IRSF/SIRIUS JHKs near-infrared variable star survey in the Magellanic Clouds

TL;DR

This survey used near-infrared observations to identify variable stars in the Magellanic Clouds, revealing infrared variables not detected in optical surveys and analyzing their pulsation properties.

Contribution

The paper presents a large-scale near-infrared variable star survey in the Magellanic Clouds, expanding the catalog of variable red giants and identifying objects missed by optical surveys.

Findings

Detected infrared variables not seen in optical surveys.

Found that some variables do not follow the standard Mira period-Ks relation.

Provided a comprehensive catalog of variable red giants in the Magellanic Clouds.

Abstract

We carried out a NIR variable star survey toward the Large and Small Magellanic Clouds using the InfraRed Survey Facility (IRSF) at Sutherland, South African Astronomical Observatory. This survey project was initiated in Dember 2000, and since then, we kept monitoring a total area of 3 square degrees along the LMC bar and also an area of 1 square degree around the center of the SMC, sufficiently large to do statistical analysis and to make complete catalog of variable red giants in the Magellanic Clouds. The detection limits (S/N=10) of the survey are 17.0, 16.5 and 15.5 at J, H and Ks, respectively. In this article, we present some results on infrared variables that are not detected by the previous optical surveys. We show that they do not fall on the standard period-Ks magnitude relation for Mira-type variables pulsating in the fundamental mode.