Upsilon Andromedae e is the proposed outermost extrasolar planet orbiting the star Upsilon Andromedae in the constellation of Andromeda. If it exists, this planet would be one of the most Jupiter-like exoplanets found in terms of mass and semi-major axis. However, subsequent studies have found that the apparent planetary signal is more likely to be an instrumental artifact.[3][4]
This planet was discovered on November 22, 2010, but the discovery paper was not released until December 2.[1] It was the fourth time in 2010 that a fourth planet has been discovered in a planetary system, the others being Gliese 876 e, HD 10180 e, and HR 8799 e; in no earlier year during the exoplanet era had more than one fourth planet been discovered.
Subsequent studies in 2011 and 2014, while finding some evidence for a fourth planet, found large inconsistencies in the estimated orbital period of Upsilon Andromedae e depending on what dataset was used,[5] suggesting that the apparent planetary signal is more likely to be an instrumental artifact.[3][4]
Astronomers initially thought that a fourth planet in this system could not exist because it would have made the planetary system unstable and would have been ejected.[6] But in 2007, an island region of stability was reported where a fourth planet could exist.[7]
Characteristics
If it exists, Upsilon Andromedae e would have a minimum mass slightly greater than Jupiter's and orbit at a similar distance as Jupiter from the Sun, at 5.2456 astronomical unit|AU compared to 5.2043 AU for Jupiter. Although only the minimum mass is determined since inclination is not yet known, its true mass might be much greater. It would take over a decade to orbit the star. At an eccentricity of 0.00536, the planet's orbit would be more circular than that of any of the planets in the Solar System.[1]
See also
HIP 11915 b – another Jupiter analog discovered in 2015
↑Tuomi, M.; Pinfield, D.; Jones, H. R. A. (2014). "Application of Bayesian model inadequacy criterion for multiple data sets to radial velocity models of exoplanet systems". Astronomy & Astrophysics532: A116. doi:10.1051/0004-6361/201117278. Bibcode: 2011A&A...532A.116T.
