Astronomy:HD 118203
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Ursa Major[1] |
| Right ascension | 13h 34m 02.5394s[2] |
| Declination | +53° 43′ 42.698″[2] |
| Apparent magnitude (V) | 8.06[3] |
| Characteristics | |
| Evolutionary stage | subgiant[2][4] |
| Spectral type | G0V[5] |
| B−V color index | 0.699±0.012[1] |
| Astrometry | |
| Radial velocity (Rv) | −29.37±0.13[2] km/s |
| Proper motion (μ) | RA: −85.849(18)[2] mas/yr Dec.: −78.888(20)[2] mas/yr |
| Parallax (π) | 10.8643 ± 0.0180[2] mas |
| Distance | 300.2 ± 0.5 ly (92.0 ± 0.2 pc) |
| Absolute magnitude (MV) | 3.32[3] |
| Details[6] | |
| Mass | 1.353±0.006 M☉ |
| Radius | 1.993±0.065 R☉ |
| Luminosity | 4.42±0.02 L☉ |
| Surface gravity (log g) | 4.05±0.04 cgs |
| Temperature | 5,872±20 K |
| Metallicity [Fe/H] | 0.27±0.02 dex |
| Rotational velocity (v sin i) | 7.0[3] km/s |
| Age | 5.4±0.5[7] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | The star |
| planet b | |
| Exoplanet Archive | 118203 data |
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.[9][10]
The apparent visual magnitude of HD 118203 is 8.06,[3] 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 300 light years from the Sun.[2] The star is drifting closer with a radial velocity of −29 km/s.[1] Based on its position and space velocity this is most likely (97% chance) an older thin disk star.[11] An exoplanet has been detected in a close orbit around the star.[12]
The spectrum of HD 118203 matches a G-type main-sequence star with a class of G0V.[5] Despite that spectral classification, it appears to have evolved away from the main sequence to become a subgiant.[4] It has a low level of chromospheric activity, which means a low level of radial velocity jitter for planet detection purposes.[12] The star has 1.23[7] 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.[3] HD 118203 is radiating 3.8 times the luminosity of the Sun from its photosphere at an effective temperature of 5,741 K.[7]
Planetary system
In 2006, a hot Jupiter, HD 118203 b, 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.[12] 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 is 13% greater in radius. The fact that the parent star is among the brighter known planet hosts (as of 2020) makes it an interesting object for further study.[11] This planet received the proper name Staburags in the 2019 NameExoWorlds campaign.[9]
In 2024, the star HD 118203 was found to display variability with a period matching that of planet b's orbit, suggesting magnetic interaction between the star and planet.[6]
Also in 2024, a second massive planet was discovered using radial velocity observations as well as Hipparcos and Gaia astrometry. HD 118203 c is about 11 times the mass of Jupiter and takes 14 years to complete an orbit around the star. Like planet b, the orbit of planet c is close to edge-on, suggesting an aligned planetary system. The presence of any additional transiting planets at least twice the size of Earth and with periods less than 100 days was ruled out by the observations.[4]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b / Staburags | 2.182±0.033 MJ | 0.0701±0.0004 | 6.1349890(13) | 0.301±0.006 | 88.9+0.8 −1.0° |
1.12±0.09 RJ |
| c | 11.1+1.3 −1.0 MJ |
6.20±0.20 | 5070+240 −230 |
0.257±0.034 | 95+15 −19° |
— |
See also
- List of extrasolar planets
References
- ↑ 1.0 1.1 1.2 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 3.0 3.1 3.2 3.3 3.4 Luck, R. Earle (January 2017). "Abundances in the Local Region II: F, G, and K Dwarfs and Subgiants". The Astronomical Journal 153 (1): 19. doi:10.3847/1538-3881/153/1/21. 21. Bibcode: 2017AJ....153...21L.
- ↑ 4.0 4.1 4.2 4.3 Maciejewski, G. et al. (July 2024). "Tracking Advanced Planetary Systems (TAPAS) with HARPS-N VIII. A wide-orbit planetary companion in the hot-Jupiter system HD 118203". Astronomy & Astrophysics 688: A172. doi:10.1051/0004-6361/202451084. Bibcode: 2024A&A...688A.172M.
- ↑ 5.0 5.1 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. doi:10.1093/mnras/sty2431. Bibcode: 2018MNRAS.481.3244G.
- ↑ 6.0 6.1 Castro-González, A. et al. (April 2024). "Signs of magnetic star-planet interactions in HD 118203. TESS detects stellar variability that matches the orbital period of a close-in eccentric Jupiter-sized companion". Astronomy & Astrophysics 684: A160. doi:10.1051/0004-6361/202348722. Bibcode: 2024A&A...684A.160C.
- ↑ 7.0 7.1 7.2 Bonfanti, A. et al. (2015). "Age consistency between exoplanet hosts and field stars". Astronomy & Astrophysics 585: A5. doi:10.1051/0004-6361/201527297. Bibcode: 2016A&A...585A...5B.
- ↑ "HD 118203". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+118203.
- ↑ 9.0 9.1 "Approved names" (in en). http://www.nameexoworlds.iau.org/final-results.
- ↑ "International Astronomical Union | IAU". https://www.iau.org/news/pressreleases/detail/iau1912/.
- ↑ 11.0 11.1 Pepper, Joshua et al. (2020). "TESS Reveals HD 118203 b to be a Transiting Planet". The Astronomical Journal 159 (6): 243. doi:10.3847/1538-3881/ab84f2. Bibcode: 2020AJ....159..243P.
- ↑ 12.0 12.1 12.2 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. doi:10.1051/0004-6361:20054116. Bibcode: 2006A&A...446..717D.
Coordinates: 
13h 34m 02.5375s, +53° 43′ 42.704″
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