HD 216770
Observation data
Epoch J2000      Equinox J2000
Constellation Piscis Austrinus
Right ascension 22h 55m 53.708s[1]
Declination –26° 39′ 31.54″[1]
Apparent magnitude (V) 8.11[2]
Characteristics
Spectral type K0V[2] or G9VCN+1[3]
B−V color index 0.821[2]
Astrometry
Radial velocity (Rv)31.141±0.0004[4] km/s
Proper motion (μ) RA: 226.237 mas/yr[1]
Dec.: −177.985 mas/yr[1]
Parallax (π)27.2923 ± 0.0245 mas[1]
Distance119.5 ± 0.1 ly
(36.64 ± 0.03 pc)
Absolute magnitude (MV)5.22[2]
Details
Mass0.74±0.07[5] M☉
Radius0.93±0.02[5] R☉
Luminosity0.79[2] L☉
Surface gravity (log g)4.37±0.04[5] cgs
Temperature5,399±18[5] K
Metallicity [Fe/H]0.27[5] dex
Rotation35.6 d[2]
Rotational velocity (v sin i)1.4[2] km/s
Age3.1[2] Gyr
Other designations
CD−27°16109, GC 31973, HIP 113238, SAO 191502, LTT 9276, NLTT 55283[6]
Database references
SIMBADdata

HD 216770 is a star with an orbiting exoplanet in the southern constellation of Piscis Austrinus. With an apparent visual magnitude of 8.11,[2] it is too faint to be visible to the naked eye. It is located at a distance of 120 light years from the Sun, as determined by parallax measurements, and is drifting further away with a radial velocity of 31.1 km/s.[4] The star shows a high proper motion, traversing the celestial sphere at an angular rate of 0.302 arcsec yr−1.[7]

The spectrum of HD 216770 presents as a late G-type main-sequence star, a yellow dwarf, with a stellar classification of G9VCN+1,[3] where the suffix notation indicates anomalously strong band of CN. The star is smaller than the Sun, with 74% of the Sun's mass and 93% of the Sun's radius.[5] It is about three billion years old and is spinning slowly with a rotation period of 35.6 days.[2] The abundance of iron, a measure of the metallicity of the star, is higher than solar. The star is radiating 79% of the luminosity of the Sun from its photosphere at an effective temperature of 5,399 K.[5]

In 2003 an exoplanet was announced orbiting it by the Geneva Extrasolar Planet Search team.[2] As the inclination of the orbital plane is unknown, only a lower bound on the mass of the object can be determined. It has at least 65% of the mass of Jupiter. The body has an eccentric orbit with a period of 118.5 days.

The HD 216770 planetary system
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b >0.65 MJ 0.46 118.45 ± 0.55 0.37 ± 0.06 — —

See also

References

  1. 1 2 3 4 5 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.
  2. 1 2 3 4 5 6 7 8 9 10 11 Mayor, M.; et al. (2004). "The CORALIE survey for southern extra-solar planets XII. Orbital solutions for 16 extra-solar planets discovered with CORALIE". Astronomy and Astrophysics. 415 (1): 391–402. arXiv:astro-ph/0310316. Bibcode:2004A&A...415..391M. doi:10.1051/0004-6361:20034250. S2CID 5233877.
  3. 1 2 Gray, R. O.; et al. (July 2006). "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample". The Astronomical Journal. 132 (1): 161–170. arXiv:astro-ph/0603770. Bibcode:2006AJ....132..161G. doi:10.1086/504637. S2CID 119476992.
  4. 1 2 Soubiran, C.; et al. (2018). "Gaia Data Release 2. The catalogue of radial velocity standard stars". Astronomy and Astrophysics. 616: A7. arXiv:1804.09370. Bibcode:2018A&A...616A...7S. doi:10.1051/0004-6361/201832795. S2CID 52952408.
  5. 1 2 3 4 5 6 7 Stassun, Keivan G.; et al. (2017). "Accurate Empirical Radii and Masses of Planets and Their Host Stars with Gaia Parallaxes". The Astronomical Journal. 153 (3): 136. arXiv:1609.04389. Bibcode:2017AJ....153..136S. doi:10.3847/1538-3881/aa5df3. S2CID 119219062.
  6. ↑ "HD 216770". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-06-25.
  7. ↑ Luyten, W. J. (June 1995). "NLTT Catalogue (Luyten, 1979)". VizieR Online Data Catalog. Bibcode:1995yCat.1098....0L.
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