We present a detailed study of the color magnitude diagram (CMD) of the dwarf spheroidal galaxy Leo I, based on archival Hubble Space Telescope data. Our photometric analysis, confirming previous results on the brighter portion of the CMD, allow us to obtain an accurate sampling of the stellar populations also at the faint magnitudes corresponding to the Main Sequence. By adopting a homogeneous...

Abstract Positioning, Navigation and Timing (PNT) are services generally provided by Global Satellite Systems (GNSS). GNSS reside in medium to high orbital altitudes from the Earth’s surface, resulting weak signal reception. However, user applications increasingly need of higher power strength or alternative PNT solutions. An influx satellites Low Earth Orbit (LEO) driving such innovation techn...

We derive new effective radii and total magnitudes for 5 E and S0 galaxies in the Leo-I group from wide-field CCD images. These are used in conjunction with recent literature velocity data to construct the fundamental plane (FP) of the Leo-I group. The rms scatter that we find is only 6 % in distance. The zero point of this relation provides a calibration of the FP as a distance indicator and d...

We present elemental abundances for multiple HII regions in Leo A and GR 8 obtained from long slit optical spectroscopy of these two nearby low luminosity dwarf irregular galaxies. As expected from their luminosities, and in agreement with previous observations, the derived oxygen abundances are extremely low in both galaxies. High signal-to-noise ratio observations of a planetary nebula in Leo...

We have obtained spectra of three QSO/AGNs with the GHRS aboard the Hubble Space Telescope to search for absorption from low column density gas in the halo of the dwarf spheroidal (dSph) galaxy Leo I. The probe sight lines pass 2.1, 3.7, and 8.1 kpc from the center of the galaxy, but no C IV, Si II, or Si IV absorption is found at the velocity of Leo I. The absence of low-ionization species sug...