HD 203949
Star in the constellation Microscopium
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HD 203949 is a K-type giant star 257 light-years away in the constellation of Microscopium. Its surface temperature is 4618±113 K. It is either on the red giant branch fusing hydrogen in a shell around a helium core, or more likely a red clump star currently fusing helium in its core.[3] HD 203949 is enriched in heavy elements relative to the Sun, with a metallicity ([Fe/H]) of 0.17±0.07 dex. As is common for red giants, HD 203949 has an enhanced concentration of sodium and aluminium compared to iron.[3]
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Microscopium[1] |
| Right ascension | 21h 26m 22.8745s[2] |
| Declination | −37° 49′ 45.950″[2] |
| Apparent magnitude (V) | 5.62±0.01[3] |
| Characteristics | |
| Evolutionary stage | red giant branch or red clump[3] |
| Spectral type | K2III[4] |
| Astrometry | |
| Radial velocity (Rv) | −83.50±0.16[2] km/s |
| Proper motion (μ) | RA: 168.257[2] mas/yr Dec.: −11.075[2] mas/yr |
| Parallax (π) | 12.6806±0.0577 mas[2] |
| Distance | 257 ± 1 ly (78.9 ± 0.4 pc) |
| Absolute magnitude (MV) | +1.10[1] |
| Details[3] | |
| Mass | 1.00±0.16 M☉ |
| Radius | 10.30±0.51 R☉ |
| Luminosity (bolometric) | 43.34±4.27 L☉ |
| Surface gravity (log g) | 2.415±0.044 cgs |
| Temperature | 4618±113 K |
| Metallicity [Fe/H] | 0.17±0.07 dex |
| Age | 7.29±3.06 Gyr |
| Other designations | |
| CD−38 14551, HIP 105854, HR 8200, TYC 7979-47-1, GSC 07979-00047, 2MASS J21262286-3749458, Gaia DR2 6583094222249556224[5] | |
| Database references | |
| SIMBAD | data |
Multiplicity surveys did not find any stellar companions around HD 203949 as of 2019.[6]
Planetary system
In 2014, one planet orbiting HD 203949 was discovered by the radial velocity method.[7] The planet is highly unlikely to have survived the red giant stage of stellar evolution on the present orbit. It is likely to be recently scattered from a wider orbit.[3]
The planetary system configuration is favourable for direct imaging of exoplanets in the near future, and was included in the top ten easiest targets known by 2018.[8]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| HIP 105854b | >8.2±0.2[note 1] MJ | 0.81±0.03 | 184.2±0.5 | 0.02±0.03 | — | — |