Observation data Epoch J2000 Equinox J2000.0 ( ICRS) | |
---|---|
Constellation | Equuleus |
Right ascension | 21h 22m 18.87390s [1] |
Declination | +05° 01′ 24.9072″ [1] |
Apparent magnitude (V) | 8.23 [2] |
Characteristics | |
Spectral type | G6 V [3] |
B−V color index | +0.66 [2] |
Astrometry | |
Radial velocity (Rv) | −61.70±0.13 [1] km/s |
Proper motion (μ) |
RA: 180.093±0.035
mas/
yr
[1] Dec.: 0.098±0.031 mas/ yr [1] |
Parallax (π) | 13.7402 ± 0.0370 mas [1] |
Distance | 237.4 ± 0.6
ly (72.8 ± 0.2 pc) |
Absolute magnitude (MV) | +4.2 [2] |
Details | |
Mass | 0.82 [4] M☉ |
Radius | 1.48+0.05 −0.02 [5] R☉ |
Luminosity | 2.31±0.01 [5] L☉ |
Surface gravity (log g) | 4.25 [4] cgs |
Temperature | 5847+35 −94 [5] K |
Metallicity [Fe/H] | +0.18 [4] dex |
Rotational velocity (v sin i) | 1 [6] km/s |
Age | 5.2 [4] or 8.5 [6] Gyr |
Other designations | |
Database references | |
SIMBAD | data |
Exoplanet Archive | data |
HD 203473 is a star in the equatorial constellation Equuleus. With an apparent magnitude of 8.23, [2] it’s only visible by using an amateur telescope. The star is located at a distance of 237 light years [1] based on its parallax shift but is drifting closer at a high rate of 61.7 km/s. [1] As of 2014, no stellar companions have been detected around the star. [7]
HD 203473 is an ordinary G-type main-sequence star with 82% the mass of the Sun, [4] but is 48% larger than the latter. [5] This star is over luminous and hot for its class, with it radiating at 2.31 the luminosity of the Sun [5] and an effective temperature of 5,847 K. [5] HD 203473 has different age estimates, either being 5 [4] or 8 [6] billion years old. The higher luminosity and low projected rotational velocity of 1 km/s [6] favors the older age estimate. Like many planetary hosts, HD 203473 has an enhanced metallicity, with an iron abundance 1.51 times that of the Sun. [4]
In 2018, the N2K project discovered an object, initially thought to be a planet, orbiting the star via Doppler spectroscopy. Due to the detection method, its inclination and true mass were initially unknown. [8] In 2022, the inclination and true mass of this companion were measured via astrometry, revealing it to be 96 MJ and thus either a massive brown dwarf or low-mass star. The companion's orbital period was also found to be twice as long as originally thought. [9]
Companion (in order from star) |
Mass |
Semimajor axis ( AU) |
Orbital period ( years) |
Eccentricity | Inclination | Radius |
---|---|---|---|---|---|---|
b | 95.886+8.523 −8.864 MJ |
4.161+0.172 −0.190 |
8.103+0.014 −0.016 |
0.404±0.007 | 141.240+0.949 −0.909 ° |
— |
Observation data Epoch J2000 Equinox J2000.0 ( ICRS) | |
---|---|
Constellation | Equuleus |
Right ascension | 21h 22m 18.87390s [1] |
Declination | +05° 01′ 24.9072″ [1] |
Apparent magnitude (V) | 8.23 [2] |
Characteristics | |
Spectral type | G6 V [3] |
B−V color index | +0.66 [2] |
Astrometry | |
Radial velocity (Rv) | −61.70±0.13 [1] km/s |
Proper motion (μ) |
RA: 180.093±0.035
mas/
yr
[1] Dec.: 0.098±0.031 mas/ yr [1] |
Parallax (π) | 13.7402 ± 0.0370 mas [1] |
Distance | 237.4 ± 0.6
ly (72.8 ± 0.2 pc) |
Absolute magnitude (MV) | +4.2 [2] |
Details | |
Mass | 0.82 [4] M☉ |
Radius | 1.48+0.05 −0.02 [5] R☉ |
Luminosity | 2.31±0.01 [5] L☉ |
Surface gravity (log g) | 4.25 [4] cgs |
Temperature | 5847+35 −94 [5] K |
Metallicity [Fe/H] | +0.18 [4] dex |
Rotational velocity (v sin i) | 1 [6] km/s |
Age | 5.2 [4] or 8.5 [6] Gyr |
Other designations | |
Database references | |
SIMBAD | data |
Exoplanet Archive | data |
HD 203473 is a star in the equatorial constellation Equuleus. With an apparent magnitude of 8.23, [2] it’s only visible by using an amateur telescope. The star is located at a distance of 237 light years [1] based on its parallax shift but is drifting closer at a high rate of 61.7 km/s. [1] As of 2014, no stellar companions have been detected around the star. [7]
HD 203473 is an ordinary G-type main-sequence star with 82% the mass of the Sun, [4] but is 48% larger than the latter. [5] This star is over luminous and hot for its class, with it radiating at 2.31 the luminosity of the Sun [5] and an effective temperature of 5,847 K. [5] HD 203473 has different age estimates, either being 5 [4] or 8 [6] billion years old. The higher luminosity and low projected rotational velocity of 1 km/s [6] favors the older age estimate. Like many planetary hosts, HD 203473 has an enhanced metallicity, with an iron abundance 1.51 times that of the Sun. [4]
In 2018, the N2K project discovered an object, initially thought to be a planet, orbiting the star via Doppler spectroscopy. Due to the detection method, its inclination and true mass were initially unknown. [8] In 2022, the inclination and true mass of this companion were measured via astrometry, revealing it to be 96 MJ and thus either a massive brown dwarf or low-mass star. The companion's orbital period was also found to be twice as long as originally thought. [9]
Companion (in order from star) |
Mass |
Semimajor axis ( AU) |
Orbital period ( years) |
Eccentricity | Inclination | Radius |
---|---|---|---|---|---|---|
b | 95.886+8.523 −8.864 MJ |
4.161+0.172 −0.190 |
8.103+0.014 −0.016 |
0.404±0.007 | 141.240+0.949 −0.909 ° |
— |