Explaining the Praesepe blue straggler HD 73666

TL;DR

This paper investigates the formation of the blue straggler HD 73666 in Praesepe, concluding it was likely formed by a stellar collision involving a binary system within the last few hundred million years.

Contribution

It provides a detailed analysis of HD 73666's properties and suggests a specific formation scenario through stellar collision, refining understanding of blue straggler origins.

Findings

HD 73666 shows no signs of binarity or mass transfer.

The star's properties suggest a collision origin within 5-350 Myr.

It is a slow rotator with normal abundances.

Abstract

The blue straggler phenomenon is not yet well explained by current theory; however, evolutionary models of star clusters call for a good knowledge of it. Here we try to understand the possible formation scenario of HD 73666, a blue straggler member of the Praesepe cluster. We compile the known physical properties of HD 73666 found in the literature, focusing in particular on possible binarity and the abundance pattern. HD 73666 appears to be slowly rotating, has no detectable magnetic field, and has normal abundances, thereby excluding close binary evolution and mass transfer processes. There is no evidence of a hot radiation source. With the use of theoretical results on blue straggler formation present in literature, we are able to conclude that HD 73666 was probably formed by physical collision involving at least one binary system, between 5 and 350 Myr (50 Myr if the star is an intrinsic slow rotator) ago.