| 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]
Companion
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° |
— |
References
- 1 2 3 4 5 6 7 8 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- 1 2 3 4 Anderson, E.; Francis, Ch. (2012-05-01). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. ISSN 1063-7737. S2CID 119257644.
- ↑ Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars, Vol. 5". Michigan Spectral Survey. 05: 0. Bibcode:1999MSS...C05....0H.
- 1 2 3 4 5 6 7 Brewer, John M.; Fischer, Debra A.; Valenti, Jeff A.; Piskunov, Nikolai (2016-08-01). "Spectral Properties of Cool Stars: Extended Abundance Analysis of 1,617 Planet-search Stars". The Astrophysical Journal Supplement Series. 225 (2): 32. arXiv:1606.07929. Bibcode:2016ApJS..225...32B. doi:10.3847/0067-0049/225/2/32. ISSN 0067-0049. S2CID 118507965.
- 1 2 3 4 5 6 Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
- 1 2 3 4 Nordström, B.; Mayor, M.; Andersen, J.; Holmberg, J.; Pont, F.; Jørgensen, B. R.; Olsen, E. H.; Udry, S.; Mowlavi, N. (2004-05-01). "The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of ~14 000 F and G dwarfs". Astronomy and Astrophysics. 418: 989–1019. arXiv:astro-ph/0405198. Bibcode:2004A&A...418..989N. doi:10.1051/0004-6361:20035959. ISSN 0004-6361. S2CID 11027621.
- ↑ Tokovinin, Andrei (2014-04-01). "From Binaries to Multiples. I. Data on F and G Dwarfs within 67 pc of the Sun". The Astronomical Journal. 147 (4): 86. arXiv:1401.6825. Bibcode:2014AJ....147...86T. doi:10.1088/0004-6256/147/4/86. ISSN 0004-6256. S2CID 53965918.
- ↑ Ment, Kristo; Fischer, Debra A.; Bakos, Gaspar; Howard, Andrew W.; Isaacson, Howard (2018-11-01). "Radial Velocities from the N2K Project: Six New Cold Gas Giant Planets Orbiting HD 55696, HD 98736, HD 148164, HD 203473, and HD 211810". The Astronomical Journal. 156 (5): 213. arXiv:1809.01228. Bibcode:2018AJ....156..213M. doi:10.3847/1538-3881/aae1f5. ISSN 0004-6256. S2CID 119243619.
- 1 2 Feng, Fabo; Butler, R. Paul; et al. (August 2022). "3D Selection of 167 Substellar Companions to Nearby Stars". The Astrophysical Journal Supplement Series. 262 (21): 21. arXiv:2208.12720. Bibcode:2022ApJS..262...21F. doi:10.3847/1538-4365/ac7e57. S2CID 251864022.
