Astronomy:HD 203949
Coordinates: 
21h 26m 22.8745s, −37° 49′ 45.9539″
  | |
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| 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[2] mas |
| 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 | |
| Database references | |
| SIMBAD | data |
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]
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 | — | — |
References
- ↑ 1.0 1.1 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A XHIP record for this object at VizieR.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 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 3.5 3.6 Campante, Tiago L. et al. (2019). "TESS Asteroseismology of the Known Red-giant Host Stars HD 212771 and HD 203949". The Astrophysical Journal 885 (1): 31. doi:10.3847/1538-4357/ab44a8. Bibcode: 2019ApJ...885...31C.
- ↑ Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars". Michigan Spectral Survey 5. Bibcode: 1999MSS...C05....0H.
- ↑ "HD 121056". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+121056.
- ↑ Biller, B.; Mužić, K.; Lopez, E.; Bonavita, M.; Rice, K.; Fontanive, C. (2019). "A high binary fraction for the most massive close-in giant planets and brown dwarf desert members". Monthly Notices of the Royal Astronomical Society 485 (4): 4967–4996. doi:10.1093/mnras/stz671.
- ↑ 7.0 7.1 Jones, M. I.; Jenkins, J. S.; Bluhm, P.; Rojo, P.; Melo, C. H. F. (2014). "The properties of planets around giant stars". Astronomy & Astrophysics 566: A113. doi:10.1051/0004-6361/201323345. Bibcode: 2014A&A...566A.113J.
- ↑ Martinache, Frantz; Ireland, Michael J. (2018). "Kernel-nulling for a robust direct interferometric detection of extrasolar planets". Astronomy & Astrophysics 619: A87. doi:10.1051/0004-6361/201832847. Bibcode: 2018A&A...619A..87M.
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