The globular cluster M10 reassessment of stellar membership, distance, and age using its variable and HB stars. (2020)
Keywords :
stars evolution - stars: fundamental parameters - stars: horizontal branch - stars: variables: RR Lyrae - globular clusters: individual: (M10)
Abstract:Time-series VI CCD photometry of the globular cluster M10 (NGC 6254) is employed to perform a detailed identification, inspection of their light curves, their classification and their cluster membership, of all the known variables reported up to 2018. The membership analysis is based on the Gaia-DR2 positions and proper motions. The metallicity of the cluster is estimated based on the sole RRc star known in the cluster. The Fourier decomposition of its light curve leads to [Fe/H]_ZW_=-1.59+/-0.23dex. The mean cluster distance, estimated by several independent methods is 5.0+/-0.3kpc. A multi-approach search in a region of about 10x10arcmin^2^ around the cluster revealed three new variables, one SX Phe (V35) and two sinusoidal
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The data used in this work were obtained from three sites. The first
set of data was obtained with the 0.84m telescope at the San Pedro
Mertir Observatory, (Baja California, Mexico), during 16
non-consecutive nights, between 2018 June 18th and 2019 July 01th. We
used a Spectral Instrument CCD of 1024x1024 pixels with a scale of
0.444arcsec/pix, translating to an FoV of approximately
7.57x7.57arcmin^2^. The second set of data was obtained at the Bosque
Alegre Astrophysical Station of the Cordoba Observatory, Universidad
Nacional de Cordoba, Argentina, with the 1.54-m telescope.
Observations were acquired during 5 non-consecutive nights between
2018 August 11th and 2019 September 02th. The detector in 2018 was a
CCD KAF-16803 of 4096x4096-pixels, and in 2019 a CCD KAF-6303E of
3072x2048-pixels. The FoV on the first CCD was 16.9x16.9-arcmin^2^,
and on the second one 12.6x8.4-arcmin^2^. In both seasons, the
detectors were binned 2x2 for a scale of 0.496arcsec/pix, and the
frames were trimmed to a maximum size of approximately 10arcmin^2^ in
order to avoid images severely affected by coma. The third set of data
was obtained using the 2m telescope at the Indian Astronomical
Observatory (IAO) in Hanle, India on 1 night on 2020 April 24th. The
detector used was a SITe ST-002 thinned backside illuminated CCD of
2048x2048-pixels with a scale of 0.296arcsec/pix, which translates
into a FoV of approximately 10.1x10.1-arcmin^2^.
V and I time-series CCD photometry for known variables in the
10.1'x10.1' filed of view of NGC 6254 (M10).
Armando Arellano Ferro, armando(at)astro.unam.mx
