Summary
HD 118203 is a star with an orbiting exoplanet located in the northern circumpolar constellation of Ursa Major. It has the proper name Liesma, which means flame, and it is the name of a character from the Latvian poem Staburags un Liesma (Staburags and Liesma). The name was selected in the NameExoWorlds campaign by Latvia, during the 100th anniversary of the IAU.[7][8]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Ursa Major |
| Right ascension | 13h 34m 02.5394s[1] |
| Declination | +53° 43′ 42.6984″[1] |
| Apparent magnitude (V) | 8.06[2] |
| Characteristics | |
| Spectral type | G0V[3] |
| B−V color index | 0.699±0.012[4] |
| Astrometry | |
| Radial velocity (Rv) | −29.07±0.24[4] km/s |
| Proper motion (μ) | RA: −85.877±0.052[1] mas/yr Dec.: −78.913±0.038[1] mas/yr |
| Parallax (π) | 10.8102 ± 0.0275 mas[1] |
| Distance | 301.7 ± 0.8 ly (92.5 ± 0.2 pc) |
| Absolute magnitude (MV) | 3.32[2] |
| Details[5] | |
| Mass | 1.23±0.03 M☉ |
| Radius | 2.00±0.10 R☉ |
| Luminosity | 3.80±0.30 L☉ |
| Surface gravity (log g) | 3.93±0.02 cgs |
| Temperature | 5,741±35 K |
| Metallicity [Fe/H] | 0.16[2] dex |
| Rotational velocity (v sin i) | 7.0[2] km/s |
| Age | 5.4±0.5 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | The star |
| planet b | |
| Exoplanet Archive | data |
The apparent visual magnitude of HD 118203 is 8.06,[2] which means it is invisible to the naked eye but it can be seen using binoculars or a telescope. Based on parallax measurements, it is located at a distance of 302 light years from the Sun.[1] The star is drifting closer with a radial velocity of −29 km/s.[4] Based on its position and space velocity this is most likely (97% chance) an older thin disk star.[9] An exoplanet has been detected in a close orbit around the star.[10]
The spectrum of HD 118203 matches a G-type main-sequence star with a class of G0V.[3] It has a low level of chromospheric activity, which means a low level of radial velocity jitter for planet detection purposes.[10] The star has 1.23[5] times the mass of the Sun and double the Sun's radius. It is around 5.4 billion years old and is spinning with a projected rotational velocity of 7.0 km/s.[2] HD 118203 is radiating 3.8 times the luminosity of the Sun from its photosphere at an effective temperature of 5,741 K.[5]
Exoplanet edit
In 2006, a hot Jupiter candidate was reported in an eccentric orbit around this star. It was discovered using the radial velocity method based on observation of high-metallicity stars begun in 2004.[10] In 2020, it was found that this is a transiting planet, which allowed the mass and radius of the body to be determined. This exoplanet has more than double the mass of Jupiter and a 13% greater radius. It is named Staburags. The fact that the parent star is among the brighter known planet hosts (as of 2020) makes it an interesting object for further study.[9]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b / Staburags | 2.173+0.077 −0.080 MJ |
0.07082+0.00095 −0.00110 |
6.134980+0.000038 −0.000037 |
0.316±0.021 | 88.75+0.86 −1.0° |
1.133+0.031 −0.030 RJ |
See also edit
References edit
- ^ 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.
- ^ a b c d e f Luck, R. Earle (January 2017). "Abundances in the Local Region II: F, G, and K Dwarfs and Subgiants". The Astronomical Journal. 153 (1): 19. arXiv:1611.02897. Bibcode:2017AJ....153...21L. doi:10.3847/1538-3881/153/1/21. S2CID 119511744. 21.
- ^ a b Grieves, N.; et al. (December 2018). "Chemo-kinematics of the Milky Way from the SDSS-III MARVELS survey". Monthly Notices of the Royal Astronomical Society. 481 (3): 3244–3265. arXiv:1803.11538. Bibcode:2018MNRAS.481.3244G. doi:10.1093/mnras/sty2431.
- ^ a b c Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644.
- ^ a b c Bonfanti, A.; et al. (2015). "Age consistency between exoplanet hosts and field stars". Astronomy & Astrophysics. 585: A5. arXiv:1511.01744. Bibcode:2016A&A...585A...5B. doi:10.1051/0004-6361/201527297. S2CID 53971692.
- ^ "HD 118203". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-10-13.
- ^ "Approved names". NameExoworlds. Retrieved 2020-01-02.
- ^ "International Astronomical Union | IAU". www.iau.org. Retrieved 2020-01-02.
- ^ a b c Pepper, Joshua; et al. (2020). "TESS Reveals HD 118203 b to be a Transiting Planet". The Astronomical Journal. 159 (6): 243. arXiv:1911.05150. Bibcode:2020AJ....159..243P. doi:10.3847/1538-3881/ab84f2. S2CID 207930540.
- ^ a b c da Silva, R.; et al. (2006). "Elodie metallicity-biased search for transiting Hot Jupiters I. Two Hot Jupiters orbiting the slightly evolved stars HD118203 and HD149143". Astronomy and Astrophysics. 446 (2): 717–722. arXiv:astro-ph/0510048. Bibcode:2006A&A...446..717D. doi:10.1051/0004-6361:20054116. S2CID 18907493.