WASP-121, also known as CD-38 3220, is a magnitude 10.4 star located approximately 858 light-years (263 parsecs) away in the constellation Puppis.[1] WASP-121 has a mass and radius similar to the Sun's. It hosts one known exoplanet.
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Puppis[1] |
| Right ascension | 07h 10m 24.06046s[2] |
| Declination | −39° 05′ 50.5712″[2] |
| Apparent magnitude (V) | 10.4 |
| Characteristics | |
| Spectral type | F6V[3][4] |
| Apparent magnitude (B) | 11.00[5] |
| Apparent magnitude (V) | 10.51[5] |
| Apparent magnitude (J) | 9.625[5] |
| Apparent magnitude (H) | 9.439[5] |
| Apparent magnitude (K) | 9.374[5] |
| Astrometry | |
| Radial velocity (Rv) | 38.25±0.22[2] km/s |
| Proper motion (μ) | RA: −3.735 mas/yr[2] Dec.: 25.663 mas/yr[2] |
| Parallax (π) | 3.7996 ± 0.0104 mas[2] |
| Distance | 858 ± 2 ly (263.2 ± 0.7 pc) |
| Details | |
| Mass | 1.353[3] M☉ |
| Radius | 1.458[3] R☉ |
| Temperature | 6,460.0[3] K |
| Metallicity [Fe/H] | 0.13[3] dex |
| Rotational velocity (v sin i) | 11.90±0.31[6] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
The star, although metal-rich in terms of overall contents of heavy elements, is depleted of carbon. The carbon to oxygen molar ratio of 0.23±0.05 for WASP-121 is well below the solar ratio of 0.55.[7]
Nomenclature
The designation WASP-121 indicates that this was the 121st star found to have a planet by the Wide Angle Search for Planets.
In August 2022, this planetary system was included among 20 systems to be named by the third NameExoWorlds project.[8] The approved names, proposed by a team from Bahrain, were announced in June 2023. WASP-121 is named Dilmun after the ancient civilization, and its planet is named Tylos after the ancient Greek name for Bahrain.[9]
Planetary system
In 2015, the exoplanet WASP-121b was discovered orbiting WASP-121 by the transit method.[3][10] WASP-121b is a hot Jupiter with a mass about 1.18 times that of Jupiter and a radius about 1.81 times that of Jupiter.[4][11] The exoplanet orbits WASP-121, its host star, every 1.27 days.[4][11] Hot water molecules have been found in the stratosphere of WASP-121b (i.e., the atmospheric layer in which temperatures increase as the altitude increases).[3][11][12][13]
| Companion (in order from star) | Mass | Semimajor axis (AU) | Orbital period (days) | Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b / Tylos | 1.184[3][4] MJ | 0.02544[3] | 1.275[3] | 0.0[3] | 87.6[3]° | 1.81[4] RJ |
Gallery
WASP-121b – computer-simulated views (August 2018)
An artist's impression of a hot Jupiter planet
