HD 203949

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HD 203949
Microscopium constellation map.svg
Red circle.svg
Location of HD 203949 on the map (circled)
Observation data
Epoch J2000       Equinox J2000
Constellation Microscopium
Right ascension 21h 26m 22.8745s [1]
Declination −37° 49 45.950 [1]
Apparent magnitude  (V)5.62±0.01 [2]
Characteristics
Evolutionary stage giant
Spectral type K2III [3]
Astrometry
Radial velocity (Rv)−83.50±0.16 [1]  km/s
Proper motion (μ)RA: 168.257 [1]   mas/yr
Dec.: −11.075 [1]   mas/yr
Parallax (π)12.6806 ± 0.0577  mas [1]
Distance 257 ± 1  ly
(78.9 ± 0.4  pc)
Absolute magnitude  (MV)+1.10 [4]
Details [2]
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, Gaia DR2  6583094222249556224, HIP  105854, HR  8200, TYC  7979-47-1, GSC  07979-00047, 2MASS J21262286-3749458 [5]
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. [2] 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. [2]

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. [2]

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]

The HD 203949 planetary system [7]
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±0.03184.2±0.50.02±0.03
  1. Planetary minimal mass must be revised down by 30% according to Campante et al. [2]

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References

  1. 1 2 3 4 5 6 Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics . 649: A1. arXiv: 2012.01533 . Bibcode:2021A&A...649A...1G. doi: 10.1051/0004-6361/202039657 . S2CID   227254300. (Erratum:  doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  2. 1 2 3 4 5 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. arXiv: 1909.05961 . Bibcode:2019ApJ...885...31C. doi: 10.3847/1538-4357/ab44a8 . S2CID   202572968.
  3. Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars". Michigan Spectral Survey. 5. Bibcode:1999MSS...C05....0H.
  4. 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.
  5. "HD 121056". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2021-05-13.
  6. 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. arXiv: 1903.02332 . doi: 10.1093/mnras/stz671 .
  7. 1 2 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. arXiv: 1406.0884 . Bibcode:2014A&A...566A.113J. doi:10.1051/0004-6361/201323345. S2CID   118396750.
  8. Martinache, Frantz; Ireland, Michael J. (2018). "Kernel-nulling for a robust direct interferometric detection of extrasolar planets". Astronomy & Astrophysics. 619: A87. arXiv: 1802.06252 . Bibcode:2018A&A...619A..87M. doi:10.1051/0004-6361/201832847. S2CID   118882482.