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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]
Planetary system
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 | — | — |
References
- Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
- Høg, E.; et al. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H.
- Houk, N.; Smith-Moore, M. (1988). "Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. Volume 4, Declinations -26°.0 to -12°.0". Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. 4. Bibcode:1988mcts.book.....H.
- Johnson, John Asher; et al. (2010). "Retired a Stars and Their Companions. IV. Seven Jovian Exoplanets from Keck Observatory". Publications of the Astronomical Society of the Pacific. 122 (892): 701–711. arXiv:1003.3445. Bibcode:2010PASP..122..701J. doi:10.1086/653809.
- Luhn, Jacob K.; et al. (2019). "Retired A Stars and Their Companions. VIII. 15 New Planetary Signals around Subgiants and Transit Parameters for California Planet Search Planets with Subgiant Hosts". The Astronomical Journal. 157 (4). 149. arXiv:1811.03043. Bibcode:2019AJ....157..149L. doi:10.3847/1538-3881/aaf5d0. S2CID 102486961.
- "HD 180902". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-09-21.
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HD 180902 — звезда в созвездии Стрельца на расстоянии около 359 световых лет от нас. Вокруг звезды обращается, как минимум, одна планета.Другой контент может иметь иную лицензию. Перед использованием материалов сайта WikiSort.org внимательно изучите правила лицензирования конкретных элементов наполнения сайта.
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