Long-term photometry and periods for 261 nearby pulsating M giants

TL;DR

This study provides detailed long-term photometric data and period analysis for 261 nearby pulsating M giants, revealing their variability characteristics and comparing period ratios with those in the Large Magellanic Cloud.

Contribution

It offers the first comprehensive period determination for most of these M giants and compares their pulsation properties with extragalactic counterparts.

Findings

87% of the stars are multi-periodic variables

Period ratios match those in the Large Magellanic Cloud

Reliable K-band magnitudes are derived for the sample

Abstract

We present the results of a 5.5-year CCD photometric campaign that monitored 261 bright, southern, semi-regular variables with relatively precise Hipparcos parallaxes. The data are supplemented with independent photoelectric observations of 34 of the brightest stars, including 11 that were not part of the CCD survey, and a previously unpublished long time-series of VZ Cam. Pulsation periods and amplitudes are established for 247 of these stars, the majority of which have not been determined before. All M giants with sufficient observations for period determination are found to be variable, with 87% of the sample (at S/N >= 7.5) exhibiting multi-periodic behaviour. The period ratios of local SRVs are in excellent agreement with those in the Large Magellanic Cloud. Apparent K-band magnitudes are extracted from multiple NIR catalogues and analysed to determine the most reliable values. We review the effects of interstellar and circumstellar extinction and calculate absolute K-band magnitudes using revised Hipparcos parallaxes.