Gamma1 Leonis b
Extrasolar planet List of extrasolar planets
Artist's conception of Gamma Leonis b.
Parent star

<tr> <td colspan="2">Star</td> <td>Gamma Leonis</td></tr><tr> <td colspan="2">Constellation</td> <td>Leo</td></tr><tr> <td>Right ascension</td> <td style="text-align: center">(α)</td> <td>10h 19m 58.3s</td></tr><tr> <td>Declination</td> <td style="text-align: center">(δ)</td> <td>+19° 50′ 30″</td></tr><tr> <td>Apparent magnitude</td> <td style="text-align: center">(mV)</td> <td>2.28</td></tr><tr><td colspan="2">Distance</td><td>125.5 ly
(38.5 pc)</td></tr><tr><td colspan="2">Spectral type</td> <td>K0IIIb</td></tr>

Orbital elements

<tr><td>Semimajor axis</td><td style="text-align: center">(a)</td> <td>1.19[1] AU
(178 Gm)</td></tr><tr> <td>Periastron</td> <td style="text-align: center">(q)</td> <td>1.02 AU
(152 Gm)</td></tr><tr> <td>Apastron</td> <td style="text-align: center">(Q)</td> <td>1.36 AU
(203 Gm)</td></tr><tr> <td>Eccentricity</td> <td style="text-align: center">(e)</td> <td>0.14[1]</td></tr><tr><td>Orbital period</td><td style="text-align: center">(P)</td> <td>429[1] d
(1.17 y)</td></tr><tr> <td>Orbital speed</td> <td style="text-align: center">(υ)</td> <td>30.3 km/s</td></tr>

Physical characteristics

<tr><td>Minimum mass</td><td style="text-align: center">(m sin i)</td><td>8.78[1] MJ</td></tr>

Discovery information

<tr> <td colspan="2">Discovery date</td> <td>November 6, 2009</td></tr><tr> <td colspan="2">Discoverer(s)</td> <td>Inwoo Han et al.[1]</td></tr><tr> <td colspan="2">Discovery method</td> <td>Radial velocity</td></tr><tr> <td colspan="2">Discovery site</td> <td>Template:Country data South Korea</td></tr><tr> <td colspan="2">Discovery status</td> <td>Published</td></tr>

Gamma Leonis b is an extrasolar planet located 125.5 light years away in the constellation Leo, orbiting the giant star Gamma Leonis.[1]


On November 6, 2009, a planetary companion around primary star Gamma1 Leonis has been announced.[1] Moreover radial velocity variations would also hint two strong signals at 8.5 and 1340 days. The former periodicity is likely due to stellar pulsation, whereas the latter could be indicative of the presence of an additional planetary companion with 2.14 Jupiter masses, moderate eccentricity (e=0.13) and located at 2.6 Astronomical Units away from the giant star. Nevertheless the nature of such a signal is still unclear and further investigations are needed to confirm or rule out an additional substellar companion.


The planet has a minimum mass of 8.78 Jupiter masses. The true mass, as with the majority of other extrasolar planets discovered by the radial velocity method, is unknown.


  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Han, Inwoo; Lee, B. C.; Kim, K. M.; Mkrtichian, D. E.; Hatzes, A. P.; Valyavin, G. (2010). Detection of a Planetary Companion around the giant star γ1 Leonis. Astronomy and Astrophysics 509.

Coordinates: Sky map 10h 19m 58.3s, +19° 50′ 30″

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