Upsilon Andromedae
Star
Upsilon Andromedae (Titawin) - a yellow-white star a little hotter and larger than the Sun, 44 light-years away in Andromeda, and a milestone of exoplanet science: in 1999 it became the first ordinary star found to host MORE THAN ONE planet. Three giant planets are known, on markedly tilted, non-aligned orbits.
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Key facts
Mass
2.59 × 10³⁰ kg
1.3 M☉
Radius
1,085,292 km
1.56× wider than the Sun
Surface temperature
6,157 K (5884 °C)
Luminosity
1.28 × 10²⁷ W
Spectral type
F8V (yellow-white)
Science
Physical
- Mass
- 2.59 × 10³⁰ kg · 1.3 M☉
- Radius
- 1,085,292 km · 1.56× wider than the Sun
- Density
- 483 kg/m³ · 0.48× water
- Spectral type
- F8V (yellow-white)
Rotation
- Note
- Rotates faster than the Sun (~7–12 days), as F-type stars do.
Composition
- By mass
- A hydrogen/helium star a little more massive, hotter and brighter than the Sun, with a faint red-dwarf companion. Its three giant planets and their misaligned orbits make it a natural laboratory for how planetary systems are stirred up after they form.
Temperature
- Surface
- 6,157 K (5884 °C)
Radiation & temperature
- Luminosity
- 1.28 × 10²⁷ W · 3.35 L☉
- Surface temperature
- 6,157 K (5884 °C)
- Peak wavelength
- 471 nm · blue light
Discovery & history
- Method
- Naked-eye star
- Name
- Its IAU name Titawin (from the old name of the Moroccan city Tetouan) was chosen in 2015; it is Upsilon Andromedae, a star of the Chained Princess.
Its innermost hot Jupiter was found in 1996; in 1999 two more giants were announced, making Upsilon Andromedae the first multi-planet system around a main-sequence star. Later astrometry showed the outer planets' orbits are steeply inclined to one another - evidence of a violent dynamical past.
Images
Images from open archives · credit shown per image