Pulsating variable stars in the MACHO bulge database: the semiregular variables

摘要

We review the pulsating stars contained in the top 24 fields of the MACHO bulge database, with special emphasis on the red semiregular stars. Based on period, amplitude and color cuts, we have selected a sample of 2000 semiregular variables with 15 < P < 100 days. Their period-luminosity relation is studied, as well ss their spatial distribution. We find that they follow the bar, unlike the RR Lyrae, in these fields.