Maria Ida Moretti et al 2009 ApJ 699 L125 doi:10.1088/0004-637X/699/2/L125
THE LEO IV DWARF SPHEROIDAL GALAXY: COLOR-MAGNITUDE DIAGRAM AND PULSATING STARS*
FREE ISSUEMaria Ida Moretti1, Massimo Dall'Ora2, Vincenzo Ripepi2, Gisella Clementini3, Luca Di Fabrizio4, Horace A. Smith5, Nathan De Lee6, Charles Kuehn5, Márcio Catelan7,10,11, Marcella Marconi2, Ilaria Musella2, Timothy C. Beers5,8 and Karen Kinemuchi6,9
Show affiliationsWe present the first V, B – V color-magnitude diagram of the Leo IV dwarf spheroidal galaxy, a faint Milky Way satellite recently discovered by the Sloan Digital Sky Survey. We have obtained B, V time-series photometry reaching about half a magnitude below the Leo IV turnoff, which we detect at V = 24.7 mag, and have performed the first study of the variable star population. We have identified three RR Lyrae stars (all fundamental-mode pulsators, RRab) and one SX Phoenicis variable in the galaxy. In the period-amplitude diagram the Leo IV RR Lyrae stars are located close to the loci of Oosterhoff type I systems and the evolved fundamental-mode RR Lyrae stars in the Galactic globular cluster M3. However, their mean pulsation period, 
Pab
= 0.655 days, would suggest an Oosterhoff type II classification for this galaxy. The RR Lyrae stars trace very well the galaxy's horizontal branch, setting its average magnitude at V RR = 21.48 ± 0.03 mag (standard deviation of the mean). This leads to a distance modulus of μ0 = 20.94 ± 0.07 mag, corresponding to a distance of 154 ± 5 kpc, by adopting for the Leo IV dSph a reddening E(B – V) = 0.04 ± 0.01 mag and a metallicity of [Fe/H] = –2.31 ± 0.10.
- Footnote
- Keywords
galaxies: dwarf; galaxies: individual (Leo IV); stars: distances; stars: variables: other; techniques: photometric
- PACS
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98.52.Wz Dwarf galaxies (elliptical, irregular, and spheroidal)
95.80.+p Astronomical catalogs, atlases, sky surveys, databases, retrieval systems, archives, etc.
95.75.De Photography and photometry (including microlensing techniques)
98.35.Ln Stellar content and populations; morphology and overall structure
- Subjects
- Dates
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Issue 2 (2009 July 10)
Received 2009 March 20, accepted for publication 2009 May 29
Published 2009 June 22
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The Leo IV Dwarf Spheroidal Galaxy: Color-Magnitude Diagram and Pulsating Stars
Maria Ida Moretti et al 2009 ApJ 699 L125
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