| Observation data EpochJ2000.0 EquinoxJ2000.0 (ICRS) | |
|---|---|
| Constellation | Cetus |
| Right ascension | 00h 21m 13.327s[1] |
| Declination | −08° 16′ 52.16″[1] |
| Apparent magnitude (V) | 9.19[2] |
| Characteristics | |
| Evolutionary stage | Giant |
| Spectral type | K1 III[3] |
| B−Vcolor index | 1.354±0.045[2] |
| Astrometry | |
| Radial velocity (Rv) | +18.216±0.011[4] km/s |
| Proper motion (μ) | RA: 13.285mas/yr[1] Dec.: 2.919mas/yr[1] |
| Parallax (π) | 1.2679±0.0273 mas[1] |
| Distance | 2,570 ± 60 ly (790 ± 20 pc) |
| Details | |
| Mass | 1.18±0.23[5] M☉ |
| Radius | 16.7[6] R☉ |
| Surface gravity (log g) | 2.12±0.17[5] cgs |
| Temperature | 4,393±85 K |
| Metallicity[Fe/H] | −0.32±0.06 dex |
| Rotational velocity (v sin i) | 1.86±0.07 km/s |
| Age | 6.7±3.2[7] Gyr |
| Other designations | |
| BD−09 54,Gaia DR2 2430036837596487424,HD 1690,HIP 1692,TYC 5262-825-1,2MASS J00211332-0816521[8] | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
HD 1690 is agiant star with an orbitingexoplanet companion in theconstellation ofCetus. It has anapparent visual magnitude of 9.19,[2] which is too faint to be visible to the naked eye. The distance to this system is approximately 2,570 light years, and it is drifting further away with aradial velocity of +18.2 km/s.[4] HD 1690 has no knowncompanion star, making it a single star system.[9]
This is anevolvedK-type giant star with astellar classification of K1 III.[3] It has 1.18 times the mass of the Sun and, at the estimated age of 6.7 billion years (two billion years older thanthe Sun), it has expanded to 16 times the Sun's radius. The surfacemetallicity of HD 1690 (the abundance of elements more massive than helium) is 30% that of the sun.[5] TheHipparcos parallax data have resulted in a distance determination of just1,012 light years,[10] but more recent data fromGaia data have placed HD 1690 much farther from the Sun at2,500 light years.[11]
In 2010, a team of astronomers led by astronomer C. Moutou of theHigh Accuracy Radial Velocity Planet Searcher performed a radial-velocity analysis that detected agas giant planet in orbit around HD 1690.[7]
The planetHD 1690 b has a very eccentric (far from circular) orbit; itsorbital eccentricity is 0.64. This eccentricity suggests that its mass is at least six times that ofJupiter, classifying it as asuper-Jupiter.[7] Other planets in the HD 1690 system are unlikely unless they are located on unstable crossing orbital paths.[9]
| Companion (in order from star) | Mass | Semimajor axis (AU) | Orbital period (days) | Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | >6.9±0.9 MJ | 1.3±0.02 | 533±1.7 | 0.64±0.04 | — | — |
