DWARF SPHEROIDAL SATELLITES OF M31. I. VARIABLE STARS AND STELLAR POPULATIONS IN ANDROMEDA XIX

We present B, V time-series photometry of Andromeda XIX (And XIX), the most extended (half-light radius of 6.'2) of Andromeda's dwarf spheroidal companions, which we observed with the Large Binocular Cameras at the Large Binocular Telescope. We surveyed a 23' x 23' area centered...

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Bibliographic Details
Published in:The Astrophysical journal 2013-12, Vol.779 (1), p.1-17
Main Authors: Cusano, Felice, CLEMENTINI, GISELLA, Garofalo, Alessia, Cignoni, Michele, Federici, Luciana, Marconi, Marcella, Musella, Ilaria, Ripepi, Vincenzo, BOUTSIA, KONSTANTINA, FUMANA, MARCO, GALLOZZI, STEFANO, Testa, Vincenzo
Format: Article
Language:English
Subjects:
AMPLITUDES
Andromeda Galaxy
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
Binoculars
Brackets
CAMERAS
CEPHEIDS
COLOR
DISTANCE
DWARF STARS
INSTABILITY
LUMINOSITY
MAGELLANIC CLOUDS
PHOTOMETRY
SATELLITES
Stars
TELESCOPES
Variable stars
VISIBLE RADIATION
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Summary:We present B, V time-series photometry of Andromeda XIX (And XIX), the most extended (half-light radius of 6.'2) of Andromeda's dwarf spheroidal companions, which we observed with the Large Binocular Cameras at the Large Binocular Telescope. We surveyed a 23' x 23' area centered on And XIX and present the deepest color-magnitude diagram (CMD) ever obtained for this galaxy, reaching, at V ~ 26.3 mag, about one magnitude below the horizontal branch (HB). The CMD shows a prominent and slightly widened red giant branch, along with a predominantly red HB, which extends to the blue to significantly populate the classical instability strip. We have identified 39 pulsating variable stars, of which 31 are of RR Lyrae type and 8 are Anomalous Cepheids (ACs). Twelve of the RR Lyrae variables and three of the ACs are located within And XIX's half light radius. The average period of the fundamental mode RR Lyrae stars ([left angle bracket]P sub(ab)[right angle bracket] = 0.62 days, [sigma] = 0.03 days) and the period-amplitude diagram qualify And XIX as an Oosterhoff-Intermediate system. From the average luminosity of the RR Lyrae stars ([left angle bracket]V(RR)[right angle bracket] = 25.34 mag, [sigma] = 0.10 mag), we determine a distance modulus of (m - M) sub(0) = 24.52 + or - 0.23 mag in a scale where the distance to the Large Magellanic Cloud (LMC) is 18.5 + or - 0.1 mag. The ACs follow a well-defined Period-Wesenheit (PW) relation that appears to be in very good agreement with the PW relationship defined by the ACs in the LMC.
ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/779/1/7