| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Ursa Major |
| Right ascension | 11 25 05.9859 |
| Declination | +41° 01′ 40.665″ |
| Apparent magnitude (V) | 11.46 |
| Characteristics | |
| Spectral type | G3V |
| Astrometry | |
| Radial velocity (Rv) | -51.98 km/s |
| Proper motion (μ) | RA: −1.142(17) mas/yr Dec.: 13.523(24) mas/yr |
| Parallax (π) | 3.5190 ± 0.0228 mas |
| Distance | 927 ± 6 ly (284 ± 2 pc) |
| Details | |
| Mass | 0.947±0.042 M☉ |
| Radius | 1.105±0.083 R☉ |
| Luminosity | 1.06 −0.16 L☉ |
| Surface gravity (log g) | 4.33±0.06 cgs |
| Temperature | 5634±67 K |
| Metallicity | 0.04±0.08 |
| Rotation | 15.88±0.02 d |
| Rotational velocity (v sin i) | 3.5±0.5 km/s |
| Age | 10.2±2.5 Gyr |
| Other designations | |
| Mazalaai, Gaia DR3 770622651659107712, TYC 3013-1229-1, GSC 03013-01229, 2MASS J11250598+4101406 | |
| Database references | |
| SIMBAD | data |
HAT-P-21 is a G-type main-sequence star about 927 light-years away. The star has amount of metals similar to solar abundance. The survey in 2015 has failed to detect any stellar companions. The star is rotating rapidly, being spun up by the tides of giant planet on close orbit.
Naming
In 2019, the HAT-P-21 star received the proper name Mazalaai while its planet HAT-P-21b received the name Bambaruush at an international NameExoWorlds contest. These names refer to the Mongolian name for the endangered Gobi bear subspecies, and the Mongolian term for 'bear cub', respectively.
Planetary system
In 2010 a transiting hot super-Jovian planet on moderately eccentric orbit was detected. Its equilibrium temperature is 1283±50 K. The transit-timing variation survey in 2011 have failed to rule out or confirm the existence of additional planets in the system, until the orbital parameters of HAT-P-21b are known with better precision.
The planetary orbit is likely aligned with the equatorial plane of the star, misalignment equal to 25±16 degrees.
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b (Bambaruush) | 4.063±0.161 MJ | 0.0494±0.0007 | 4.124481±0.000007 | 0.228±0.016 | 88.6° | 1.08±0.18 RJ |
References
- ^ Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ HAT-P-21 -- Star
- Stassun, Keivan G.; Collins, Karen A.; Gaudi, B. Scott (2016), "Accurate Empirical Radii and Masses of Planets and Their Host Stars with Gaia Parallaxes", The Astronomical Journal, 153 (3): 136, arXiv:1609.04389, Bibcode:2017AJ....153..136S, doi:10.3847/1538-3881/aa5df3, S2CID 119219062
- ^ Maxted, P. F. L.; Serenelli, A. M.; Southworth, J. (2015), "A comparison of gyrochronological and isochronal age estimates for transiting exoplanet host stars", Astronomy & Astrophysics, 577: A90, arXiv:1503.09111, Bibcode:2015A&A...577A..90M, doi:10.1051/0004-6361/201525774, S2CID 53324330
- ^ Damiani, C.; Lanza, A. F. (2011), "Prospecting transit duration variations in extrasolar planetary systems", Astronomy & Astrophysics, 535: A116, arXiv:1109.0936, Bibcode:2011A&A...535A.116D, doi:10.1051/0004-6361/201117207, S2CID 118460941
- Wöllert, Maria; Brandner, Wolfgang; Bergfors, Carolina; Henning, Thomas (2015), "A Lucky Imaging search for stellar companions to transiting planet host stars", Astronomy & Astrophysics, 575: A23, arXiv:1507.01938, Bibcode:2015A&A...575A..23W, doi:10.1051/0004-6361/201424091, S2CID 119250579
- "IAU 100 NameExoWorlds Approved Names". Archived from the original on 2019-12-19. Retrieved 2020-07-08.
- ^ Bakos, G. Á.; Hartman, J.; Torres, G.; Latham, D. W.; Kovács, Géza; Noyes, R. W.; Fischer, D. A.; Johnson, J. A.; Marcy, G. W.; Howard, A. W.; Kipping, D.; Esquerdo, G. A.; Shporer, A.; Béky, B.; Buchhave, L. A.; Perumpilly, G.; Everett, M.; Sasselov, D. D.; Stefanik, R. P.; Lázár, J.; Papp, I.; Sári, P. (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. (2022), "The GAPS Programme at TNG", Astronomy & Astrophysics, 664: A162, arXiv:2205.10549, doi:10.1051/0004-6361/202243742, S2CID 248986121
- Davoudi, F.; Jafarzadeh, S.J.; Poro, A.; Basturk, O.; Mesforoush, S.; Fasihi Harandi, A.; Gozarandi, M.J.; Zare Mehrjardi, Z.; Maley, P.D.; Khakpash, S.; Rokni, K.; Sarostad, A. (2020), "Light Curve Analysis of Ground-Based Data from Exoplanets Transit Database", New Astronomy, 76: 101305, arXiv:1910.11438, Bibcode:2020NewA...7601305D, doi:10.1016/j.newast.2019.101305, S2CID 202931761
