The OGLE Collection of Variable Stars. Over 15 000 Delta Scuti Stars in the Large Magellanic Cloud

TL;DR

This paper presents the largest collection of extragalactic delta Scuti stars from the OGLE project, including new binary candidates and detailed period-luminosity relations, advancing understanding of variable stars in the Large Magellanic Cloud.

Contribution

It provides the first extensive dataset of delta Scuti stars in the LMC, including binary candidates and refined period-luminosity relations, with implications for stellar evolution and distance measurements.

Findings

Largest sample of extragalactic delta Sct stars published

First candidates for binary systems with delta Sct components beyond the Milky Way

Identification of a non-linear period-luminosity relation with a break at 0.5 days

Abstract

We present the OGLE collection of delta Scuti stars in the Large Magellanic Cloud and in its foreground. Our dataset encompasses a total of 15 256 objects, constituting the largest sample of extragalactic delta Sct stars published so far. In the case of 12 delta Sct pulsators, we detected additional eclipsing or ellipsoidal variations in their light curves. These are the first known candidates for binary systems containing delta Sct components beyond the Milky Way. We provide observational parameters for all variables, including pulsation periods, mean magnitudes, amplitudes, and Fourier coefficients, as well as long-term light curves in the I- and V-bands collected during the fourth phase of the OGLE project. We construct the period-luminosity (PL) diagram, in which fundamental-mode and first-overtone delta Sct stars form two nearly parallel ridges. The latter ridge is an extension of the PL relation obeyed by first-overtone classical Cepheids. The slopes of the PL relations for delta Sct variables are steeper than those for classical Cepheids, indicating that the continuous PL relation for first-overtone delta Sct variables and Cepheids is non-linear, exhibiting a break at a period of approximately 0.5 d. We also report the enhancement of the OGLE collection of Cepheids and RR Lyr stars with newly identified and reclassified objects, including pulsators contained in the recently published Gaia DR3 catalog of variable stars. As a by-product, we estimate the contamination rate in the Gaia DR3 catalogs of Cepheids and RR Lyr variables.