WASP-121

Star

WASP-121 — a hot, bright F-type star about half again the Sun's size and near the end of its main-sequence life, ~880 light-years away in Puppis. Its fierce output drives the extreme, evaporating atmosphere of its ultra-hot Jupiter.

Open in 3D viewSee WASP-121 in the live, interactive 3D map

Key facts

Mass

2.65 × 10³⁰ kg

1.33 M☉

Radius

1,016,418 km

1.46× wider than the Sun

Surface temperature

6,628 K (6355 °C)

Luminosity

1.42 × 10²⁷ W

Spectral type

F6V (yellow-white dwarf)

Science

Physical

Mass: 2.65 × 10³⁰ kg · 1.33 M☉
Radius: 1,016,418 km · 1.46× wider than the Sun
Density: 601 kg/m³ · 0.6× water
Spectral type: F6V (yellow-white dwarf)

Rotation

Note: A hot, fairly rapidly rotating F star — bright enough for exquisitely detailed atmospheric spectroscopy of its planet.

Composition

By mass: A hot F-type star about half again the Sun's size (~1.5× its radius) and near the end of its main-sequence life. Its fierce output is what heats and inflates its ultra-hot Jupiter and drives the metals off it.

Temperature

Surface: 6,628 K (6355 °C)

Radiation & temperature

Luminosity: 1.42 × 10²⁷ W · 3.71 L☉
Surface temperature: 6,628 K (6355 °C)
Peak wavelength: 437 nm · violet-blue light

Discovery & history

Name: A WASP-survey catalogue designation; no proper name.

Catalogued by the WASP survey, which in 2015 saw a giant planet transiting it on a punishingly tight orbit — since studied intensively as a laboratory for extreme planetary atmospheres.

Images

Where to find it — in Puppis, the Stern (IAU constellation chart). To the eye it is a single point of light; no telescope has imaged its surface. — IAU / Sky & Telescope, R. Sinnott & R. Fienberg (CC BY 3.0) · Wikimedia Commons

Images from open archives · credit shown per image