HD 43197 is a star with an exoplanetary companion in the southern constellation of Canis Major. It has been given the proper name Amadioha, as selected by Nigeria during the NameExoWorlds campaign that celebrated the 100th anniversary of the IAU. Amadioha is the god of thunder in Igbo mythology.[7][8] It has an apparent visual magnitude of 8.98,[2] meaning this is a ninth magnitude star that is too dim to be visible to the naked eye. The system is located at a distance of 204 light-years from the Sun based on parallax measurements, and is drifting further away with a radial velocity of +72 km/s.[1] It made its closest approach some 583,000 years ago when it came to within 87 light-years.[2]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Canis Major |
| Right ascension | 06h 13m 35.66155s[1] |
| Declination | −29° 53′ 50.1516″[1] |
| Apparent magnitude (V) | 8.98[2] |
| Characteristics | |
| Spectral type | G8/K0 IV/V[3] |
| Apparent magnitude (B) | 9.797[2] |
| Apparent magnitude (J) | 7.658±0.024[2] |
| Apparent magnitude (H) | 7.328±0.038[2] |
| Apparent magnitude (K) | 7.203±0.026[2] |
| B−V color index | 0.817±0.022[2] |
| Astrometry | |
| Radial velocity (Rv) | 72.45±0.13[1] km/s |
| Proper motion (μ) | RA: 147.648±0.010 mas/yr[1] Dec.: 16.600±0.011 mas/yr[1] |
| Parallax (π) | 16.0171 ± 0.0106 mas[1] |
| Distance | 203.6 ± 0.1 ly (62.43 ± 0.04 pc) |
| Absolute magnitude (MV) | 5.24[2] |
| Details | |
| Mass | 1.02±0.02[4] M☉ |
| Radius | 0.96±0.02[4] R☉ |
| Luminosity | 0.74±0.01[4] L☉ |
| Surface gravity (log g) | 4.47±0.03[4] cgs |
| Temperature | 5,469±35[4] K |
| Metallicity [Fe/H] | 0.4[5] dex |
| Rotational velocity (v sin i) | 2.18[5] km/s |
| Age | 3.1±2.0[4] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
The stellar classification of this star is G8/K0 IV/V,[3] which may be interpreted to mean the spectrum is intermediate between similar stars of class G8 and K0, and its luminosity class showing a blend of a main sequence star (V) and a subgiant star (IV). It is a weakly active star with a high metallicity, being five halves as much as the Sun.[5] The star is about the same mass and size as the Sun, although the luminosity is only 74% of solar.[4] The star's age is estimated to be at least three billion years[5] and it is modelled to be right at the end of its main sequence life.[1]
Planetary system
editIn 2009, the HARPS planet search program announced a Jovian planet in a highly eccentric orbit around the star.[5] The planet spends ~78% of its orbital period in the habitable zone of the host star, although temperatures can reach 716 K during periastron passage.[9] In 2022, a second super-Jovian planet was discovered using a combination of radial velocity and astrometry. Assuming the inner planet shares the outer planet's orbital inclination, its true mass would be about 4 MJ.[10]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b (Equiano) | ≥0.553+0.052 −0.048 MJ |
0.882+0.035 −0.039 |
308.9+2.3 −2.8 |
0.742+0.017 −0.018 |
— | — |
| c | 7.868+1.760 −1.599 MJ |
8.540+2.334 −1.584 |
9296.0+4133.0 −2422.1 |
0.149+0.112 −0.087 |
11.420+5.388 −3.070° |
— |
See also
editReferences
edit- ^ a b c d e f g Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ a b c d e f g h i 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 Houk, Nancy (1982). Michigan catalogue of two-dimensional spectral types for the HD stars. Vol. 3. Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan. Bibcode:1982mcts.book.....H.
- ^ a b c d e f g Bonfanti, A.; et al. (2015). "Revising the ages of planet-hosting stars". Astronomy and Astrophysics. 575. A18. arXiv:1411.4302. Bibcode:2015A&A...575A..18B. doi:10.1051/0004-6361/201424951. S2CID 54555839.
- ^ a b c d e Naef, Dominique; et al. (2010). "The HARPS Search for Southern Extrasolar Planets XXIII. 8 Planetary Companions to Low-activity Solar-type Stars". Astronomy and Astrophysics. 523: A15. arXiv:1008.4600. Bibcode:2010A&A...523A..15N. doi:10.1051/0004-6361/200913616. S2CID 118845989.
- ^ "HD 43197". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-10-20.
- ^ "Approved names". NameExoworlds. IAU. Retrieved 2020-01-02.
- ^ "International Astronomical Union | IAU". www.iau.org. IAU. Retrieved 2020-01-02.
- ^ Kane, Stephen R.; Gelino, Dawn M. (November 2011). "Detectability of Exoplanet Periastron Passage in the Infrared". The Astrophysical Journal. 741 (1): 9. arXiv:1108.1803. Bibcode:2011ApJ...741...52K. doi:10.1088/0004-637X/741/1/52. S2CID 42643810. 52.
- ^ a b Feng, Fabo; Butler, R. Paul; et al. (August 2022). "3D Selection of 167 Substellar Companions to Nearby Stars". The Astrophysical Journal Supplement Series. 262 (21): 21. arXiv:2208.12720. Bibcode:2022ApJS..262...21F. doi:10.3847/1538-4365/ac7e57. S2CID 251864022.