Notably, Kapteyn's star
is about 11 billion years old and probably stolen from a dwarf galaxy.
Dr Guillem Anglada-Escude, from QMUL's School of Physics and Astronomy said that it was astounding finding those planets orbiting Kapteyn's star
, although previous data did show some moderate excess of variability, so they were looking for very short period planets when the new signals showed up loud and clear.
Hipparcos 24186 is perhaps better known as Kapteyn's Star, a lovely, ruddy-hued type M1 magnitude 8.8 sub-dwarf only 12.8 light years away.
The galaxy NGC 1930, situated another 2.7 degrees further south from Kapteyn's Star, is a somewhat faint object.
At 8 arcseconds per year, Kapteyn's Star moves across the sky at a fast clip, covering the diameter of a full Moon every 225 years.
Currently, Kapteyn's Star is only 12.7 light-years away; it could be the remnant of a tidally stripped galaxy whose surviving core might be the globular cluster Omega Centauri.
But the object's parallax is small compared with its proper motion: the object traverses 8.1 arcseconds per year, the third largest proper motion of any object outside the solar system (trailing only Barnard's Star and Kapteyn's Star
(Curiously, Kapteyn's Star
receives similar treatment but the far better known Barnard's Star--the star with the largest proper motion--does not, and it cannot be reliably identified at the telescope using the book's chart for Ophiuchus.) Tirion also very cleanly illustrates, in the book's introduction, the concepts of parallax, the zodiac, precession, and proper motion.