Tidal Disruption Events from Stripped Stars

TL;DR

This paper investigates the nitrogen enrichment observed in tidal disruption events (TDEs), showing that TDEs from stripped stars in binaries can produce higher N/C ratios and that their abundance ratios evolve predictably over time.

Contribution

It demonstrates that TDEs from binary-stripped stars can explain observed nitrogen enrichment and predicts the time-dependent behavior of N/C ratios in such events.

Findings

Stripped stars in binaries produce higher N/C enhancements in TDEs.

The N/C ratio in TDEs from stripped stars varies inversely with main-sequence stars.

Predicted N/C evolution enables better characterization of disrupted stars.

Abstract

Observations of tidal disruption events (TDEs) show signs of Nitrogen enrichment reminiscent of other astrophysical sources such as active galactic nuclei (AGN) and star-forming galaxies. Given that TDEs probe the gas from a single star, it is possible to test if the observed enrichment is consistent with expectations from the CNO cycle by looking at the observed Nitrogen/Carbon (N/C) abundance ratios. Given that $\approx 20\%$ of solar mass stars (and an even larger fraction of more massive stars) live in close binaries, it is worthwhile to also consider what TDEs from stars influenced by binary evolution would look like. We show here that TDEs from stars stripped of their Hydrogen-rich (and Nitrogen-poor) envelopes through previous binary-induced mass loss can produce much higher observable N/C enhancements than even TDEs from massive stars. Additionally, we predict that the time-dependence of the N/C abundance ratio in the mass fallback rate of stripped stars will follow the inverse behavior of main-sequence stars, enabling a more accurate characterization of the disrupted star.