Optical spectroscopy of Classical Be stars in open clusters

TL;DR

This study provides a comprehensive spectroscopic analysis of 150 Classical Be stars in open clusters, revealing their spectral characteristics, variability, and prevalence of Fe II lines, with a significant portion studied for the first time.

Contribution

It offers the first detailed spectral characterization of a large sample of CBe stars across various cluster environments, including new observations of previously unstudied stars.

Findings

86% of CBe stars show Fe II lines.

80% of stars have H-alpha equivalent width between -1 and -40 Å.

Detected short and long-term line profile variability.

Abstract

We present a spectroscopic study of 150 Classical Be stars in 39 open clusters using medium resolution spectra in the wavelength range 3800 - 9000 \AA. One-third of the sample (48 stars in 18 clusters) has been studied for the first time. All these candidates were identified from an extensive survey of emission stars in young open clusters using slitless spectroscopy (Mathew et al. 2008). This large data set covers CBe stars of various spectral types and ages found in different cluster environments in largely northern open clusters, and is used to study the spectral characteristics of CBe stars in cluster environments. About 80% of CBe stars in our sample have H-alpha equivalent width in the range -1 to -40 \AA. About 86% of the surveyed CBe stars show Fe II lines. The prominent Fe II lines in our surveyed stars are 4584, 5018, 5169, 5316, 6318, 6384, 7513 and 7712 \AA. We have identified short and long-term line profile variability in some candidate stars through repeated observations.