Cepheids and other short-period variables near the Galactic Centre

Abstract

We report the result of our near-infrared survey of short-period variable\nstars (P<60d) in a field-of-view of 20'x30' towards the Galactic Centre.\nForty-five variables are discovered and we classify the variables based on\ntheir light curve shapes and other evidence. In addition to 3 classical\nCepheids reported previously, we find 16 type II Cepheids, 24 eclipsing\nbinaries, one pulsating star with P=0.265d (RR Lyr or delta Sct) and one\nCepheid-like variable whose nature is uncertain. Eclipsing binaries are\nseparated into the foreground objects and those significantly obscured by\ninterstellar extinction. One of the reddened binaries contains an O-type\nsupergiant and its light curve indicates an eccentric orbit. We discuss the\nnature and distribution of type II Cepheids as well as the distance to the\nGalactic Centre based on these Cepheids and other distance indicators. The\nestimates of R0(GC) we obtained based on photometric data agree with previous\nresults obtained with kinematics of objects around the GC. Furthermore, our\nresult gives a support to the reddening law obtained by Nishiyama and\ncollaborators, A(Ks)/E(H-Ks)=1.44, because a different reddening law would\nresult in a rather different distance estimate.\n