47 Ursae Majoris c
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| Extrasolar planet | List of extrasolar planets | |
|---|---|---|
| Parent star | ||
| Star | 47 Ursae Majoris | |
| Constellation | Ursa Major | |
| Right ascension | (α) | 10h 59m 28.0s |
| Declination | (δ) | +40° 25′ 49″ |
| Distance | 45.9 ly (14.1 pc) | |
| Spectral type | G1V | |
| Orbital elements | ||
| Semimajor axis | (a) | 3.39 AU |
| Eccentricity | (e) | 0.220 ± 0.028 |
| Orbital period | (P) | 2190 ± 460 d |
| Angular distance | (θ) | 240 mas |
| Longitude of periastron |
(ω) | 180 ± 170° |
| Time of periastron | (T0) | 2,451,581 ± 40 JD |
| Semi-amplitude | (K) | 7.0 ± 2.3 m/s |
| Physical characteristics | ||
| Mass | (m) | >0.460 MJ |
| Discovery information | ||
| Discovery date | August 15, 2001 announced March 19, 2002 |
|
| Discoverer(s) | Fischer, Butler, Marcy, et al. |
|
| Detection method | Doppler spectroscopy | |
| Discovery site | California, United States | |
| Discovery status | Confirmed | |
47 Ursae Majoris c is an extrasolar planet orbiting the Sun-like star 47 Ursae Majoris. It is 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.
Contents |
[edit] 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.[1]
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".[2] 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.[3] However, the parameter of this planet is now confirmed, at an orbital distance of 3.39 ± 0.36 AU and a period of 2190 ± 460 days or 6 years.
[edit] 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.
[edit] References
- ^ Fischer, D. et al. (2002). "A Second Planet Orbiting 47 Ursae Majoris". The Astrophysical Journal 564 (2): 1028 – 1034. doi:.
- ^ Naef, D. et al. (2004). "The ELODIE survey for northern extra-solar planets. III. Three planetary candidates detected with ELODIE". Astronomy and Astrophysics 414: 351 – 359. doi:.
- ^ Wittenmyer, R. A., Endl, M., Cochran, W. D. (2007). "Long-Period Objects in the Extrasolar Planetary Systems 47 Ursae Majoris and 14 Herculis". The Astrophysical Journal 654 (1): 625 – 632. doi:.
