Upsilon Andromedae e

Upsilon Andromedae e is the outermost extrasolar planet orbiting the star Upsilon Andromedae in the constellation of Andromeda. This planet is one of the most Jupiter-like exoplanets found in terms of mass and semi-major axis.

Upsilon Andromedae e
An artist's impression of Ups And E
Discovery
Discovered byCuriel et al.
Discovery siteBaja California
Discovery dateNovember 22, 2010 (announced)
December 2, 2010 (published)
Doppler spectroscopy
Orbital characteristics
Apastron5.2738 ± 0.0029 AU (788,950,000 ± 430,000 km)
Periastron5.2175 ± 0.003 AU (780,530,000 ± 450,000 km)
5.2456 ± 0.00067 AU (784,731,000 ± 100,000 km)[1]
Eccentricity0.0055±0.0004[2]
3848.86±0.74[2] d
~10.53946[2] y
367.3 ± 2.3[1]
StarUpsilon Andromedae

    Discovery

    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 other year so far during the exoplanet era has more than one fourth planet been discovered.

    Astronomers originally thought that this planet could not exist because it would have made the planetary system unstable and would have been ejected.[3] But in 2007, an island region of stability was reported where a fourth planet could exist.[4]

    Characteristics

    Upsilon Andromedae e has a mass slightly greater than Jupiter's and orbits at a similar distance as Jupiter from the Sun, at precisely 5.2456 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 takes over a decade to orbit the star. At an eccentricity of 0.00536, the planet's orbit is more circular than that of any of the planets in our solar system[1]. Other authors, while confirming evidence for a fourth planet, challenge the values found, since they use a data set inconsistent with the others.[5]

    Trivia
    • The planet was given the moniker "Ham Sphere" in the Xkcd strip "Exoplanet names" in August, 2013.[6]

    See also
    • HIP 11915 b – another Jupiter analog discovered in 2015

    References
    1. Curiel, S.; et al. (2011). "A fourth planet orbiting υ Andromedae". Astronomy & Astrophysics. 525: A78. Bibcode:2011A&A...525A..78C. doi:10.1051/0004-6361/201015693.
    2. Ligi, R.; et al. (2012). "A new interferometric study of four exoplanet host stars : θ Cygni, 14 Andromedae, υ Andromedae and 42 Draconis". Astronomy & Astrophysics. 545: A5. arXiv:1208.3895. Bibcode:2012A&A...545A...5L. doi:10.1051/0004-6361/201219467.
    3. Ford, Eric B.; et al. (2005). "Planet-planet scattering in the upsilon Andromedae system". Nature. 434 (7035): 873–876. arXiv:astro-ph/0502441. Bibcode:2005Natur.434..873F. doi:10.1038/nature03427. PMID 15829958.
    4. Rory Barnes; Richard Greenberg (2008). "Extrasolar Planet Interactions". arXiv:0801.3226v1 [astro-ph].
    5. Deitrick, R.; et al. (January 2015). "The Three-dimensional Architecture of the υ Andromedae Planetary System". The Astrophysical Journal. 798 (1). arXiv:1411.1059. Bibcode:2015ApJ...798...46D. doi:10.1088/0004-637X/798/1/46.
    6. "Exoplanet Names".
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