HD 219134 b [SEP] constellation
HD 219134 b
HD 219134 b (or HR 8832 b) is one of at least five exoplanets orbiting HR 8832, a main-sequence star in the constellation of Cassiopeia. As of July 2015, super-Earth HD 219134 b, with a size of about 1.6 , and a density of 6.4 g/cm, was reported as the closest rocky exoplanet to the Earth, at 21.25 light-years away. The exoplanet was initially detected by the instrument HARPS-N of the Italian Telescopio Nazionale Galileo via the
(compared to the distance of Mercury from the Sun, which is about 0.38 AU).
Characteristics Atmosphere.
In 2017, it was predicted that HD 219134 b and HD 219134 c likely have atmospheres that are secondary in nature, based on the compositions of the planets and the potential for atmospheric escape. For HD 219134 b, the predicted atmosphere was calculated to reach a height of about 0.18 (~1,150 km), below the predicted height of a primordial hydrogen atmosphere (0.28 ). This would indicate a secondary atmosphere