Stellar flybies within 1 ly from the Sun and stars passing through the Hills cloud

Abstract

We reexamine the SIMBAD database with incorporated Gaia DR3 parallaxes and proper motions. Appropriate query searches allow us to find several nearby stars with measured radial velocities having flybies within 1 ly from the Sun (in linear approximation). The closest past flyby \(\approx 215.7\) kyr ago at \(\approx 0.136\) pc is attributed to the star UCAC4 323-037188, currently located at 21.74 pc from the Sun. If the radial velocity of a star is unknown, we attribute to it an ``advantageous'' value of \(\pm 50\) km/s. It allows us to create an additional list of ``Nemesis candidates'' for the perforation of the inner Oort cloud. The closest potential flyby at \(\approx 0.015\) pc (\(\approx\) 0.050 ly \(\approx\) 3147 AU) from the Sun is attributed to GALEX J013712.5-012958 (Gaia DR3 2508809660245711360). It is currently located at the distance of about 111.1 pc and belongs to the Pisces-Eridanus stream. Also, close flybies of some massive bright stars (Algol, A-giant HD 107914, A-subgiant HD 2733 and B-subgiant HD 165704) are analyzed. Finally, we notice that B1-star BD+60 596, whose proper motions and radial velocity are both small, can be considered as the Sun's pseudo-stream companion.