47 Ursae Majoris c

47 Ursae Majoris c (sometimes abbreviated 47 Uma c) is an extrasolar planet approximately 46 light-years from Earth in the constellation of Ursa Major. The planet was discovered located in a long-period around the star 47 Ursae Majoris. Its orbit lasts 6.55 years and the planet has a mass at least 0.540 times that of Jupiter.
==Discovery==
Like the majority of known extrasolar planets, 47 Ursae Majoris c was discovered by detecting changes in its star's radial velocity caused by the planet's gravity. This was done by measuring the Doppler shift of the star's spectrum.
At the time of discovery in 2001, 47 Ursae Majoris was already known to host one extrasolar planet, designated 47 Ursae Majoris b. Further measurements of the radial velocity revealed another periodicity in the data unaccounted for by the first planet. This periodicity could be explained by assuming that a second planet, designated 47 Ursae Majoris c, existed in the system with an orbital period close to 7 years. Observations of the photosphere of 47 Ursae Majoris suggested that the periodicity could not be explained by stellar activity, making the planet interpretation more likely. The planet was announced in 2002.
Further measurements of 47 Ursae Majoris failed to detect the planet, calling its existence into question. Furthermore, it was noted that the data used to determine its existence left the planet's parameters "almost unconstrained".
 A more recent study with datasets spanning over 6,900 days came to the conclusion that while the existence of a second planet in the system is likely, periods around 2,500 days have high false-alarm probabilities, and gave a best-fit period of 7,586 days (almost 21 years).
In 2010, a study was published that determined that there are three giant planets orbiting 47 Ursae Majoris, including one at 2,391 days that corresponds well with the original claims for 47 Ursae Majoris c.
==Physical characteristics==
Since 47 Ursae Majoris c was detected indirectly, properties such as its radius, composition, and temperature are unknown. Based on its high mass, the planet is likely to be a gas giant with no solid surface.
==See also==
*47 Ursae Majoris in fiction
==Footnotes==
==References==
==External links==
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Category:47 Ursae Majoris
Category:Exoplanets discovered in 2001
Category:Gas giants
Category:Exoplanets detected by radial velocity