Ten cool facts about the ancient Kepler-444 stellar system

A paper I worked on with Tiago Campante from the University of Birmingham and many others has just been published. It’s a truly astounding system. Here are 10 cools facts

  1. The star is 11.2 billion years old. The Universe was just 20% of its current age when this star formed.
  2. The star is just 36 parsec away. It is in our stellar backyard.
  3. The star is a high proper motion star. The star moves at half an arcsecond a year.
  4. The star is a thick disk star. It is part of an older region in our galaxy.
  5. The star is the densest where we have measured seismic oscillations. We used these oscillations to measure the star’s age and density.
  6. Five sub-earth-sized planets orbit the star. This system hosts a planet almost as small as Kepler-37b.
  7. The planets all have orbital periods of less than 10 days. This is the most compact planetary system.
  8. These planets are the oldest know terrestrial planets. Only the giant planets around Kapteyn’s Star are older.
  9. These planets must have been formed from a Type 1bc or II supernovae material, not Type Ia. Type Ia supernovae are caused by white dwarfs and white dwarfs were not abundant in the early galaxy.
  10. The orbital periods of the planets are all very close to mutuals resonances. The orbital period ratios of the five planets are 125:100:75:60:48. i.e. for every 125 orbits of the inner planet, the outer planet orbits 48 times.


The paper is available from http://arxiv.org/abs/1501.06227.

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