Global InformationHD 216770 information
| 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] |
| Distance | 119.5 ± 0.1 ly (36.64 ± 0.03 pc) |
| Absolute magnitude (MV) | 5.22[2] |
| Details | |
| Mass | 0.74±0.07[5] M☉ |
| Radius | 0.93±0.02[5] R☉ |
| Luminosity | 0.79[2] L☉ |
| Surface gravity (log g) | 4.37±0.04[5] cgs |
| Temperature | 5,399±18[5] K |
| Metallicity [Fe/H] | 0.27[5] dex |
| Rotation | 35.6 d[2] |
| Rotational velocity (v sin i) | 1.4[2] km/s |
| Age | 3.1[2] Gyr |
| Other designations | |
CD−27°16109, GC 31973, HIP 113238, SAO 191502, LTT 9276, NLTT 55283[6] | |
| Database references | |
| SIMBAD | data |
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.
| 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 | — | — |
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