and have expanded to great proportions. Although there has been too little observation of their orbit to calculate their masses, comparison with evolutionary calculations suggests that each are about double the mass of the Sun. Originating from the same interstellar cloud some two billion years ago, the stars have iron contents about a third that of the Sun. It is hard to tell how far along they might be in their life cycle. They both may be fusing helium in their cores, or they could be giants in development, with quiet helium cores that are waiting to fire up. The chemical composition at the surface, which is influenced by age, suggests the former. Variability γ Leonis is a suspected variable star, with a visual magnitude range of 1.84 to 2.03. It is not known which of the two components is variable. In 1959, the star was mistakenly published as an eclipsing binary due to a typographical error when referring to Y Leonis. Planetary system On November 6, 2009, the discovery of a planetary companion around primary star γ1 Leonis (γ Leonis A) was announced. The radial velocity measurements suggest two additional periodicities of 8.5 and 1,340 days. The former 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 AU 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. References External links Algieba at Jim Kaler's Stars Astronomical Reference from Author David Darling Leo (constellation) Leonis, Gamma Leonis, 41 Binary stars Planetary systems with one confirmed planet Algieba K-type giants G-type giants 4057 089484 050583 BD+20 2467 Suspected variables