HD 181342
HD 181342 is a star in the constellation of Sagittarius. With an apparent magnitude of 7.55,[2] it cannot be seen with the naked eye. Parallax measurements made by Gaia spacecraft put the star at a distance of 394 light-years (121 parsecs) away.[1]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Sagittarius |
| Right ascension | 19h 21m 04.2304s[1] |
| Declination | −23° 37′ 10.4513″[1] |
| Apparent magnitude (V) | 7.55[2] |
| Characteristics | |
| Spectral type | K0 III[3] |
| B−V color index | +1.02[2] |
| Astrometry | |
| Radial velocity (Rv) | −0.76 ± 0.07[4] km/s |
| Proper motion (μ) | RA: −46.597±0.088[1] mas/yr Dec.: −30.158±0.074[1] mas/yr |
| Parallax (π) | 8.2778 ± 0.0475 mas[1] |
| Distance | 394 ± 2 ly (120.8 ± 0.7 pc) |
| Absolute magnitude (MV) | 2.2 ± 0.2[2] |
| Details[4] | |
| Mass | 1.78 ± 0.11 M☉ |
| Radius | 4.55 ± 0.49 R☉ |
| Luminosity | 16.2 L☉ |
| Surface gravity (log g) | 3.42 ± 0.07 cgs |
| Temperature | 4976 ± 26 K |
| Metallicity [Fe/H] | +0.22 ± 0.05 dex |
| Rotational velocity (v sin i) | 1.92 ± 0.23 km/s |
| Age | 1.56 ± 0.28 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
The survey in 2015 have ruled out the existence of any additional stellar companions at projected distances from 138 to 762 astronomical units.[6]
Nomenclature
The star HD 181342 is named Belel. The name was selected in the NameExoWorlds campaign by Senegal, during the 100th anniversary of the IAU. Belel is a rare source of water in the north of Senegal.[7][8]
Properties
HD 181342 is a K-type red giant star.[3] It was formerly an A-type main-sequence star,[2] but at an age of 1.56 billion years it has swelled up to a size of 4.55 solar radii.[4] It is currently 1.78 times the mass of the Sun, 16.2 times as luminous, and its surface temperature is 4976 K.[4]
Planetary system
HD 181342 is known to have one planet, detected with Doppler spectroscopy.[2] The planet, HD 181342 b, orbits at a distance of 1.59 astronomical units (au), every 564 days (almost 2 years). Its mass is at least two and a half times that of Jupiter.[9]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b / Dopere | ≥2.54±0.19 MJ | 1.592±0.091 | 564.1±4.1 | 0.022±0.051 | — | — |
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.
- 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.
- 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.
- Jofré, E.; Petrucci, R.; Saffe, C.; Saker, L.; de la Villarmois, E. Artur; Chavero, C.; Gómez, M.; Mauas, P. J. D. (2015). "Stellar parameters and chemical abundances of 223 evolved stars with and without planets". Astronomy & Astrophysics. 574: A50. arXiv:1410.6422. Bibcode:2015A&A...574A..50J. doi:10.1051/0004-6361/201424474. S2CID 53666931.
- "HD 181342". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-09-19.
- Mugrauer, M.; Ginski, C. (12 May 2015). "High-contrast imaging search for stellar and substellar companions of exoplanet host stars". Monthly Notices of the Royal Astronomical Society. 450 (3): 3127–3136. Bibcode:2015MNRAS.450.3127M. doi:10.1093/mnras/stv771. Retrieved 19 June 2020.
- "Approved names". NameExoworlds. Retrieved 2020-01-02.
- "International Astronomical Union | IAU". www.iau.org. Retrieved 2020-01-02.
- 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.