The Isaac Newton Telescope Monitoring Survey of Local Group Dwarf Galaxies-VIII. A Census of Long-Period Variable Stars across the Andromeda Dwarf Satellite System

TL;DR

This work presents a comprehensive time-series photometric survey of Andromeda’s dwarf satellites using the INT/WFC to identify ~2800 LPV candidates across 17 systems. It delivers two public catalogs—the full stellar populations and the LPV subset—facilitating studies of quenching, mass distributions, and dust production in low-mass galaxies. The analysis combines robust LPV detection via Welch–Stetson indices, TRGB-based distance determinations with Sobel edge detection, and structural measurements (half-light radii), supplemented by cross-matches to infrared surveys (DUSTiNGS). The results reveal LPV-rich, intermediate-age populations across the satellites, with TRGB distances spanning a broad range and inner satellites showing more dusty, high-amplitude LPVs, suggesting modest environmental effects. Overall, the data provide key benchmarks for stellar evolution and galaxy assembly in the Local Group and enable future work on star-formation histories and dust production in dwarf systems.

Abstract

We present a comprehensive catalog, in the Sloan $i$ and Harris $V$ filters, of long-period variable (LPV) stars in the spheroidal dwarf satellites of the Andromeda galaxy, based on a dedicated survey for variable stars in Local Group dwarf systems. Using photometric time-series data obtained with the Wide Field Camera (WFC) on the 2.5 m Isaac Newton Telescope (INT), we identify approximately 2800 LPV candidates across 17 Andromeda satellites, spanning a broad range in luminosity and variability amplitude. This study is accompanied by a public data release that includes two comprehensive catalogs, a catalog of the complete stellar populations for each galaxy and a separate catalog listing all identified LPV candidates. Both are available through CDS/VizieR and provide a valuable resource for investigating quenching timescales, stellar mass distributions, and the effects of mass-loss and dust production in dwarf galaxies. We derive updated structural parameters, including newly measured half-light radii, and determine distance moduli using the Tip of the Red Giant Branch (TRGB) method with Sobel-filter edge detection, yielding values between $23.38\pm0.06$ and $25.35\pm0.06$ mag.

Figures (18)

• Figure 1: Satellite galaxies of Andromeda. The semi-major axis of the galaxies is represented proportionally to their actual sizes, based on data from Table \ref{['table:objects']}.
• Figure 1: Light-curve example of long-period variable candidates. The black solid line represents the best fit for the observational data.
• Figure 2: The red curves show Gaussian functions fitted to the histograms of the variability index $L$ for the And V stellar population. The negative part of the blue histogram ($L<0$) is mirrored about this value. Vertical black dashed-lines indicate the variability index thresholds adopted in each magnitude bin.
• Figure 2: Light-curve example of long-period variable candidates. The black solid line represents the best fit for the observational data.
• Figure 3: The observed regions of the And III Galaxy, with black dots representing data from the Isaac Newton Telescope and red dots indicating observations from the Spitzer Space Telescope.