Title: Mass, Density, and Formation Constraints in the Compact, Sub-Earth Kepler-444 System including Two Mars-Mass Planets Author: Sean M. Mills, Daniel C. Fabrycky
Kepler-444 is a five planet system around a host-star approximately 11 billion years old. The five transiting planets all have sub-Earth radii and are in a compact configuration with orbital periods between 3 and 10 days. Here we present a transit-timing analysis of the system using the full Kepler data set in order to determine the masses of the planets. Two planets, Kepler-444 d (M_d=0.036^{+0.065}_{-0.020} earth masses) and Kepler-444 e (M_e=0.034^{+0.059}_{-0.019} earth masses), have confidently detected masses due to their proximity to resonance which creates transit timing variations. The mass ratio of these planets combined with the magnitude of possible star-planet tidal effects suggests that smooth disk migration over a significant distance is unlikely to have brought the system to its currently observed orbital architecture without significant post-formation perturbations.
The tightly packed system is home to five planets that range in size, the smallest comparable to the size of Mercury and the largest to Venus. All five planets orbit their sun-like star in less than ten days, which makes their orbits much closer than Mercury's sweltering 88-day orbit around the sun. Read more
An ancient solar system similar to our own has been discovered by scientists. Studying data from the Kepler telescope, the team, led by the University of Birmingham, found a star orbited by five planets similar in size to Earth. Read more
Astronomers have found a star system that bears striking resemblance to our inner solar system. It's a sun-like star that plays host to a system of five small exoplanets - from the size of Mercury to the size of Venus. But there's something very alien about this compact 'solar system'; it formed when the universe was only 20 percent the age it is now, making making it the most ancient star system playing host to terrestrial sized worlds discovered to date. Read more