HD 180902
| Observation data Epoch J2000.0 Equinox J2000.0 | ||
|---|---|---|
| Constellation | Sagittarius | |
| Right ascension | 19h 19m 17.708s[1] | |
| Declination | −23° 33′ 29.36″[1] | |
| Apparent magnitude (V) | 7.785[2] | |
| Characteristics | ||
| Spectral type | K0 III/IV[3] | |
| B−V color index | +0.94[4] | |
| Absolute magnitude (MV) | 2.5±0.3[4] | |
Semi-amplitude (K1)(primary) | 898±28 km/s | |
| Details | ||
| HD 180902 A | ||
Gyr | ||
| HD 180902 B | ||
| Mass | 44.53+12.91 −5.88[2] MJup | |
PPM 269620[6] | ||
| Database references | ||
| SIMBAD | data | |
HD 180902 is a
apparent visual magnitude of the system is 7.8,[2]
which is too faint to be seen with the naked eye.
The
subgiant star[5] with a stellar classification of K0 III/IV.[3] It is an estimated 2.8[4] billion years old with 1.7 times the mass of the Sun. The star has expanded to 4.2 times the radius of the Sun[2] and is radiating 9.4 times the Sun's luminosity from an enlarged photosphere at an effective temperature of 5,030 K.[4]
Companions
HD 180902 b was discovered using the Doppler spectroscopy method with observations taken at the W. M. Keck Observatory.[4] The radial velocities showed a long term linear trend in the data indicating an additional companion of unknown nature with a longer orbital period.[4] This was subsequently shown to be due to an orbiting brown dwarf or low mass stellar companion, designated component B.[5]
There is a second unconfirmed planet, HD 180902 c, with a mass at least twice that of Neptune and an orbital period of 15 days.[5]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | ≥1.685±0.041 MJ | 1.40±0.11 | 510.9±1.5 | 0.107±0.022 | — | — |
| c (unconfirmed) | ≥0.099±0.014 MJ | 0.139±0.011 | 15.9058±0.0055 | 0.28±0.13 | — | — |
References
- ^ S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ S2CID 119491061, A72.
- ^ Bibcode:1988mcts.book.....H.
- ^ doi:10.1086/653809.
- ^ S2CID 102486961.
- ^ "HD 180902". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-09-21.
