HD 233731
HD 233731, or HAT-P-22, is a suspected multiple star system in the northern circumpolar constellation of Ursa Major. It is invisible to the naked eye, having an apparent visual magnitude of 9.732.[2] This system is located at a distance of 267 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +13 km/s.[1]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Ursa Major |
| Right ascension | 10h 22m 43.59244s[1] |
| Declination | +50° 07′ 42.0635″[1] |
| Apparent magnitude (V) | 9.732[2] |
| Characteristics | |
| Spectral type | G5V[3] |
| B−V color index | 0.86[3] |
| Astrometry | |
| Radial velocity (Rv) | 12.63±0.26[1] km/s |
| Proper motion (μ) | RA: −26.182[1] mas/yr Dec.: 83.727[1] mas/yr |
| Parallax (π) | 12.2014 ± 0.0371[1] mas |
| Distance | 267.3 ± 0.8 ly (82.0 ± 0.2 pc) |
| Absolute magnitude (MV) | 5.22±0.14[2] |
| Details[3] | |
| Mass | 0.936+0.028 −0.033 M☉ |
| Radius | 1.062+0.046 −0.013 R☉ |
| Luminosity | 0.77±0.09[2] L☉ |
| Surface gravity (log g) | 4.357+0.039 −0.005 cgs |
| Temperature | 5,314±50 K |
| Metallicity [Fe/H] | 0.30±0.09 dex |
| Rotation | 28.7±0.4 d |
| Rotational velocity (v sin i) | 1.65±0.26 km/s |
| Age | 9.0+1.4 −2.2 Gyr[3] 12.4±2.6[2] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
The stellar classification of the primary is G5V,[3] matching an ordinary G-type main-sequence star. The star has a low level of stellar activity with an estimated age of 9 to 12 billion years old. Its metallicity is twice that of the Sun, unusual for its advanced age.[3] HD 233731 has a similar mass and radius as the Sun, and is spinning with a rotation period of 28.7 days.[3] It is radiating 77%[2] of the luminosity of the Sun from its photosphere at an effective temperature of 5314 K.[3]
A faint stellar companion (2MASS J10224397+5007504) with a red hue is located at an angular separation of 9 arcseconds from the primary.[2] In 2015, a spectroscopic stellar companion was reported with a semimajor axis of less than 33 AU. This star has an effective temperature of 4,000+250
−400 K with a mass of 0.63+0.07
−0.17 M☉.[5]
Planetary system
In 2010 a transiting hot Jupiter like planet was detected, designated HAT-P-22b.[2] It has an equilibrium temperature of 1,463±19 K, and planetary atmosphere is cloudy.[6] The measurement of Rossiter-McLaughlin effect in 2018 has allowed to detect what the planetary orbit is well aligned with the equatorial plane of the star, with a misalignment angle equal to 25°±18°.[3]
In 2017, analysis of additional HARPS data showed a long-term trend that suggested the presence of an additional orbiting companion, HAT-P-22c.[7]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 2.192+0.073 −0.013 MJ |
0.04171+0.00042 −0.00050 |
3.21223328 | 0.016±0.009 | 86.46±0.41° | 1.060±0.048 RJ |
| c (unconfirmed) | ≥3.0 MJ | — | ≥20.8 years | — | — | — |
References
- 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.
- Bakos, G. Á.; et al. (2010), "HAT-P-20b – HAT-P-23b: Four Massive Transiting Extrasolar Planets", The Astrophysical Journal, 742 (2): 116, arXiv:1008.3388, Bibcode:2011ApJ...742..116B, doi:10.1088/0004-637X/742/2/116, S2CID 119182075.
- Mancini, L.; et al. (2018), "The GAPS programme with HARPS-N at TNG XVI. Measurement of the Rossiter-McLaughlin effect of transiting planetary systems HAT-P-3, HAT-P-12, HAT-P-22, WASP-39, and WASP-60", Astronomy & Astrophysics, A41: 613, arXiv:1802.03859, Bibcode:2018A&A...613A..41M, doi:10.1051/0004-6361/201732234, S2CID 73565379.
- "HD 233731". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2015-12-10.
- Piskorz, Danielle; et al. (2015), "Friends of Hot Jupiters. III. An Infrared Spectroscopic Search for Low-Mass Stellar Companions", The Astrophysical Journal, 814 (2): 148, arXiv:1510.08062, Bibcode:2015ApJ...814..148P, doi:10.1088/0004-637X/814/2/148, S2CID 11525988.
- Turner, Jake D.; et al. (2016), "Ground-based near-UV observations of 15 transiting exoplanets: Constraints on their atmospheres and no evidence for asymmetrical transits", Monthly Notices of the Royal Astronomical Society, 459: 789–819, arXiv:1603.02587, Bibcode:2016MNRAS.459..789T, doi:10.1093/mnras/stw574, S2CID 8769245.
- Bonomo, A. S.; et al. (2017), "The GAPS Programme with HARPS-N at TNG. XIV. Investigating giant planet migration history via improved eccentricity and mass determination for 231 transiting planets", Astronomy and Astrophysics, 602, A107, arXiv:1704.00373, Bibcode:2017A&A...602A.107B, doi:10.1051/0004-6361/201629882.