The OGLE Collection of Variable Over. Stars 15 000 δ Scuti Stars in the Large Magellanic Cloud
I. Soszyński1, P. Pietrukowicz1, A. Udalski1, J. Skowron1, M.K. Szymański1, R. Poleski1, D.M. Skowron1, S. Kozłowski1, P. Mróz1, P. Iwanek1, M. Wrona1, K. Ulaczyk2,1, K. Rybicki3.1, M. Gromadzki1 and M. Mróz1 1Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warszawa, Poland 2Department of Physics, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK 3Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot 76100, Israel
Received: September 26, 2023
ABSTRACT
We present the OGLE collection of δ 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 δ Sct stars published so far. In the
case of 12 δ Sct pulsators, we detected additional eclipsing
or ellipsoidal variations in their light curves. These are the first
known candidates for binary systems containing δ 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 δ 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 δ Sct variables are steeper than those for
classical Cepheids, indicating that the continuous PL relation for
first-overtone δ 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.
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