HD 208487
Star in the constellation Grus From Wikipedia, the free encyclopedia
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]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Grus[1] |
| Right ascension | 21h 57m 19.84754s[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 | |
| Database references | |
| SIMBAD | data |
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]
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]
| 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 | — | — |
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