Study of variable stars in the MOA data base: long-period red variables in the Large Magellanic Cloud - II. Multiplicity of the period-luminosity relation

Abstract

Data for 4.4 million stars from the Microlensing Observations in Astrophysics (MOA) project are compared with the near-infrared data of the Deep Near Infrared Southern Sky Survey (DENIS). More than 4000 stars observed in both projects show a quite periodic light curve. Among them, a number of stars are likely eclipsing variables, and the others seem to be pulsating stars. The Ks magnitudes of these red variables are in the range 10-12.5 but a minor clump at K S 12.2 mag is also found. The multiplicity of the period-luminosity relation is confirmed, but most of the regular, large-amplitude variables are found on the relation established for the Mira stars. We study the properties of the variables on the colour-magnitude diagram constructed with the MOA red band R m and Ks of DENIS. Multiplicity of the period-luminosity relation is briefly discussed in relation to the excitation mechanism of red pulsating variables.