NGC 6426: Colour-Magnitude diagram and variable star population as indicators of metallicity, distance, and age
Abstract
We present new VI CCD photometry of the globular cluster NGC 6426. The membership status of all point sources and, in particular, of all the variables in the field of view is discussed, including four recently detected variables. The double mode nature of variables V3 and V9 is confirmed and their periods are calculated. The presence of a cluster member anomalous Cepheid (V17) is reported. Employing only likely members we produce a decontaminated colour-magnitude diagram (CMD) differentially dereddened, which enables us to compare it with theoretical predictions and to study the variable stars distribution. The mean cluster metallicity and distance were calculated via the RR Lyrae V-band light curve Fourier decomposition and an I-band calibration of the Period-Magnitude-Metallicity relation. Further, a comparison using a Bayesian approach between theoretical isochrones of Dartmouth Stellar Evolution Database (DSED), with a deep HST CMD, gave us independent estimates of distance modulus, metallicity, colour excess, and cluster age.
Related
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BibTeX
@misc{ferro20266426,
title = {{NGC 6426: Colour-Magnitude diagram and variable star population as indicators of metallicity, distance, and age}},
author = {A. Arellano Ferro and R. Michel and D. Deras and M. Vaca Montejano and S. Muneer and I. Bustos Fierro},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.11016},
eprint = {2610.11016},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.11016},
}
RIS
TY - UNPB
TI - NGC 6426: Colour-Magnitude diagram and variable star population as indicators of metallicity, distance, and age
AU - A. Arellano Ferro
AU - R. Michel
AU - D. Deras
AU - M. Vaca Montejano
AU - S. Muneer
AU - I. Bustos Fierro
PY - 2026
DA - 2026/10/07
PB - arXiv
DO - 10.48550/arxiv.2610.11016
UR - https://arxiv.org/abs/2610.11016
AB - We present new VI CCD photometry of the globular cluster NGC 6426. The membership status of all point sources and, in particular, of all the variables in the field of view is discussed, including four recently detected variables. The double mode nature of variables V3 and V9 is confirmed and their periods are calculated. The presence of a cluster member anomalous Cepheid (V17) is reported. Employing only likely members we produce a decontaminated colour-magnitude diagram (CMD) differentially dereddened, which enables us to compare it with theoretical predictions and to study the variable stars distribution. The mean cluster metallicity and distance were calculated via the RR Lyrae V-band light curve Fourier decomposition and an I-band calibration of the Period-Magnitude-Metallicity relation. Further, a comparison using a Bayesian approach between theoretical isochrones of Dartmouth Stellar Evolution Database (DSED), with a deep HST CMD, gave us independent estimates of distance modulus, metallicity, colour excess, and cluster age.
ER -