HD 181342

HD 181342 / Belel
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]
Distance394 ± 2 ly
(120.8 ± 0.7 pc)
Absolute magnitude (MV)2.2 ± 0.2[2]
Details[4]
Mass1.78 ± 0.11 M☉
Radius4.55 ± 0.49 R☉
Luminosity16.2 L☉
Surface gravity (log g)3.42 ± 0.07 cgs
Temperature4976 ± 26 K
Metallicity [Fe/H]+0.22 ± 0.05 dex
Rotational velocity (v sin i)1.92 ± 0.23 km/s
Age1.56 ± 0.28 Gyr
Other designations
CD−23° 15307, CPD−23° 7442, HD 181342, HIP 95124, SAO 188005[5]
Database references
SIMBADdata

HD 181342 is a star with an orbiting exoplanet 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] It is drifting closer with a heliocentric radial velocity of radial_v −0.8 km/s.[4]

The star HD 181342 is named Belel and the planetary companion is Dopere. 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. Dopere is an expansive historical area in the north of Senegal where Belel was located.[6][7]

HD 181342 is a K-type red giant star with a stellar classification of K0 III.[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 effective temperature is 4,976 K.[4]

A survey in 2015 ruled out the existence of any additional stellar companions at projected distances from 138 to 762 astronomical units.[8]

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]

The HD 181342 planetary system[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

  1. ^ a b c d e f 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.
  2. ^ a b c d e f 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.
  3. ^ a b 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.
  4. ^ a b c d e 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.
  5. ^ "HD 181342". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-09-19.
  6. ^ "Approved names". NameExoworlds. Retrieved 2020-01-02.
  7. ^ "International Astronomical Union | IAU". www.iau.org. Retrieved 2020-01-02.
  8. ^ 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. hdl:1887/49340. Retrieved 19 June 2020.
  9. ^ a b 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.