HD 208487

HD 208487 / Itonda

Observation data Epoch J2000      Equinox J2000
Constellation	Grus[1]
Right ascension	21^h 57^m 19.84754^s[2]
Declination	−37° 45′ 49.0480″[2]
Apparent magnitude (V)	7.47[1]
Characteristics
Evolutionary stage	main sequence
Spectral type	G1/3V[3]
B−V color index	0.568±0.009[1]
Variable type	Stable[4]
Astrometry
Radial velocity (Rv)	5.575±0.0004[5] km/s
Proper motion (μ)	RA: 101.032 mas/yr[2] Dec.: −118.842 mas/yr[2]
Parallax (π)	22.2688 ± 0.0304 mas[2]
Distance	146.5 ± 0.2 ly (44.91 ± 0.06 pc)
Absolute magnitude (MV)	4.26[4]
Absolute bolometric magnitude (Mbol)	4.06[4]
Details
Mass	1.16±0.02[6] M☉
Radius	1.17±0.03[6] R☉
Luminosity	1.76±0.05[6] L☉
Surface gravity (log g)	4.36±0.03[6] cgs
Temperature	6,143±47[6] K
Metallicity [Fe/H]	0.08[7] dex
Rotational velocity (v sin i)	3.688[6] km/s
Age	2.3±0.9 Gyr[6] 1.325±1.007[7] Gyr
Other designations
Itonda, CD−38° 14804, HD 208487, HIP 108375, SAO 213432, PPM 302029[8]
Database references
SIMBAD	data

HD 208487 is a star with an orbiting exoplanet in the constellation of Grus. Based on parallax measurements, it is located at a distance of 146.5 light years from the Sun. The absolute magnitude of HD 208487 is 4.26,[4] but at that distance the apparent visual magnitude is 7.47,[1] which is too faint to be viewed with the naked eye. The system is drifting further away with a radial velocity of 5.6 km/s.[5] It is a member of the thin disk population.[7]

The spectrum of HD 208487 presents as an ordinary G-type main-sequence star with a stellar classification of G1/3V.[3] It is a relatively young star, with age estimates of 1–2 billion years, and is spinning with a projected rotational velocity of 3.7 km/s.[7][6] The star has 16% greater mass and a 17% larger radius than the Sun.[6] The abundance of iron, a measure of the star's metallicity, is similar to the Sun.[7] It is radiating 176% of the luminosity of the Sun from its photosphere at an effective temperature of 6,143 K.[6] The level of magnetic activity in the chromosphere is low.[4]

The star HD 208487 is named Itonda and the exoplanet Mintome. The names were selected in the NameExoWorlds campaign by Gabon, during the 100th anniversary of the IAU. Itonda, in the Myene tongue, corresponds to all that is beautiful. Mintome, in the Fang tongue, is a mythical land where a brotherhood of brave men live.[9][10]

Planetary system

There is one known planet orbiting the star HD 208487, which is designated HD 208487 b.[4] It has a mass at least half that of Jupiter and is located in an eccentric 130-day orbit.

The discovery of a second planet in the system was announced on 13 September 2005, by P.C. Gregory. The discovery was made using Bayesian analysis of the radial velocity dataset to determine the planetary parameters.[11] However, further analysis revealed that an alternative two-planet solution for the HD 208487 system was possible, with a planet in a 28-day orbit instead of the 908-day orbit postulated, and it was concluded that activity on the star is more likely to be responsible for the residuals to the one-planet solution than the presence of a second planet.[12]

The HD 208487 planetary system

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b / Mintome	>0.520 ± 0.082 MJ	0.51 ± 0.02	130.08 ± 0.51	0.24 ± 0.16	—	—

See also

• Lists of exoplanets

References

1. 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.
2. 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.
3. 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.
4. Tinney, C. G.; et al. (2005). "Three Low-Mass Planets from the Anglo-Australian Planet Search". The Astrophysical Journal. 623 (2): 1171–1179. Bibcode:2005ApJ...623.1171T. CiteSeerX 10.1.1.491.2941. doi:10.1086/428661. S2CID 12515735.
5. Soubiran, C.; et al. (2018). "Gaia Data Release 2. The catalogue of radial velocity standard stars". Astronomy and Astrophysics. 616: A7. arXiv:1804.09370. Bibcode:2018A&A...616A...7S. doi:10.1051/0004-6361/201832795. S2CID 52952408.
6. Bonfanti, A.; et al. (2016). "Age consistency between exoplanet hosts and field stars". Astronomy & Astrophysics. 585: 14. arXiv:1511.01744. Bibcode:2016A&A...585A...5B. doi:10.1051/0004-6361/201527297. S2CID 53971692. A5.
7. Costa Silva, A. R.; et al. (February 2020). "Chemical abundances of 1111 FGK stars from the HARPS-GTO planet search sample. III. Sulfur". Astronomy & Astrophysics. 634: 10. arXiv:1912.08659. Bibcode:2020A&A...634A.136C. doi:10.1051/0004-6361/201936523. S2CID 209405391. A136.
8. "HD 208487". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-05-06.
9. "Approved names". NameExoworlds. Retrieved 2020-01-02.
10. "International Astronomical Union | IAU". www.iau.org. Retrieved 2020-01-02.
11. Gregory, P.C. (2007). "A Bayesian Kepler periodogram detects a second planet in HD 208487". Monthly Notices of the Royal Astronomical Society. 374 (4): 1321–1333. arXiv:astro-ph/0609229. Bibcode:2007MNRAS.374.1321G. doi:10.1111/j.1365-2966.2006.11240.x. S2CID 8220838.
12. Wright, J.T.; et al. (2007). "Four New Exoplanets and Hints of Additional Substellar Companions to Exoplanet Host Stars". The Astrophysical Journal. 657 (1): 533–545. arXiv:astro-ph/0611658. Bibcode:2007ApJ...657..533W. doi:10.1086/510553. S2CID 35682784.

External links

• "Notes for star HD 208487". Extrasolar Planets Encyclopaedia. Archived from the original on June 20, 2006. Retrieved 2008-08-29.