Variable Stars in Metal-Rich Globular Clusters. IV. Long Period Variables in NGC 6496

TL;DR

This study identifies and characterizes long period variables and eclipsing binaries in the metal-rich globular cluster NGC 6496 through two-year VI-band photometry, comparing findings with other stellar populations and models.

Contribution

It reports the discovery of 13 new variable stars in NGC 6496, clarifies their types and membership, and analyzes their properties in relation to other clusters and theoretical models.

Findings

Six LPVs are likely cluster members.

Period-luminosity relation aligns with LMC and 47 Tuc LPVs.

Reddening E(B-V) ~ 0.21 mag and distance modulus ~ 15.60 mag.

Abstract

We present VI-band photometry for stars in the metal-rich globular cluster NGC 6496. Our time-series data were cadenced to search for long period variables (LPVs) over a span of nearly two years, and our variability search yielded the discovery of thirteen new variable stars, of which six are LPVs, two are suspected LPVs, and five are short period eclipsing binaries. An additional star was found in the ASAS database, and we clarify its type and period. We argue that all of the eclipsing binaries are field stars, while 5-6 of the LPVs are members of NGC 6496. We compare the period-luminosity distribution of these LPVs with those of LPVs in the Large Magellanic Cloud and 47 Tucanae, and with theoretical pulsation models. We also present a VI color magnitude diagram, display the evolutionary states of the variables, and match isochrones to determine a reddening of E(B-V) ~ 0.21 mag and apparent distance modulus of ~ 15.60 mag.