HD 22781

Short description: Star in the constellation Perseus

HD 22781  Observation data
Equinox J2000.0]] (ICRS)

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
Distance| 106.4 ± 0.4 ly
(32.6 ± 0.1 pc)
Details[5]
Mass| 0.75±0.02 M☉
Radius| 0.70±0.02 R☉
Surface gravity (log g)| 4.57±0.04 cgs
Temperature| 5175±15 K
Metallicity [Fe/H]| −0.35±0.02 dex
Rotational velocity (v sin i)| 1.73[3] km/s
Age| 4.14±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
SIMBAD| data

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]

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 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. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 "HD 22781". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+22781.
2. ↑ 2.0 2.1 2.2 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, doi:10.1051/0004-6361/201833827, Bibcode: 2019A&A...624A..94M
3. ↑ 3.0 3.1 3.2 3.3 Díaz, Rodrigo F.; Santerne, Alexandre; Sahlmann, Johannes; Hébrard, Guillaume; Eggenberger, Anne; Santos, Nuno C.; Moutou, Claire; Arnold, Luc et al. (2012), "The SOPHIE search for northern extrasolar planets IV. Massive companions in the planet-brown dwarf boundary", Astronomy & Astrophysics A113: 538, doi:10.1051/0004-6361/201117935, Bibcode: 2012A&A...538A.113D
4. ↑ Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G. Gaia DR2 record for this source at VizieR.
5. ↑ 5.0 5.1 5.2 Maldonado, J.; Villaver, E. (2017), "Searching for chemical signatures of brown dwarf formation", Astronomy & Astrophysics 602: A38, doi:10.1051/0004-6361/201630120, Bibcode: 2017A&A...602A..38M
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, doi:10.1111/j.1365-2966.2012.20485.x, Bibcode: 2012MNRAS.421.2498G
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, doi:10.1093/mnras/stx1449, Bibcode: 2017MNRAS.471.4494A
8. ↑ Adibekyan, Vardan (2019), "Heavy Metal Rules. I. Exoplanet Incidence and Metallicity", Geosciences 9 (3): 105, doi:10.3390/geosciences9030105, Bibcode: 2019Geosc...9..105A
9. ↑ Wittenmyer, Robert A.; Wang, Songhu; Horner, Jonathan; Tinney, C. G.; Butler, R. P.; Jones, H. R. A.; O'Toole, S. J.; Bailey, J. et al. (2013), "Forever alone? Testing single eccentric planetary systems for multiple companions", The Astrophysical Journal Supplement Series 208 (1): 2, doi:10.1088/0067-0049/208/1/2, Bibcode: 2013ApJS..208....2W

Coordinates:  03h 40m 49.5246s, +31° 49′ 34.6489″

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*[RA:]: Right Ascension
*[Dec.:]: Declination