Evidence for rotation-induced mixing in evolved intermediate mass stars

TL;DR

This paper provides observational evidence that rotation-induced mixing significantly affects the internal composition of evolved intermediate mass stars, with a clear correlation between stellar mass and nitrogen-to-carbon ratios.

Contribution

It presents the first observational correlation between stellar mass and [N/C] ratio, supporting the role of rotation-induced mixing in stellar evolution models.

Findings

Different efficiencies of internal mixing observed in stars

Correlation between stellar mass and [N/C] ratio found

Supports rotation-induced mixing as a key process

Abstract

Many observational results seem to indicate more efficient mixing processes in intermediate mass stars (5-20 M$_{\odot}$) than the expected by the standard models. These processes are usually thought to be caused by stellar rotation. Our recent analysis of 19 evolved intermediate mass stars has found them to display different efficiencies of internal mixing. The comparison of these results, and others from the literature, with rotating and non-rotating stellar evolutionary models led us to find, for the first time, an important correlation between stellar mass and the [N/C] ratio; the kind of correlation expected to be produced by a rotation-induced mixing.