47 Ursae Majoris c

Planetbox begin
name = 47 Ursae Majoris cPlanetbox star
star = 47 Ursae Majoris
constell = Ursa Major
RA = RA|10|59|28.0
DEC = DEC|+40|25|49
dist_ly = 45.9
dist_pc = 14.1
class = G1VPlanetbox orbit
semimajor = 3.39cite web|url=http://exoplanets.org/planets.shtml|title=Planets Table|work=Catalog of Nearby Exoplanets|accessdate=2008-10-04]
eccentricity = 0.220 ± 0.028
period = 2190 ± 460
long_peri = 180 ± 170
t_peri = 2,451,581 ± 40
semi-amp = 7.0 ± 2.3Planetbox character
mass = >0.460 Planetbox discovery
discovery_date = 15 August 2001
19 March 2002 (confirmed)
discoverers = Fischer,
Butler, and
Marcy "et al."
discovery_site = flag|United States
discovery_method = Doppler spectroscopy
discovery_status = Existence confirmed,
parameters uncertain

47 Ursae Majoris c is an extrasolar planet approximately 46 light-years away in the constellation of Ursa Major. The planet was discovered located in a long-period around the star 47 Ursae Majoris. It is currently the outermost known planet in its planetary system. Its orbit last 6 years and have a mass at least 0.46 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.cite journal | url=http://www.journals.uchicago.edu/doi/full/10.1086/324336 | author=Fischer, D. et al. | title=A Second Planet Orbiting 47 Ursae Majoris | journal=The Astrophysical Journal | volume=564 |issue=2 | year=2002 | pages=1028 – 1034 | doi=10.1086/324336]

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". [cite journal|url=http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?2004A%26A...414..351N&db_key=AST&nosetcookie=1|author=Naef, D. et al.|title=The ELODIE survey for northern extra-solar planets. III. Three planetary candidates detected with ELODIE|journal=Astronomy and Astrophysics|volume=414|pages=351 – 359|year=2004|doi=10.1051/0004-6361:20034091] A more recent study with datasets spanning over 6900 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. The best solution gives a period of 7586 days (almost 21 years), which would place the planet at 7.73 AU from the star. The parameters are still highly uncertain.cite journal|url=http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?2007ApJ...654..625W&db_key=AST&nosetcookie=1|author=Wittenmyer, R. A., Endl, M., Cochran, W. D.|title=Long-Period Objects in the Extrasolar Planetary Systems 47 Ursae Majoris and 14 Herculis|journal=The Astrophysical Journal|volume=654|issue=1|pages=625 – 632|year=2007|doi=10.1086/509110] The Catalog of Nearby Exoplanets gives an orbital period of 2190 days, however the reference it uses is Fischer "et al." (2002), which does not support this assertion. Nevertheless, these parameters have also been adopted by the Extrasolar Planets Encyclopaedia. [cite web |url=http://exoplanet.eu/planet.php?p1=47+Uma&p2=c |title=Notes for planet 47 UMa c |accessdate=2008-10-04|author=Schneider, J.|work=The Extrasolar Planets Encyclopaedia]

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 b
*47 Ursae Majoris in fiction

References

External links

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