HD 203949

HD 203949
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] M_J	0.81±0.03	184.2±0.5	0.02±0.03	—	—

Planetary minimal mass must be revised down by 30% according to Campante et al.[2]

References

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.
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.
Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars". Michigan Spectral Survey. 5. Bibcode:1999MSS...C05....0H.
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.
"HD 121056". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-05-13.
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.
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.
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.

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[9] Planetary minimal mass must be revised down by 30% according to Campante et al.[2]

[EDR3-1] 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.

[Campante2019-2] 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.

[houk1999-3] Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars". Michigan Spectral Survey. 5. Bibcode:1999MSS...C05....0H.

[xhip-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.

[SIMBAD-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.

[Jones2014-7] 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.