Upsilon Andromedae
 A conception of Upsilon Andromedae A, here showing 2 out of 4 known planets. |
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| Observation data Epoch J2000.0 Equinox J2000.0 |
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|---|---|
| Constellation | Andromeda |
| Right ascension | 01h 36m 47.84216s |
| Declination | +41° 24′ 19.6443″ |
| Apparent magnitude (V) | 4.09 |
| Characteristics | |
| Spectral type | F8V + M4.5V |
| Apparent magnitude (B) | 4.63 |
| U−B color index | 0.06 |
| B−V color index | 0.54 |
| V−R color index | 0.30 |
| R−I color index | 0.30 |
| Astrometry | |
| Radial velocity (Rv) | −28.9±0.9 km/s |
| Proper motion (μ) |
RA: −173.33±0.20 mas/yr Dec.: −381.80±0.13 mas/yr |
| Parallax (π) | 73.71 ± 0.10mas |
| Distance | 44.25 ± 0.06 ly (13.57 ± 0.02 pc) |
| Absolute magnitude (MV) | 3.44±0.02 |
| Details | |
| υ And A | |
| Mass | 1.27±0.06 M☉ |
| Radius | 1.480±0.087 R☉ |
| Luminosity | 3.57 L☉ |
| Surface gravity (log g) | 4.0±0.1 cgs |
| Temperature | 6213±44 K |
| Metallicity [Fe/H] | 0.09±0.06 dex |
| Rotation | 7.3±0.04 d |
| Rotational velocity (v sin i) | 9.5±0.8 km/s |
| Age | 3.12 ± 0.2 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Extrasolar Planets Encyclopaedia |
data |
| Data sources: | |
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Hipparcos Catalogue, CCDM (2002), Bright Star Catalogue (5th rev. ed.) |
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Upsilon Andromedae (υ Andromedae, abbreviated Upsilon And, υ And) is a binary star located approximately 44 light-years from Earth in the constellation of Andromeda. The system consists of an F-type main-sequence star (designated υ Andromedae A, also named Titawin) and a smaller red dwarf (υ Andromedae B).
As of 2010[update], four extrasolar planets (designated Upsilon Andromedae b, c, d and e; the first three named Saffar, Samh and Majriti, respectively) are believed to orbit υ Andromedae A. All four are likely to be jovian planets that are comparable in size to Jupiter. This was both the first multiple-planet system to be discovered around a main-sequence star, and the first multiple-planet system known in a multiple star system.
υ Andromedae (Latinised to Upsilon Andromedae) is the system's Bayer designation. Under the rules for naming objects in binary star systems, the two components are designated A and B. Under the same rules, the first planet discovered orbiting υ Andromedae A should be designated υ Andromedae Ab. Though this more formal form is occasionally used to avoid confusion with the secondary star υ Andromedae B, it is more commonly referred to as υ Andromedae b. The other planets discovered were designated υ Andromedae c, d, and e, in order of their discovery.
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