From the light curves of Long Period Variables to their evolution along the AGB

TL;DR

This study analyzes light curves of 116 Long Period Variables to uncover how their properties relate to their evolutionary stages along the AGB, revealing new correlations and classifications.

Contribution

It introduces a detailed parameterization of light curves and links specific light curve features to the stars' evolutionary status and dredge-up events.

Findings

A key parameter correlates with the star's AGB evolution.

Two distinct light curve types are identified for stars with dredge-up events.

Evolutionary paths are linked to changes in light curve width and shape.

Abstract

A sample of 116 Long Period Variables is studied with the aim to reveal relations between the properties of their light curves and of their evolution along the Asymptotic Giant Branch (AGB). Each light curve is carefully scrutinized and its properties are summarized in a set of five parameters. One of these, which measures the relative width of the light maxima and minima, is found to be particularly efficient at revealing significant correlations with the current state of the star on the AGB. The picture that had been sketched in an earlier work is clarified and new features are revealed. In particular, the evolution on the AGB of stars having not yet experienced a third dredge-up event is shown to go together with a closely related path followed by the light curve in the parameter space. Moreover, evidence is found for the existence of two different types of light curves for stars having experienced dredge-up events strong enough for their impact to be detectable. For some, probably associated with higher initial mass stars, the light maximum becomes broader as the star evolves along the AGB, while for others it becomes narrower. Interpretations are proposed, however often too speculative to be firmly ascertained: the results presented raise several unanswered questions and point to the need for new observations and analyses, suggesting that light curves still carry more messages and information than has been currently possible to decrypt.