Astronomers from the Astronomical Observatory of the University of Warsaw (UW) have explained almost a century-old mystery of the origin of the so-called long secondary period in stellar red giants. They published an article on this topic in The Astrophysical Journal Letters.

Scientists from the Astronomical Observatory of the University of Warsaw under the supervision of Prof. Igor Soszyński have been studying the phenomenon of the so-called Long Secondary Period (LSP), using the world’s largest photometric database created for almost 30 years by the Sky Survey Optical Gravitational Lensing Experiment (OGLE).  The OGLE project conducts regular observations of about 2 billion stars belonging to our Galaxy and the nearby Magellanic Clouds. It is chaired by Prof. Andrzej Udalski. The huge OGLE database was used to select an unprecedentedly large sample of around 16,000 LSP stars and study their properties.

Measurements of changes in the radial velocity of LSP stars indicate that the companions of red giants, immersed in a dust cloud are most often bodies with substellar masses, the so-called brown dwarfs. Objects of this type probably arose as a result of the pulling of matter by planets orbiting initially in distant orbits around their stars. This explanation opens up new perspectives for studying the spatial distributions of planetary systems in our galaxies and other galaxies.

More:
https://iopscience.iop.org/article/10.3847/2041-8213/abf3c9