IRSF/SIRIUS JHK_s, Near-Infrared Variable Star Survey in the Magellanic Clouds

摘要

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 December 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 K_S, 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-K_s magnitude relation for Mira-type variables pulsating in the fundamental mode.