A New Sample of Mid-Infrared Bright, Long-Period Mira Variables from the MACHO Galactic Bulge Fields

TL;DR

This study reports the discovery of 192 new Mira variables in the Galactic Bulge using MACHO mid-infrared data, expanding the known sample and analyzing their properties in various parameter spaces.

Contribution

First identification of a large sample of 192 new Mira variables in the Galactic Bulge from MACHO data, with comprehensive analysis of their light curves and properties.

Findings

Sample mostly consists of luminous, long-period variables.

Total known Mira variables in MACHO Galactic Bulge fields now 1286.

New Mira variables exhibit expected period-colour and period-magnitude relations.

Abstract

Mid-infrared bright objects in the direction of the Galactic Bulge were investigated using time series photometry from the MACHO data archive, which led to the discovery of a large number of long-period variables. Among these, a total of 192 bona-fide Mira variables was identified, which, to the best of our knowledge, are reported here for the first time. Together with the results from our previous investigations, we thereby bring the number of Mira variables found in the MACHO Galactic Bulge fields to a new total of 1286 stars. Light curves, folded light curves and summary data for all new Mira variables are presented and their properties in colour-colour, period-colour and period-magnitude space are investigated. In agreement with our expectations, the present sample of mid-infrared bright objects is composed mostly of luminous, long-period variables.