HD 22781

HD 22781, is a single star about 106 light-years away. It is a K-type main-sequence star. The star’s age is poorly constrained at 4.14±3.63 billion years, but is likely similar to that of the Sun.[5] HD 22781 is heavily depleted in heavy elements, having just 45% of Sun's concentration of iron,[2] yet is comparatively rich in carbon, having 90% of Sun`s abundance.[5]

HD 22781
Observation data
Epoch J2000      Equinox J2000
Constellation Perseus
Right ascension 03h 40m 49.5246s[1]
Declination +31° 49′ 34.6489″[1]
Apparent magnitude (V) 8.78[2]
Characteristics
Evolutionary stage main-sequence star[3]
Spectral type K0[2]
Astrometry
Radial velocity (Rv)8.26[1] km/s
Proper motion (μ) RA: 40.576[1] mas/yr
Dec.: −94.254[1] mas/yr
Parallax (π)30.6433 ± 0.1071[4] mas
Distance106.4 ± 0.4 ly
(32.6 ± 0.1 pc)
Details[5]
Mass0.75±0.02 M☉
Radius0.70±0.02 R☉
Surface gravity (log g)4.57±0.04 cgs
Temperature5175±15 K
Metallicity [Fe/H]−0.35±0.02 dex
Rotational velocity (v sin i)1.73[3] km/s
Age4.14±3.63 Gyr
Other designations
BD+31 630, Gaia DR2 217334764042444288, HD 22781, HIP 17187, TYC 2355-246-1, GSC 02355-00246, 2MASS J03404953+3149345[1]
Database references
SIMBADdata

An imaging survey in 2012 has failed to find any stellar companions, suggesting HD 22781 is a single star.[6]

Planetary system

In 2011 a transiting superjovian planet or brown dwarf b was detected on an extremely eccentric orbit.[3] It is located just outside of the conservative habitable zone of the parent star.[7] Planets around such metal-poor stars are rare; the only three known similar cases are HD 111232, HD 114762, and HD 181720.[8]

In 2012, a radial velocity data review indicated there are no additional giant planets in the system.[9]

The HD 22781 planetary system[3]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b ≥13.65±0.97 MJ 1.167±0.039 528.07±0.14 0.8191±0.0023 — —

References
  1. "HD 22781". SIMBAD. Centre de données astronomiques de Strasbourg.
  2. Maldonado, J.; Villaver, E.; Eiroa, C.; Micela, G. (2019), "Connecting substellar and stellar formation. The role of the host star's metallicity", Astronomy & Astrophysics, 624: A94, arXiv:1903.01141, Bibcode:2019A&A...624A..94M, doi:10.1051/0004-6361/201833827, S2CID 118934484
  3. Díaz, R. F.; Santerne, A.; Sahlmann, J.; Hébrard, G.; Eggenberger, A.; Santos, N. C.; Moutou, C.; Arnold, L.; Boisse, I.; Bonfils, X.; Bouchy, F.; Delfosse, X.; Desort, M.; Ehrenreich, D.; Forveille, T.; Lagrange, A. M.; Lovis, C.; Pepe, F.; Perrier, C.; Queloz, D.; Ségransan, D.; Udry, S.; Vidal-Madjar, A. (2012), "The SOPHIE search for northern extrasolar planets IV. Massive companions in the planet-brown dwarf boundary", Astronomy & Astrophysics, A113: 538, arXiv:1111.1168, Bibcode:2012A&A...538A.113D, doi:10.1051/0004-6361/201117935, S2CID 55322205
  4. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  5. Maldonado, J.; Villaver, E. (2017), "Searching for chemical signatures of brown dwarf formation", Astronomy & Astrophysics, 602: A38, arXiv:1702.02904, Bibcode:2017A&A...602A..38M, doi:10.1051/0004-6361/201630120, S2CID 56225222
  6. Ginski, C.; Mugrauer, M.; Seeliger, M.; Eisenbeiss, T. (2012), "A lucky imaging multiplicity study of exoplanet host stars", Monthly Notices of the Royal Astronomical Society, 421 (3): 2498–2509, arXiv:1202.4586, Bibcode:2012MNRAS.421.2498G, doi:10.1111/j.1365-2966.2012.20485.x, S2CID 118573795
  7. Agnew, Matthew T.; Maddison, Sarah T.; Thilliez, Elodie; Horner, Jonathan (2017), "Stable habitable zones of single Jovian planet systems", Monthly Notices of the Royal Astronomical Society, 471 (4): 4494–4507, arXiv:1706.05805, Bibcode:2017MNRAS.471.4494A, doi:10.1093/mnras/stx1449, S2CID 119227856
  8. Adibekyan, Vardan (2019), "Heavy Metal Rules. I. Exoplanet Incidence and Metallicity", Geosciences, 9 (3): 105, arXiv:1902.04493, Bibcode:2019Geosc...9..105A, doi:10.3390/geosciences9030105, S2CID 119089419
  9. Wittenmyer, Robert A.; Wang, Songhu; Horner, Jonathan; Tinney, C. G.; Butler, R. P.; Jones, H. R. A.; O'Toole, S. J.; Bailey, J.; Carter, B. D.; Salter, G. S.; Wright, D.; Zhou, Ji-Lin (2013), "Forever alone? Testing single eccentric planetary systems for multiple companions", The Astrophysical Journal Supplement Series, 208 (1): 2, arXiv:1307.0894, Bibcode:2013ApJS..208....2W, doi:10.1088/0067-0049/208/1/2, S2CID 14109907

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