HD 189733
Star
HD 189733 - an orange dwarf 64.5 light-years away in Vulpecula, orbited by one of the most intensely studied planets beyond the Solar System: a transiting hot Jupiter whose deep-blue colour and violent weather have been measured directly. Because the planet both transits and is nearby, it has become a workhorse for reading exoplanet atmospheres.
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Key facts
Mass
1.57 × 10³⁰ kg
0.79 M☉
Radius
521,775 km
75% of the Sun's radius
Surface temperature
5,052 K (4779 °C)
Luminosity
1.32 × 10²⁶ W
Spectral type
K2V (orange dwarf)
Science
Physical
- Mass
- 1.57 × 10³⁰ kg · 0.79 M☉
- Radius
- 521,775 km · 75% of the Sun's radius
- Density
- 2,641 kg/m³ · 2.6× water
- Spectral type
- K2V (orange dwarf)
Rotation
- Note
- Rotates about once every 12 days; its starspots are seen as the planet crosses them.
Composition
- By mass
- A hydrogen/helium orange dwarf a bit cooler and smaller than the Sun, with a faint red-dwarf companion. It is moderately active, but bright and close enough that its transiting giant planet has become the reference world for reading exoplanet skies.
Temperature
- Surface
- 5,052 K (4779 °C)
Radiation & temperature
- Luminosity
- 1.32 × 10²⁶ W · 0.346 L☉
- Surface temperature
- 5,052 K (4779 °C)
- Peak wavelength
- 574 nm · yellow light
Discovery & history
- Name
- A catalogue designation (Henry Draper 189733); the star also carries the variable-star name V452 Vulpeculae.
The transiting giant was found in 2005. Being bright and close, it let astronomers make firsts in exoplanet science: a temperature map (2007), the detection of its true colour - deep blue - from Hubble (2013), and measurements of ferocious ~8,000 km/h winds and possible sideways-raining glass. Its blue is scattered light, not an ocean.
Images
Images from open archives · credit shown per image