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Upsilon Andromedae

A double star of a big yellow main sequence star and a far distant red dwarf. The bigger of the two, star A, has at least three planets.

The planets:
Upsilon Andromedae b: 0.71 times mass of Jupiter, 4.617 days orbit period. The temperature difference of the day and the night side is 1400 Kelvin.
Upsilon Andromedae c: 2.11 times mass of Jupiter, 241.2 days orbit period. The planet is very warm but could be on the inner edge of the life zone.
Upsilon Andromedae d: 4.61 times mass of Jupiter, 3.47 years orbit period. The planet is rather cool but could be on the outer edge of the life zone.

Constellation: Andromeda
Age: 2.9 - 4.1 billion years
Distance: 43.93 light-years
Radial velocity: -28.7 km/sec
Orbit period of Upsilon Andromedae A and B: 20 000 years

Upsilon Andromedae A

Spectral class: F8
Visual magnitude: 4.09
Luminosity: 3.650 * Sun
Mass: 1.2 * Sun
Diameter: 1.737 * Sun

Upsilon Andromedae B

Spectral class: M4.5

Mass: 0.2 * Sun

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    Upsilon Andromedae
Upsilon Andromedae compared to our solar system.
Graphic: Harvard-Smithsonian Center for Astrophysics / A. Contos

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