Variability of Ha emission in young stellar objects in the cluster IC 348

TL;DR

This study investigates the variability of H-alpha emission in young stellar objects within the IC 348 cluster, revealing significant activity differences related to evolutionary stage, mass, and binarity, with implications for star formation and accretion processes.

Contribution

It provides the first detailed analysis of H-alpha variability in IC 348, linking emission changes to stellar activity, mass, and binarity, and comparing variability across evolutionary stages.

Findings

90 out of 127 stars show significant H-alpha variability.

Variables are more massive and active than non-variables.

Some stars change their evolutionary classification due to binarity.

Abstract

The aim of this work is to identify and study the stellar objects with variable EW(Ha) in the young stellar cluster IC 348. We performed photometric and slit-less observations at several epochs in order to reveal the variable objects. Significant variability of EW(Ha) was found in 90 out of 127 examined stars. From all epochs of observations, 32 objects were classified as CTT and 69 as WTT objects. The fraction of the variables in these samples is about 60%. We also identified 20 stellar objects, which showed not only a significant variability of the equivalent width, but which also change their apparent evolutionary stage. The analysis of data obtained over a wide wavelength range (from X-ray to mid-infrared) has shown that Ha activity and the measure of its variability are in good agreement with the activity of stellar objects measured with its other parameters, such as X-ray radiation and the mass accretion rate. The EW(Ha) differs not only between objects at different evolutionary stages, but also between variable and non-variable objects. The variables in the CTT and WTT samples are more active than non-variables although they have almost the same evolutionary age. Another distinct difference between these variables and non-variables is their average masses. The variables from both CTT and WTT samples are noticeably more massive than non-variables. Our data confirm the assumption made for other star formation regions, that the decay of accretion activity occurs more slowly for more massive CTT objects. Apparently, a similar trend is also present in WTT objects, which are at a later stage of evolution. The variability of the stellar objects, which change their evolutionary classes, at least in a fraction of them, is due to the fact that they are close binaries, which affects and modulates their Ha emission activity.