Photometry of two unusual A supergiant systems in the Small Magellanic Cloud

TL;DR

This study analyzes multiwavelength photometry of two unusual variable supergiant stars in the Small Magellanic Cloud, revealing complex periodicities and potential binary interactions.

Contribution

It provides detailed long-term photometric data and interprets the variability as evidence of wide-orbit binaries and stellar pulsations.

Findings

SMC-SC3 exhibits a 238.1-day primary period with ellipsoidal variability.

SMC-SC4 shows modulated eclipses indicating binary interaction.

Secondary variability in SMC-SC3 suggests nonradial pulsations.

Abstract

We present multiwavelength broadband photometry and V, I time resolved photometry for two variable bright stars in the SMC, OGLE004336.91-732637.7 (SMC-SC3) and OGLE004633.76-731204.3 (SMC-SC4). The light curves span 12 years and show long-term periodicities (SMC-SC3) and modulated eclipses (SMC-SC4) that are discussed in terms of wide-orbit intermediate mass interacting binaries and associated envelopes. SMC-SC3 shows a primary period of 238.1 days along with a complicated waveform suggesting ellipsoidal variablity influenced by an eccentric orbit. This star also shows a secondary variability with an unstable periodicity that has a mean value of 15.3 days. We suggest this could be associated with nonradial pulsations.