Pollux
Star
Pollux - the brighter of Gemini's twin stars and the nearest giant star to the Sun with a known planet, 33.8 light-years away. An orange giant about nine times the Sun's width, it has swollen and cooled at the end of its life. Its planet, Pollux b (Thestias), is a super-Jupiter on a nearly circular orbit.
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Key facts
Mass
3.98 × 10³⁰ kg
2 M☉
Radius
6,191,730 km
8.9× wider than the Sun
Surface temperature
4,893 K (4620 °C)
Luminosity
1.57 × 10²⁸ W
Spectral type
K0III (orange giant)
Science
Physical
- Mass
- 3.98 × 10³⁰ kg · 2 M☉
- Radius
- 6,191,730 km · 8.9× wider than the Sun
- Density
- 4 kg/m³ · 0.004× water
- Spectral type
- K0III (orange giant)
Rotation
- Note
- A slowly-rotating giant; its steady, low-amplitude wobble revealed the orbiting planet.
Composition
- By mass
- An evolved orange giant of about two solar masses that has exhausted its core hydrogen, swelling to some nine times the Sun's width and cooling to an orange glow. It shines about 40 times as bright as the Sun — a preview of what our own star will become in billions of years.
Temperature
- Surface
- 4,893 K (4620 °C)
Radiation & temperature
- Luminosity
- 1.57 × 10²⁸ W · 40.9 L☉
- Surface temperature
- 4,893 K (4620 °C)
- Peak wavelength
- 592 nm · orange light
Discovery & history
- Method
- Naked-eye star
- Name
- Its IAU proper name Pollux is one of the mythological Gemini twins (with Castor); it is Beta Geminorum, though in fact the brightest star of Gemini.
Known since antiquity as one of the Gemini twins, Pollux was found in 2006 to host a giant planet from a decades-long radial-velocity wobble tracked at McDonald Observatory - one of the first planets found around a giant star.
Images
Images from open archives · credit shown per image