Be star surveys with CCD photometry. II. NGC 1818 and its neighbouring cluster in the LMC

TL;DR

This study surveys Be stars in NGC 1818 and a neighboring cluster in the LMC, revealing higher Be star fractions in these young clusters compared to the field, and compares these findings with Galactic clusters.

Contribution

It provides new photometric data and analysis of Be star populations in two Magellanic Cloud clusters, enhancing understanding of Be star distribution and evolution.

Findings

Higher Be star fraction in both clusters compared to the surrounding field.

The neighboring cluster lacks evolved stars and has a less populated main sequence.

Comparison suggests environmental factors influence Be star occurrence.

Abstract

As part of an ongoing photometric survey of young Magellanic Cloud clusters we identified Be stars in NGC 1818 and a nearby smaller cluster in the Large Magellanic Cloud. The neighbouring cluster does not contain evolved stars, and its sparsely populated main sequence does not extend to stars as massive as in NGC 1818. Both clusters are younger than the surrounding field population and contain a much higher Be star fraction. We present a table with photometry, astrometric positions, and IAU-conform identifiers of the Be stars. We compare Be star fractions in Magellanic Cloud clusters and Galactic open clusters and discuss possible constraints on Be star theories.