Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Vulpecula |
Right ascension | 20h 52m 07.68352s [1] |
Declination | 27° 05′ 48.9951″ [1] |
Apparent magnitude (V) | 4.56 [2] |
Characteristics | |
Evolutionary stage | horizontal branch |
Spectral type | G7IIIa Fe-1 Ba [2] |
U−B color index | +0.46 [3] |
B−V color index | +0.82 [3] |
Variable type | suspected [4] |
Astrometry | |
Radial velocity (Rv) | +2.25 [5] km/s |
Proper motion (μ) |
RA: −70.902
[1]
mas/
yr Dec.: −56.360 [1] mas/ yr |
Parallax (π) | 14.2796 ± 0.1864 mas [1] |
Distance | 228 ± 3
ly (70.0 ± 0.9 pc) |
Absolute magnitude (MV) | 0.77 [6] |
Orbit [7] | |
Period (P) | 1,860.6±1.3 d |
Semi-major axis (a) | ≥ 103.0 Gm |
Eccentricity (e) | 0.375±0.009 |
Periastron epoch (T) | 52,316±6 MJD |
Argument of periastron (ω) (secondary) | 15.1±1.4° |
Semi-amplitude (K1) (primary) | 4.34±0.04 km/s |
Details [8] | |
31 Vul A | |
Mass | 2.40±0.05 M☉ |
Radius | 8.01±0.30 R☉ |
Luminosity | 52.53 [2] L☉ |
Surface gravity (log g) | 2.97±0.05 cgs |
Temperature | 5,261±15 K |
Metallicity [Fe/H] | −0.05±0.02 dex |
Rotational velocity (v sin i) | 5.9±0.3 [7] km/s |
Age | 700±40 Myr |
Other designations | |
Database references | |
SIMBAD | data |
31 Vulpeculae is a binary star [7] system in the northern constellation of Vulpecula. It is visible to the naked eye as a faint, yellow-hued point of light with an apparent visual magnitude of 4.56. [2] The system is located approximately 228 light years away from the Sun based on parallax, [1] and it is drifting further away with a radial velocity of +2.25 km/s. [5]
The variable radial velocity of this system was first suspected by German Astronomer Friedrich Küstner in 1914. The system appears as a single-lined spectroscopic binary with an orbital period of 5.1 years and an eccentricity of 0.38. The a sin i value for the primary is 103.0 ± 1.1 Gm (0.69 ± 0.01 AU), [7] where a is the semimajor axis and i is the (unknown) orbital inclination. This value provides a lower bound on the actual semimajor axis for the orbit.
The primary component is an aging giant star with a stellar classification of G7IIIa Fe-1 Ba, [2] indicating a mild barium star with an underabundance of iron. [7] Having exhausted the supply of hydrogen at its core, it has expanded to eight times the Sun's radius. [8] It is a red clump giant, [10] which indicates it is on the horizontal branch and is generating energy through helium fusion at its core. This is a suspected variable star with a magnitude that varies from 3.77 to 4.08 in the I passband. [4] It is about 700 million years old with 2.4 times the mass of the Sun. The star is radiating 53 [2] times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 5,261 K. [8] The companion may be a degenerate white dwarf with about 0.4 M☉. [7]
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Vulpecula |
Right ascension | 20h 52m 07.68352s [1] |
Declination | 27° 05′ 48.9951″ [1] |
Apparent magnitude (V) | 4.56 [2] |
Characteristics | |
Evolutionary stage | horizontal branch |
Spectral type | G7IIIa Fe-1 Ba [2] |
U−B color index | +0.46 [3] |
B−V color index | +0.82 [3] |
Variable type | suspected [4] |
Astrometry | |
Radial velocity (Rv) | +2.25 [5] km/s |
Proper motion (μ) |
RA: −70.902
[1]
mas/
yr Dec.: −56.360 [1] mas/ yr |
Parallax (π) | 14.2796 ± 0.1864 mas [1] |
Distance | 228 ± 3
ly (70.0 ± 0.9 pc) |
Absolute magnitude (MV) | 0.77 [6] |
Orbit [7] | |
Period (P) | 1,860.6±1.3 d |
Semi-major axis (a) | ≥ 103.0 Gm |
Eccentricity (e) | 0.375±0.009 |
Periastron epoch (T) | 52,316±6 MJD |
Argument of periastron (ω) (secondary) | 15.1±1.4° |
Semi-amplitude (K1) (primary) | 4.34±0.04 km/s |
Details [8] | |
31 Vul A | |
Mass | 2.40±0.05 M☉ |
Radius | 8.01±0.30 R☉ |
Luminosity | 52.53 [2] L☉ |
Surface gravity (log g) | 2.97±0.05 cgs |
Temperature | 5,261±15 K |
Metallicity [Fe/H] | −0.05±0.02 dex |
Rotational velocity (v sin i) | 5.9±0.3 [7] km/s |
Age | 700±40 Myr |
Other designations | |
Database references | |
SIMBAD | data |
31 Vulpeculae is a binary star [7] system in the northern constellation of Vulpecula. It is visible to the naked eye as a faint, yellow-hued point of light with an apparent visual magnitude of 4.56. [2] The system is located approximately 228 light years away from the Sun based on parallax, [1] and it is drifting further away with a radial velocity of +2.25 km/s. [5]
The variable radial velocity of this system was first suspected by German Astronomer Friedrich Küstner in 1914. The system appears as a single-lined spectroscopic binary with an orbital period of 5.1 years and an eccentricity of 0.38. The a sin i value for the primary is 103.0 ± 1.1 Gm (0.69 ± 0.01 AU), [7] where a is the semimajor axis and i is the (unknown) orbital inclination. This value provides a lower bound on the actual semimajor axis for the orbit.
The primary component is an aging giant star with a stellar classification of G7IIIa Fe-1 Ba, [2] indicating a mild barium star with an underabundance of iron. [7] Having exhausted the supply of hydrogen at its core, it has expanded to eight times the Sun's radius. [8] It is a red clump giant, [10] which indicates it is on the horizontal branch and is generating energy through helium fusion at its core. This is a suspected variable star with a magnitude that varies from 3.77 to 4.08 in the I passband. [4] It is about 700 million years old with 2.4 times the mass of the Sun. The star is radiating 53 [2] times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 5,261 K. [8] The companion may be a degenerate white dwarf with about 0.4 M☉. [7]