THE LEO IV DWARF SPHEROIDAL GALAXY: COLOR-MAGNITUDE DIAGRAM AND PULSATING STARS

Journal Article · Fri Jul 10 04:00:00 EDT 2009 · Astrophysical Journal (Online)

DOI:https://doi.org/10.1088/0004-637X/699/2/L125; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21313038

Moretti, Maria Ida ^[1]; Dall'Ora, Massimo; Ripepi, Vincenzo ^[2]

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1. Dipartimento di Astronomia, Universita di Bologna, Bologna (Italy)
2. INAF, Osservatorio Astronomico di Capodimonte, Napoli (Italy)

We 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 {sub RR}) = 21.48 {+-} 0.03 mag (standard deviation of the mean). This leads to a distance modulus of {mu}{sub 0} = 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.

• OSTI ID: 21313038
• Journal Information: Astrophysical Journal (Online), Journal Name: Astrophysical Journal (Online) Journal Issue: 2 Vol. 699; ISSN 1538-4357
• Country of Publication: United States
• Language: English

Related Subjects

99 GENERAL AND MISCELLANEOUS
COLOR
MILKY WAY
PHOTOMETRY
PULSATIONS
SATELLITES
VARIABLE STARS