NASA (Exoplanet Catalog artwork)Upsilon Andromedae b
also named SaffarPart of the first multi-planet system found around a normal star
Overview
Upsilon Andromedae b, formally named Saffar, is an extrasolar planet approximately 44 light-years away from the Sun in the constellation of Andromeda. The planet orbits its host star, the F-type main-sequence star Upsilon Andromedae A, approximately every five days. Discovered in June 1996 by Geoffrey Marcy and R. Paul Butler, it was one of the first hot Jupiters to be discovered. It is also one of the first non-resolved planets to be detected directly. Upsilon Andromedae b is the innermost-known planet in its planetary system.
Source: Wikipedia
NASA: Upsilon Andromedae b is a gas giant exoplanet that orbits a F-type star. Its mass is 0.6876 Jupiters, it takes 4.6 days to complete one orbit of its star, and is 0.05922166 AU from its star. Its discovery was announced in 1996.
Why it matters
- Its two outer siblings, announced in 1999, made Upsilon Andromedae the first known multi-planet system around a main-sequence star.
- A hot Jupiter on a 4.6-day orbit, with Spitzer showing its hottest point is offset far from the substellar point.
- The outer planets' orbits are steeply inclined to each other — evidence of a violent dynamical past.
NASA puts it this way: “Upsilon Andromedae b is a gas giant exoplanet that orbits an F-type star. Its mass is 0.6876 Jupiters, it takes 4.6 days to complete one orbit of its star, and is 0.059222 AU from its star. Its discovery was announced in 1996.”
Discovery & system
- Discovered
- 1996 · Radial Velocity · Lick Observatory
- Discovery paper
- Butler et al. 1997
- Discoverers
- Geoffrey Marcy, R. Paul Butler
- Host star
- ups And · F8 V · 6,157 K · 1.3 M☉
- System
- 3 known planets, 2 stars
- Siblings
- ups And c, ups And d
The system
| World | Period | Distance | Radius | Mass | Temp. |
|---|---|---|---|---|---|
| ups And b | 4.62 d | 0.059 AU | 1.25 R♃ | ≥ 0.69 M♃ | 1,524 K |
| ups And c | 241.3 d | 0.828 AU | 1.1 R♃ | 13.98 M♃ | 408 K |
| ups And d | 3.5 yr | 2.51 AU | 1.12 R♃ | 10.25 M♃ | 234 K |
By the numbers
- Radius
- 1.25 R♃14 R⊕
- Mass
- ≥ 0.69 M♃219 M⊕ · minimum mass (M sin i)
- Orbital period
- 4.62 d0.01 yr
- Distance from star
- 0.059 AU8.86 million km
- Eccentricity
- 0.022nearly circular
- Equilibrium temp.
- 1,524 K1,251 °C
- Starlight received
- 956 × Earth
- Distance from Earth
- 43.7 ly13.4 pc
- Density
- 0.44 g/cm³0.08 × Earth
Sources
Image: NASA (Exoplanet Catalog artwork) · NASA media: generally free of copyright · image page
Text: Wikipedia (CC BY-SA 4.0). Taglines and highlights are editorial.