HD 180902 is a binary star approximately 342 light years away in the constellation Sagittarius. The primary is a K-type star while the nature of the secondary is unknown since it has only been detected by its effect on the radial velocity of the primary.[5][1]
Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Sagittarius |
Right ascension | 19h 19m 17.7078s[1] |
Declination | −23° 33′ 29.3632″[1] |
Apparent magnitude (V) | 7.78[2] |
Characteristics | |
Spectral type | K0 III/IV[3] |
B−V color index | +0.94[4] |
Astrometry | |
Proper motion (μ) | RA: 37.839±0.097[1] mas/yr Dec.: −20.148±0.079[1] mas/yr |
Parallax (π) | 9.5339 ± 0.0521 mas[1] |
Distance | 342 ± 2 ly (104.9 ± 0.6 pc) |
Absolute magnitude (MV) | 2.5 ± 0.3[4] |
Orbit[5] | |
Primary | HD 180902 A |
Companion | HD 180902 B |
Period (P) | 5880±440 d |
Semi-major axis (a) | 7.15±0.69 AU |
Eccentricity (e) | 0.335±0.025 |
Periastron epoch (T) | 2441100±1200 JD |
Argument of periastron (ω) (secondary) | 73.3±1.6° |
Semi-amplitude (K1) (primary) | 898±28 km/s |
Details[4] | |
Mass | 1.52 ± 0.11 M☉ |
Radius | 4.1 ± 0.1 R☉ |
Luminosity | 9.4 ± 0.5 L☉ |
Temperature | 5030 ± 44 K |
Metallicity [Fe/H] | 0.04 ± 0.03 dex |
Age | 2.8 ± 0.7 Gyr years |
Other designations | |
Database references | |
SIMBAD | data |
It has one confirmed planet, HD 180902 b,[4] and one candidate planet.[5]
HD 180902 b was discovered using the Doppler spectroscopy method with observations taken at the W. M. Keck Observatory.[4] The radial velocities showed there a long term linear trend in the data indicating an additional companion of unknown nature with a longer period.[4] This was later shown due to a stellar binary companion.[5]
There is second unconfirmed planet with a mass 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 (candidate) | ≥0.099±0.014 MJ | 0.139±0.011 | 15.9058±0.0055 | 0.28±0.13 | — | — |
Constellation of Sagittarius | |
---|---|
Bayer | |
Flamsteed | |
Variable |
|
HR |
|
HD | |
Gliese |
|
MOA | |
OGLE | |
PSR |
|
WR | |
Other |
|
Exoplanets |
|