The Most Spherical Natural Object Ever Measured
It is the star KIC 11145123, whose polar radius differs from the equatorial one by only 1.8 parts out of 1 million
“To our knowledge, KIC 11145123 is the most spherical natural object ever measured, more spherical than the quiet Sun.”
This surprising claim is contained in a study published on November 16, 2016, in Science Advances, authored by Laurent Gizon of the Max-Planck-Institut für Sonnensystemforschung in Göttingen, Germany, and eight other authors.
KIC 11145123 is a bright A-type star, 4,000 light-years away from Earth. It is a more evolved star than the Sun. In fact, it has almost reached the end of the central part of its life. According to the calculations of Gizon and colleagues, less than 5% of hydrogen remains in the star core, so the fuel that feeds nuclear fusion reactions during the so-called main sequence is almost finished. KIC 11145123 is hotter than the Sun, with effective temperature of 8,050 K against 5,772 K of our star. It is also much larger (2.24 solar radii) and more massive (1.46 solar masses). However, it rotates four times slower than the Sun, taking 100 days for a full rotation at the equator, while our star takes just over 25…
