The Thermal Pulses of Very-Low-Mass Stars

TL;DR

Very-low-mass stars experience thermal pulses late in their evolution, causing significant luminosity and temperature changes, which could produce observable phenomena in binary systems within a cosmologically relevant timeframe.

Contribution

This paper explores the thermal pulses of very-low-mass stars, highlighting their potential observability and implications for binary star evolution.

Findings

Very-low-mass stars develop hydrogen-shell flashes late in their evolution.

These flashes cause strong luminosity and temperature variations.

Binary systems can produce observable flashes within a Hubble time.

Abstract

Very-low-mass stars can develop secularly unstable hydrogen-burning shells late in their life. Since the thermal pulses that go along are driven at the bottoms of very shallow envelopes, the stars' luminosities and effective temperatures react strongly during a pulse cycle. Towards the end of the Galaxy's stelliferous era, the hydrogen-shell flashing very-low-mass single stars should inflict an intricate light-show performed by the large population of previously inconspicuous dim stars. Unfortunately, this natural spectacle will discharge too late for mankind to indulge in. Not all is hopeless, though: In the case of close binary-star evolution, hydrogen-shell flashes of mass-stripped, very-low mass binary components can develop in a fraction of a Hubble time. Therefore, the Galaxy should be able put forth a few candidates that are going to evolve through a H-shell flash in a humanity-compatible time frame.