HD 203473

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 –61.85 km/s.[1] As of 2014, no stellar companions have been detected around the star.[6]

HD 203473
Observation data
Epoch J2000      Equinox J2000.0 (ICRS)
Constellation Equuleus
Right ascension 21h 22m 18.87s[1]
Declination +05° 01′ 24.92″[1]
Apparent magnitude (V) 8.23[2]
Characteristics
Spectral type G6 V[3]
B−V color index +0.66[2]
Astrometry
Radial velocity (Rv)−61.85[1] km/s
Proper motion (μ) RA: 181.478 mas/yr[1]
Dec.: −1.331 mas/yr[1]
Parallax (π)13.7379 ± 0.0570 mas[1]
Distance237.4 ± 1.0 ly
(72.8 ± 0.3 pc)
Absolute magnitude (MV)+4.2[2]
Details
Mass0.82[4] M☉
Radius1.48+0.05
−0.02[1] R☉
Luminosity2.31±0.01[1] L☉
Surface gravity (log g)4.25[4] cgs
Temperature5847+35
−94[1] K
Metallicity [Fe/H]+0.18[4] dex
Rotational velocity (v sin i)1[5] km/s
Age5.2[4] or 8.5[5] Gyr
Other designations
AG+04° 2898, BD+04° 4656, HD 203473, HIP 105521, SAO 126740, GSC 00536-00696
Database references
SIMBADdata
Exoplanet Archivedata
Extrasolar Planets
Encyclopaedia		data

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.[1] This star is over luminous and hot for its class, with it radiating at 2.31 the luminosity of the Sun[1] and an effective temperature of 5,847 K.[1] HD 203473 has different age estimates, either being 5[4] or 8[5] billion years old. The higher luminosity and low projected rotational velocity of 1 km/s[5] 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]

Planetary System

In 2018, the N2K projecy discovered a planet orbiting the star via Doppler spectroscopy. Since the planet was discovered that way, its inclination and true mass is unknown.[7]

The HD 203473 planetary system[7]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b ≥7.8±1.1 MJ 2.73 ± 0.17 1,553 ± 3 0.29 ± 0.01 — —

See also

References
  1. 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.
  2. 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.
  3. 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.
  4. 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.
  5. 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.
  6. 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.
  7. 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.
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