Examination of the Relationship Between Spectral Type and Stellar Rotational Velocity in $\sim$50,000 Single Stars

TL;DR

This study analyzes the relationship between spectral type and stellar rotational velocity in about 50,000 single stars, revealing a significant decline in rotation speed from early to late spectral types and with stellar evolution.

Contribution

It provides a comprehensive analysis of how stellar spectral type and evolutionary stage influence rotational velocities across a large stellar sample.

Findings

Significant decrease in mean vsini from early to late spectral types.

Approximately 100 km/s reduction in vsini between hot and cool stars.

Greater reduction in vsini observed in stars beyond the subgiant phase.

Abstract

In this study, we present the results of the relationship between spectral type (ST) and the projected stellar rotational velocity ($vsini$), utilising a sample of approximately 50,000 single stars across a range of evolutionary stages. The STs of the stars included in this study span a broad range, from O0 to M9. We examine the stars in our data set, which has been divided into two groups according to ST and luminosity class (LC). The groups were conducted an investigation into the relationship between the mean $vsini$ ($\langle vsini \rangle$) and STs, as well as the dependence of $\langle vsini \rangle$ on STs and LCs. The rationale for investigating the two subgroups separately is to take into account for the evolutionary status of the stars and ascertain the impact on stellar rotation. The results demonstrate a notable decline in $\langle vsini \rangle$ as the spectral type progresses from early to late types. In particular, we found a significant decrease in $\langle vsini \rangle$ values, amounting to approximately 100 km/s, between hot stars (STs O0 to F2) and cool stars (STs F2 to M9). Moreover, a reduction in $\langle vsini \rangle$ is discernible as stars evolve, with this trend being most pronounced in evolutionary stages beyond the subgiant phase.