WASP-21

WASP-21 / Tangra

Size comparison between Sun and WASP-21
Observation data
Epoch J2000      Equinox ICRS
Constellation Pegasus
Right ascension 23h 09m 58.25s
Declination +18° 23′ 45.9″
Apparent magnitude (V) 11.58±0.08
Characteristics
Evolutionary stage subgiant
Spectral type G3V
Astrometry
Radial velocity (Rv)−89.21±0.46 km/s
Proper motion (μ) RA: +17.567(21) mas/yr
Dec.: +18.639(18) mas/yr
Parallax (π)3.9089±0.0197 mas
Distance834 ± 4 ly
(256 ± 1 pc)
Absolute magnitude (MV)4.97
Details
Mass0.89±0.071 M☉
Radius1.136±0.049 R☉
Luminosity1.4 L☉
Surface gravity (log g)4.277±0.025 cgs
Temperature5,800±100 K
Metallicity−0.4±0.1
Metallicity [Fe/H]−0.46±0.11 dex
Rotational velocity (v sin i)1.5±0.6 km/s
Age12±5 Gyr
Other designations
Tangra, TOI-5963, TIC 436478932, WASP-21, GSC 01715-00679, 2MASS J23095825+1823459
Database references
SIMBADdata
Exoplanet Archivedata

WASP-21, also named Tangra, is a G-type star (spectral type G3V) that has reached the end of its main sequence lifetime. It lies approximately 834 light-years away, in the constellation of Pegasus. The star is relatively metal-poor, having 40% of heavy elements compared to the Sun. Kinematically, WASP-21 belongs to the thick disk of the Milky Way. It has an exoplanet named WASP-21b.

A survey in 2012 failed to find any stellar companions to WASP-21.

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.

Planetary system

In 2010 WASP-21 was discovered to host a hot Jupiter type planet by the Wide Angle Search for Planets (WASP), confirmed by radial velocity by the WASP team in 2010.

Transit-timing variation analysis in 2015 did not find any additional planets in the system.

In 2020, spectroscopic analysis found that the WASP-21b atmosphere is mostly cloudless and contains sodium.

The WASP-21 planetary system
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 <0.048 86.97 ± 0.33 1.162 RJ

References

  1. ↑ Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific. 99 (617): 695. Bibcode:1987PASP...99..695R. doi:10.1086/132034. Constellation record for this object at VizieR.
  2. 1 2 3 4 5 6 7 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.
  3. 1 2 3 4 5 6 7 8 9 Bouchy, F.; Hebb, L.; Skillen, I.; Collier Cameron, A.; Smalley, B.; Udry, S.; Anderson, D. R.; Boisse, I.; Enoch, B.; Haswell, C. A.; Hébrard, G.; Hellier, C.; Joshi, Y.; Kane, S. R.; Maxted, P. F. L.; Mayor, M.; Moutou, C.; Pepe, F.; Pollacco, D.; Queloz, D.; Ségransan, D.; Simpson, E. K.; Smith, A. M. S.; Stempels, H. C.; Street, R.; Triaud, A. H. M. J.; West, R. G.; Wheatley, P. J. (2010). "WASP-21b: A hot-Saturn exoplanet transiting a thick disc star". Astronomy and Astrophysics. 519: A98. arXiv:1006.2605. Bibcode:2010A&A...519A..98B. doi:10.1051/0004-6361/201014817. S2CID 119182669.
  4. 1 2 Barros, S. C. C.; Pollacco, D. L.; Gibson, N. P.; Howarth, I. D.; Keenan, F. P.; Simpson, E. K.; Skillen, I.; Steele, I. A. (2011). "A lower mass for the exoplanet WASP-21b". Monthly Notices of the Royal Astronomical Society. 416 (4): 2593–2599. arXiv:1106.2118. Bibcode:2011MNRAS.416.2593B. doi:10.1111/j.1365-2966.2011.19210.x. S2CID 56165266.
  5. ↑ Ehrenreich, D.; Désert, J. -M. (2011). "Mass-loss rates for transiting exoplanets". Astronomy and Astrophysics. 529: A136. arXiv:1103.0011. Bibcode:2011A&A...529A.136E. doi:10.1051/0004-6361/201016356.
  6. 1 2 3 4 Ciceri, S.; Mancini, L.; Southworth, J.; Nikolov, N.; Bozza, V.; Bruni, I.; Calchi Novati, S.; d'Ago, G.; Henning, Th. (2013). "Simultaneous follow-up of planetary transits: Revised physical properties for the planetary systems HAT-P-16 and WASP-21". Astronomy & Astrophysics. 557: A30. arXiv:1307.5874. Bibcode:2013A&A...557A..30C. doi:10.1051/0004-6361/201321669. S2CID 55192357.
  7. ↑ Loyd, R. O. Parke; Shkolnik, Evgenya L.; Schneider, Adam C.; Richey-Yowell, Tyler; Barman, Travis S.; Peacock, Sarah; Pagano, Isabella (2020). "Current Population Statistics do Not Favor Photoevaporation over Core-powered Mass Loss as the Dominant Cause of the Exoplanet Radius Gap". The Astrophysical Journal. 890 (1): 23. arXiv:1912.12305. Bibcode:2020ApJ...890...23L. doi:10.3847/1538-4357/ab6605.
  8. ↑ "WASP-21". SIMBAD. Centre de données astronomiques de Strasbourg.
  9. 1 2 3 4 Seeliger, M.; Kitze, M.; Errmann, R.; Richter, S.; Ohlert, J. M.; Chen, W. P.; Guo, J. K.; Göğüş, E.; Güver, T.; Aydın, B.; Mottola, S.; Hellmich, S.; Fernandez, M.; Aceituno, F. J.; Dimitrov, D.; Kjurkchieva, D.; Jensen, E.; Cohen, D.; Kundra, E.; Pribulla, T.; Vaňko, M.; Budaj, J.; Mallonn, M.; Wu, Z.-Y.; Zhou, X.; Raetz, St.; Adam, C.; Schmidt, T. O. B.; Ide, A.; et al. (2015), "Ground-based transit observations of the HAT-P-18, HAT-P-19, HAT-P-27/WASP40 and WASP-21 systems", Monthly Notices of the Royal Astronomical Society, 451 (4): 4060–4072, arXiv:1508.06215, Bibcode:2015MNRAS.451.4060S, doi:10.1093/mnras/stv1187, S2CID 56034663
  10. ↑ "Exoplanet-catalog". Exoplanet Exploration: Planets Beyond our Solar System. 2 October 2017. Retrieved 2022-12-10.
  11. ↑ 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, arXiv:1202.4586, Bibcode:2012MNRAS.421.2498G, doi:10.1111/j.1365-2966.2012.20485.x, S2CID 118573795
  12. ↑ "Bulgaria | NameExoworlds". Name Exoworlds. 2019-12-17. Retrieved 2019-12-30.
  13. ↑ Chen, G.; Casasayas-Barris, N.; Pallé, E.; Welbanks, L.; Madhusudhan, N.; Luque, R.; Murgas, F. (2020), "Detection of Na in WASP-21b's lower and upper atmosphere", Astronomy & Astrophysics, 642: A54, arXiv:2007.13429, Bibcode:2020A&A...642A..54C, doi:10.1051/0004-6361/202038661, S2CID 220793336
  14. ↑ Bonomo, A. S.; Desidera, S.; et al. (June 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 & Astrophysics. 602: A107. arXiv:1704.00373. Bibcode:2017A&A...602A.107B. doi:10.1051/0004-6361/201629882. S2CID 118923163.