NASA (Exoplanet Catalog artwork)WASP-121b
also named TylosAn ultra-hot Jupiter with a mapped 3D atmosphere and metals escaping to space
Overview
WASP-121b, officially named Tylos, is an exoplanet orbiting the star WASP-121. WASP-121b is the first exoplanet found with an extrasolar planetary stratosphere and the first that contains water. WASP-121b is in the constellation Puppis, and is about 858 light-years from Earth.
Source: Wikipedia
NASA: WASP-121 b is a gas giant exoplanet that orbits a F-type star. Its mass is 1.17 Jupiters, it takes 1.3 days to complete one orbit of its star, and is 0.02571 AU from its star. Its discovery was announced in 2016.
Why it matters
- Hubble found a hot stratosphere with water vapour and magnesium and iron escaping the planet.
- In 2025 the VLT traced a jet stream and distinct layers in 3D, the first such map of an exoplanet.
- So close to its star that it is distorted into a rugby-ball shape.
NASA puts it this way: “WASP-121 b is a gas giant exoplanet that orbits an F-type star. Its mass is 1.157 Jupiters, it takes 1.3 days to complete one orbit of its star, and is 0.02596 AU from its star. Its discovery was announced in 2016.”
Discovery & system
- Discovered
- 2016 · Transit · SuperWASP
- Discovery paper
- Delrez et al. 2016
- Host star
- WASP-121 · F6 V · 6,628 K · 1.33 M☉
- System
- 1 known planet
The system
| World | Period | Distance | Radius | Mass | Temp. |
|---|---|---|---|---|---|
| WASP-121 b | 1.27 d | 0.026 AU | 1.74 R♃ | 1.17 M♃ | 2,409 K |
By the numbers
- Radius
- 1.74 R♃19.5 R⊕
- Mass
- 1.17 M♃372 M⊕
- Orbital period
- 1.27 d0 yr
- Distance from star
- 0.026 AU3.85 million km
- Eccentricity
- 0.009nearly circular
- Equilibrium temp.
- 2,409 K2,136 °C
- Starlight received
- 6,216 × Earth
- Distance from Earth
- 880 ly269.9 pc
- Density
- 0.28 g/cm³0.05 × Earth
Sources
Image: NASA (Exoplanet Catalog artwork) · NASA media: generally free of copyright · image page
Text: Wikipedia (CC BY-SA 4.0). Taglines and highlights are editorial.