Upsilon Andromedae
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{{Starbox begin | name = Upsilon Andromedae A / B }} {{Starbox image | image = Image:And-s.jpg | caption = Upsilon Andromedae (circled) in Andromeda }} {{Starbox observe | epoch = J2000.0 | constell = Andromeda | ra = 01h 36m 47.8s | dec = +41° 24' 20" | appmag_v = +4.09 }} {{Starbox character | class = F8V / M4.5V | b-v = 0.54 / | u-b = 0.06 / | variable = none / ? }} {{Starbox astrometry | radial_v = -28.9 / | prop_mo_ra = -172.57 / ? | prop_mo_dec = -381.03 / ? | parallax = 74.25 / ? | p_error = 0.72 / ? | dist_ly = 43.9 | dist_pc = 13.5 | absmag_v = 3.96 / ? }} {{Starbox detail | mass = 1.3 / ? | radius = 1.6 / ? | luminosity = 3.4 / ? | temperature = 6,000 / ? | metal = 134% / ? | rotation = ~8 km/sec. / | age = 3 × 109 / ? }} {{Starbox catalog | names = 50 Andromedae, Gl 61, HR 458, BD +40°332, HD 9826, LTT 10561, GCTP 331.00, SAO 37362, FK5 1045, GC 1948, CCDM 01367+4125, WDS 01368+4124A, HIP 7513. }} Template:Starbox end
Upsilon Andromedae (υ And for short) is a binary star, approximately 44 light-years away in the constellation Andromeda, and approximately 3 billion years old, two thirds the age of our Sun, about 10 degrees east of the Andromeda Galaxy. The main star is rather similar to the sun but slightly hotter and brighter, of spectral type F8V.
As of 1999, Upsilon Andromedae was the first main sequence star determined to have more than one extrasolar planet. So far, three planets have been discovered within the system; all three are believed to be gas giants.
The companion star is a red dwarf of spectral type M4.5V located at an estimated distance of 750 AU from the primary star.
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Planets
The innermost planet (b) was discovered in 1996 and announced in January of 1997 by Geoffrey Marcy and R. Paul Butler, both astronomers at San Francisco State University (SFSU). Because of its closeness to the parent star, it induced a large wobble which was detected relatively easily. However, some additional wobble in the star remained unexplained, and it was suggested there might be a second planet in orbit. In the end, astronomers at both SFSU and the Harvard-Smithsonian Center for Astrophysics independently concluded that, in fact, a three-planet model best fit the data. These results were announced on April 15, 1999.
The existence of further planets too small to detect has not been ruled out.
The companion star was discovered in 2002, making υ Andromedae the first multiple planetary system in a multiple star system known. Template:Clear
Upsilon Andromedae Ab
{{Extrasolar Planet | name = Upsilon Andromedae Ab | image = Image:UpsAnd-b.jpg Upsilon Andromedae Ab and hypothetical moons | semimajor = 0.059 | eccentricity = 0.012 (± 0.15) | period = 4.617 (± 0.0003) | long_peri = 73 | t_peri = 2,450,002.093 | mass = 0.69 | discovery_date = 1996 | discovery_method = Doppler Spectroscopy | discoverers = Marcy et al. }}
Upsilon Andromedae Ab is the innermost extrasolar planet orbiting in the Upsilon Andromedae system. It was one of the first hot Jupiters to be discovered. The planet has a comparable mass to the jovian planets in our solar system. Template:Clear
Upsilon Andromedae Ac
{{Extrasolar Planet | name = Upsilon Andromedae Ac | image = Image:UpsAnd-c.jpg Upsilon Andromedae Ac (blue) | semimajor = 0.829 | eccentricity = 0.28 (± 0.11) | period = 241.5 (± 1.1) | long_peri = 250 | t_peri = 2,450,160.5 | mass = 1.89 | discovery_date = 1999 | discovery_method = Doppler Spectroscopy | discoverers = Marcy et al. }}
Upsilon Andromedae Ac is the middle extrasolar planet orbiting in the Upsilon Andromedae system. Twice the mass of Jupiter, it orbits in an eccentric orbit closer to the star than Earth is to the Sun. The high mass of the planet indicates that it is likely to be a jovian planet. According to simulations, gravitational interactions with the outer planet result in the eccentricity of the orbit of planet Ac changing over time, with the orbit becoming circular roughly once every 7,000 years. This situation is highly unusual (in general, orbits would not circularise in this way) and is thought to be the result of planet-planet scattering in the early history of the Upsilon Andromedae system. Template:Clear
Upsilon Andromedae Ad
{{Extrasolar Planet | name = Upsilon Andromedae Ad | image = Image:UpsAnd-d.jpg Upsilon Andromedae Ad | semimajor = 2.53 | eccentricity = 0.27 (± 0.11) | period = 1284 (± 30) | long_peri = 260 | t_peri = 2,450,064 | mass = 3.75 | discovery_date = 1999 | discovery_method = Doppler Spectroscopy | discoverers = Marcy et al. }}
Upsilon Andromedae Ad is the last extrasolar planet orbiting in the Upsilon Andromedae system. Based on its high mass it is thought to be a jovian planet. It has an eccentric orbit in the outer part of the star's habitable zone. Template:Clear
See also
External links
- Extrasolar Planets Encyclopaedia: Ups And
- SIMBAD: HD 9826 -- High proper-motion Star
- SIMBAD: BD+40 332B -- Star in double system
- SFSU: Upsilon Andromedae
- Harvard-Smithsonian CfA: Upsilon Andromedae
- Extrasolar Visions: Upsilon Andromedae
- SpaceDaily: How The Orbits Of Extrasolar Planets Became So Eccentric
- Planet Project: Upsilon Andromedae
- Astro Encyclopedia: Upsilon Andromedae
Template:Star-stub Template:Exoplanet-stubde:Ypsilon Andromedae es:Upsilon Andromedae it:Upsilon Andromedae pl:Ypsilon Andromedae ru:Υ Андромеды sk:Ypsilon Andromedae