Alpha Centauri Color

Asteroseismic studies, chromospheric activity, and stellar rotation (gyrochronology) are all consistent with the Alpha Centauri system being similar in age to, or slightly older than, the Sun. Asteroseismic analyses that incorporate tight observational constraints on the stellar parameters for the Alpha Centauri stars have yielded age estimates of 4. 85±0. 5 Gyr, 5. 0±0. 5 Gyr, 5. 2 ± 1. 9 Gyr, 6. 4 Gyr, and 6. 52±0. 3 Gyr. Age estimates for the stars based on chromospheric activity (Calcium H & K emission) yield 4. 4 ± 2. 1 Gyr, whereas gyrochronology yields 5. 0±0. 3 Gyr. Stellar evolution theory implies both stars are slightly older than the Sun at 5 to 6 billion years, as derived by their mass and spectral characteristics.



The GRAIL mission determined the internal structure of the Moon in great detail for nine months during 2012. Armed with this the new information, GRAIL astronomers were able to redefine the sizes of the largest impact basins on the lunar surface. The scientists also ruled out the possibility that the mysterious features actually exist on Titan's surface in the form of frozen methane rain or icy lava erupted from cryovolcanoes. Such surface features would show a different chemical signature and would be visible for much longer periods of time than the bright features observed in this study. The bright features were visible from time spans of only 11 hours to five weeks. "If there are plumes on Europa, as we now strongly suspect, with the Europa Clipper we will be ready for them," commented Dr. Jim Green in the April 13, 2017 NASA Press Release. Dr. Green is Director of Planetary Science at NASA Headquarters.