  During the APPLES parallel campaign, the HST Advanced Camera for Surveys has
resolved a distant stellar system, which appears to be an isolated dwarf
galaxy. It is characterized by a circularly symmetric distribution of stars
with an integrated magnitude m(F775W) = 20.13 +- 0.02, a central surface
brightness of ~ 21.33 +- 0.18 mag/arcsec^2 and a half-light radius of ~ 1.8
arcsec. The ACS and VLT spectra show no evidence of ionized gas and appear
dominated by a 3 Gyr old stellar population. The OB spectral type derived for
two resolved stars in the grism data and the systemic radial velocity of ~ 670
km/s measured from the VLT data give a fiducial distance of ~ 9 +- 2 Mpc. These
findings, with the support of the spatial morphology, would classify the system
among the dwarf spheroidal (dSph) galaxies. Following the IAU rules, we have
named this newly discovered galaxy APPLES 1. An intriguing peculiarity of
APPLES 1 is that the properties (age and metallicity) of the stellar content so
far detected are similar to those of dSph galaxies in the Local Group, where
star formation is thought to be driven by galaxy interactions and mergers. Yet,
APPLES 1 seems not to be associated with a major group or cluster of galaxies.
Therefore, APPLES 1 could be the first example of a field dSph galaxy with
self-sustained and regulated star formation and, therefore, would make an
interesting test case for studies of the formation and evolution of unperturbed
dSph galaxies.
