WASP-15b
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WASP-15b is an extrasolar planet discovered in 2008. This planet orbits about one-twentieth that of Earth’s distance from the Sun. This planet takes a little over 1% of Earth’s year to go around the star WASP-15. The mass of this planet is about one half that of Jupiter but its radius is nearly 50% larger than Jupiter, making the density of this planet only one quarter that of water.[1]
Discovery
WASP-15 was first observed by the WASP-South branch of the SuperWASP project, which operates from the South African Astronomical Observatory, between May 4, 2006 and July 17, 2006. It was later observed by both WASP-South and SuperWASP-North, which is based in the Canary Islands, from January 31, 2007 to July 17, 2007 and from January 31, 2008 to May 29, 2008.[1] Further analysis taken from 24,943 collected data points revealed eleven full or partial transits.[1]
Follow-up observations were conducted by a European and American science team at the 1.2m Leonhard Euler Telescope at La Silla Observatory in Chile, which further raised the possibility of the existence of a planet in WASP-15's orbit; use of the CORALIE spectrograph on the Euler Telescope between March 6, 2008 and July 17, 2008 revealed that the variations in radial velocity measurements were not because of an eclipsing binary star system.[1]
CORALIE and the High Resolution Echelle Spectrometer (HIRES) revealed the spectrum of WASP-15, which was used to derive the star's characteristics.[1] The science team studying WASP-15 found that, after running best-fit models, WASP-15's radial velocity and transit shifts are most likely due to the existence of a planet.[1]
WASP-15's planet, WASP-15b, had one of the lowest densities known amongst extrasolar planets when it was discovered. Its discovery paper was published by the American Astronomical Society on April 29, 2009 in the Astronomical Journal.[1]
Host star
WASP-15 is an F-type star located in the Hydra constellation. It is located approximately 308 parsecs (1,004 light years) from Earth and has an apparent magnitude of 10.9, making it invisible to the unaided eye. The star is 1.18 times more massive than the Sun, and has a radius that is 1.477 times larger than that of the Sun, making it more diffuse. WASP-15 has an effective temperature of 6300 K, and is thus hotter than the Sun, although at 3.9 billion years, it is also younger. WASP-15 has a metallicity of [Fe/H] of -0.17, which means that it has 68% of the iron found in the Sun.[2]
See also
References
- ^ a b c d e f g West; Anderson, D. R.; Gillon, M.; Hebb, L.; Hellier, C.; Maxted, P. F. L.; Queloz, D.; Smalley, B.; Triaud, A. H. M. J.; et al. (2009). "THE LOW DENSITY TRANSITING EXOPLANET WASP-15b". The Astronomical Journal. 137: 4834–4836. Bibcode:2009AJ....137.4834W. doi:10.1088/0004-6256/137/6/4834.
{{cite journal}}: Explicit use of et al. in:|author=(help) - ^ Jean Schneider (2010). "Notes for star WASP-15". Extrasolar Planets Encyclopaedia. Retrieved 13 May 2011.
External links
Media related to WASP-15b at Wikimedia Commons
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