Tycho's supernova: the view from {\it Gaia}

TL;DR

This paper uses Gaia DR2 data to analyze candidate stars near Tycho's supernova remnant, aiming to identify a potential surviving companion by examining their kinematics, distances, and orbits with unprecedented accuracy.

Contribution

It provides a comprehensive reevaluation of candidate stars using Gaia DR2 data, improving distance and proper motion measurements for identifying the supernova's companion.

Findings

Gaia DR2 data refines distances and proper motions of candidate stars.

Galactic orbit analysis narrows down potential surviving companions.

Reassessment of previous candidate stars based on new astrometric data.

Abstract

SN 1572 (Tycho Brahe's supernova) clearly belongs to the Ia (thermonuclear) type. It was produced by the explosion of a white dwarf in a binary system. Its remnant has been the first of this type to be explored in search of a possible surviving companion, the mass donor that brought the white dwarf to the point of explosion. A high peculiar motion with respect to the stars at the same location in the Galaxy, mainly due to the orbital velocity at the time of the explosion, is a basic criterion for the detection of such companions. Radial velocities from the spectra of the stars close to the geometrical center of Tycho's supernova remnant, plus proper motions of the same stars, obtained by astrometry with the {\it Hubble Space Telescope}, have been used so far. In addition, a detailed chemical analysis of the atmospheres of a sample of candidate stars had been made. However, the distances to the stars, remained uncertain. Now, the Second {\it Gaia} Data Release (DR2) provides unprecedent accurate distances and new proper motions for the stars can be compared with those made from the {\it HST}. We consider the Galactic orbits that the candidate stars to SN companion would have in the future. We do this to explore kinematic peculiarity. We also locate a representative sample of candidate stars in the Toomre diagram. Using the new data, we reevaluate here the status of the candidates suggested thus far, as well as the larger sample of the stars seen in the central region of the remnant.