closer to the Earth with a heliocentric radial velocity of −8.5 km/s. [2]
This was found to be a double star by R. A. Rossiter in 1953, [9] with the magnitude 13.7 companion having an angular separation of 26.8 ″ along a position angle of 266°, as of 2016. The brighter, magnitude 4.32 component A is a spectroscopic binary. As of 2009, the orbital solution for this pair is of low quality, giving a period of roughly 4 years and an eccentricity of around 0.4. [5]
The primary component is an aging giant star with a stellar classification of G8 IIIb CN-1, [3] where the suffix notation indicates an underabundance of the cyanogen molecule. It is 910 [6] million years old with 2.32 [6] times the mass of the Sun. After exhausting the hydrogen at its core and evolving off the main sequence, the star has swollen to 11.5 [1] times the Sun's radius. It is radiating 77 [1] times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,968 K. [6]