Astronomy:HAT-P-21
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Ursa Major |
| Right ascension | 11h 25m 05.9858s[1] |
| Declination | +41° 01′ 40.6692″[1] |
| Apparent magnitude (V) | 11.46[1] |
| Characteristics | |
| Spectral type | G3V |
| Astrometry | |
| Radial velocity (Rv) | -51.98 km/s |
| Proper motion (μ) | RA: -1.088 mas/yr Dec.: 13.243 mas/yr |
| Parallax (π) | 3.5781 ± 0.0410[1] mas |
| Distance | 910 ± 10 ly (279 ± 3 pc) |
| Details[2][3] | |
| Mass | 0.947±0.042 M☉ |
| Radius | 1.105±0.083 R☉ |
| Luminosity | 1.06+0.20−0.16 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[4] |
| Rotational velocity (v sin i) | 3.5±0.5 km/s |
| Age | 10.2±2.5 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
HAT-P-21 is a G-type main-sequence star about 910 light-years away. The star has amount of metals similar to solar abundance. The survey in 2015 has failed to detect any stellar companions.[5] The star is rotating rapidly, being spun up by the tides of giant planet on close orbit.[3]
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.[6] 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.[7] 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.[4]
The planetary orbit is likely aligned with the equatorial plane of the star, misalignment equal to 25±16 degrees.[8]
| 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
- ↑ 1.0 1.1 1.2 1.3 1.4 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, doi:10.3847/1538-3881/aa5df3, Bibcode: 2017AJ....153..136S
- ↑ 3.0 3.1 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, doi:10.1051/0004-6361/201525774, Bibcode: 2015A&A...577A..90M
- ↑ 4.0 4.1 Damiani, C.; Lanza, A. F. (2011), "Prospecting transit duration variations in extrasolar planetary systems", Astronomy & Astrophysics 535: A116, doi:10.1051/0004-6361/201117207, Bibcode: 2011A&A...535A.116D
- ↑ 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, doi:10.1051/0004-6361/201424091, Bibcode: 2015A&A...575A..23W
- ↑ "IAU 100 NameExoWorlds Approved Names". http://www.nameexoworlds.iau.org/final-results.
- ↑ 7.0 7.1 Bakos, G. Á.; Hartman, J.; Torres, G.; Latham, D. W.; Kovács, Géza; Noyes, R. W.; Fischer, D. A.; Johnson, J. A. et al. (2010), "HAT-P-20b–HAT-P-23b: FOUR MASSIVE TRANSITING EXTRASOLAR PLANETS", The Astrophysical Journal 742 (2): 116, doi:10.1088/0004-637X/742/2/116
- ↑ Mancini, L. et al. (2022), "The GAPS Programme at TNG", Astronomy & Astrophysics 664: A162, doi:10.1051/0004-6361/202243742
- ↑ Davoudi, F.; Jafarzadeh, S.J.; Poro, A.; Basturk, O.; Mesforoush, S.; Fasihi Harandi, A.; Gozarandi, M.J.; Zare Mehrjardi, Z. et al. (2020), "Light Curve Analysis of Ground‐Based Data from Exoplanets Transit Database", New Astronomy 76: 101305, doi:10.1016/j.newast.2019.101305, Bibcode: 2020NewA...7601305D
Coordinates: 
11h 25m 05.9858s, +41° 01′ 40.6692″
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