- Published on 23 November 2015
In section 10. Planets and planetary systems
The HARPS-N Rocky Planet Search. I. A transiting rocky planet in a 4 planet system at 6.5 pc from the Sun
HD 219134 is a star that is about to become famous. Until now, this small star (about 0.8 solar masses), just visible to the naked eye, had only one distinguishing feature: a mere 6.5 parsecs away from us, it is one of our 150 or so closest neighbours. Motalebi et al., however, found it to have a characteristic that is unique amongst our immediate neighbours, a rocky transiting planet. This planet, HD 219134 b, orbits the star every three days, has 4.5 times the mass of the Earth, 1.7 times the radius of the Earth, and therefore a mean density of 5.9 g/cm3 typical of a rocky composition. The system contains three other planets, with minimum masses between 2.7 and 61 Earth masses and orbital periods between 6.8 and 1200 days. The proximity of the system and the brightness of its star will enable detailed characterization of this system, its dynamics, composition, and formation.