WASP-21
Star in the constellation Pegasus From Wikipedia, the free encyclopedia
WASP-21 is a G-type star (spectral type G3V) that is reaching the end of its main sequence lifetime[4][5] approximately 850 light years from Earth in the constellation of Pegasus. The star is relatively metal-poor, having 40% of heavy elements compared to the Sun.[5] Kinematically, WASP-21 belongs to the thick disk of the Milky Way.[1] It has an exoplanet named WASP-21b. [6]
Size comparison between Sun and WASP-21 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Pegasus |
| Right ascension | 23h 09m 58.25s[1] |
| Declination | +18° 23′ 45.9″[1] |
| Apparent magnitude (V) | 11.58 ± 0.08[1] |
| Characteristics | |
| Spectral type | G3V |
| Astrometry | |
| Radial velocity (Rv) | -89.45 [1] km/s |
| Proper motion (μ) | RA: 17.597 ± 0.074 [2] mas/yr Dec.: 18.867 ± 0.05 [2] mas/yr |
| Parallax (π) | 3.8412±0.0427 mas[2] |
| Distance | 849 ± 9 ly (260 ± 3 pc) |
| Absolute magnitude (MV) | 4.97 |
| Details | |
| Mass | 0.89 ± 0.071[3] M☉ |
| Radius | 1.136 ± 0.049[3] R☉ |
| Surface gravity (log g) | 4.277 ± 0.025[3] cgs |
| Temperature | 5800 ± 100[1] K |
| Metallicity | -0.4 ± 0.1 [1] |
| Metallicity [Fe/H] | -0.46 ± 0.11 [1] dex |
| Rotational velocity (v sin i) | 1.5 ± 0.6 [1] km/s |
| Age | 12 ± 5[1] Gyr |
| Other designations | |
| Tangra, GSC 01715-00679, 2MASS J23095825+1823459, Gaia DR2 2831084391023184128 | |
| Database references | |
| SIMBAD | data |
The survey in 2012 have failed to find any stellar companions to WASP-21.[7]
Naming
In 2019 the WASP-21 system was chosen as part of the NameExoWorlds campaign organised by the International Astronomical Union, which assigned each country a star and planet to be named. WASP-21 was assigned to Bulgaria. The winning proposal named the star Tangra after a deity worshipped by the early Bulgars, and the planet Bendida after a deity worshipped by the Thracians.[8]
Planetary System
In 2010 WASP-21 was discovered to host a hot Jupiter type planet by the Wide Angle Search for Planets (WASP).[1] and confirmed by radial velocity by the WASP team in 2010.
Transit-timing variation analysis in 2015 did not find an additional planets in the system.[5]
In 2020, spectroscopic analysis has found the WASP-21 b atmosphere is mostly cloudless and contains sodium.[9]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b / Bendida | 0.276 ± 0.018 MJ | 0.0499 ± 0.0013 | 4.322482 | 0.0 [1] | 86.97 ± 0.33° | 1.162 RJ |
References
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