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47 Ursae Majoris c

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47 Ursae Majoris c
Extrasolar planet List of extrasolar planets
47 UMa c 2.png
An artist's conception of 47 Ursae Majoris c.
Parent star
Star 47 Ursae Majoris
Constellation Ursa Major
Right ascension (α) 10h 59m 28.0s
Declination (δ) +40° 25′ 49″
Apparent magnitude (mV) 5.03
Distance 45.9 ly
(14.06 pc)
Spectral type G1V
Mass (m) 1.08 M
Radius (r) 1.172 ± 0.111 R
Temperature (T) 5887 ± 3.8 K
Metallicity [Fe/H] 0.04
Age 6.03 Gyr
Orbital elements
Semimajor axis (a) 3.6 ± 0.1[1] AU
(~540 Gm)
    ~26 mas
Periastron (q) 3.3+0.4
(~490 Gm)
Apastron (Q) 4.0+0.2
(~600 Gm)
Eccentricity (e) 0.098+0.047
Orbital period (P) 2391+100
[1] d
(~6.55 y)
Orbital speed (υ) 16.5+1.1
Argument of
(ω) 295+114
Time of periastron (T0) 2,452,441+628
[1] JD
Semi-amplitude (K) 7.0 ± 2.3[2] m/s
Physical characteristics
Minimum mass (m sin i) 0.540+0.066
[1] MJ
Stellar flux (F) 0.115
Temperature (T) 152
Discovery information
Discovery date 15 August 2001
19 March 2002 (confirmed)
Discoverer(s) Fischer,
Butler, and
Marcy et al.
Discovery method Doppler spectroscopy
Discovery site  United States
Discovery status Confirmed
Other designations
47 UMa c,[3] HD 95128 c[4][note 1]
Database references
Extrasolar Planets
Exoplanet Archive data
Open Exoplanet Catalogue data

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.


Orbits of the 47 Ursae Majoris system planets. 47 UMa c is the middle planet.

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.[5]

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".[6] 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).[7]

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.[1]

Physical characteristics[edit]

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[edit]


  1. ^ These alternative planetary designations are taken from the alternative designations of the host star, and are used in scientific papers occasionally for some exoplanets (see Milone & Wilson 2008 and Raghavan 2009). The most commonly used star designations are Bayer, Flamsteed, HD, HIP, HR, and Gliese.


  1. ^ a b c d e f g P. C. Gregory; D. A. Fischer (2010). "A Bayesian periodogram finds evidence for three planets in 47 Ursae Majoris". Monthly Notices of the Royal Astronomical Society 403 (2): 731. arXiv:1003.5549. Bibcode:2010MNRAS.403..731G. doi:10.1111/j.1365-2966.2009.16233.x. 
  2. ^ "Planets Table". Catalog of Nearby Exoplanets. Archived from the original on 21 September 2008. Retrieved 2008-10-04. 
  3. ^ D. Raghavan (2009). "A Survey of Stellar Families: Multiplicity of Solar-type Stars" (PDF). PhD Thesis (Georgia State University): 224–226. 
  4. ^ E. F. Milone; W. J. F. Wilson (2008). Solar System Astrophysics: Planetary Atmospheres and the Outer Solar. Solar System Astrophysics 2. Springer. pp. xv, 328, 339, 349. ISBN 0-387-73153-9. 
  5. ^ D. A. Fischer et al. (2002). "A Second Planet Orbiting 47 Ursae Majoris". Astrophysical Journal 564 (2): 1028–1034. Bibcode:2002ApJ...564.1028F. doi:10.1086/324336. 
  6. ^ D. Naef et al. (2004). "The ELODIE survey for northern extra-solar planets. III. Three planetary candidates detected with ELODIE". Astronomy and Astrophysics 414: 351–359. arXiv:astro-ph/0310261. Bibcode:2004A&A...414..351N. doi:10.1051/0004-6361:20034091. 
  7. ^ R. A. Wittenmyer; M. Endl; W. D.Cochran (2007). "Long-Period Objects in the Extrasolar Planetary Systems 47 Ursae Majoris and 14 Herculis". Astrophysical Journal 654 (1): 625–632. arXiv:astro-ph/0609117. Bibcode:2007ApJ...654..625W. doi:10.1086/509110. 

External links[edit]

Coordinates: Sky map 10h 59m 28.0s, +40° 25′ 49″