The H I content of the recently discovered field dwarf galaxy APPLES 1

Abstract

We present observations in a search for neutral hydrogen associated with the recently detected field dwarf galaxy APPLES 1, performed with the Parkes radiotelescope. The observed radio spectrum shows no evident (> 3 sigma rms) line emission indicating an upper limit for the HI content of the galaxy of similar to 10(6) M-circle dot and providing an upper value for the M-HI/L-B ratio equal to 2.4 M-circle dot/L-circle dot. The low value of the HI content suggested by the observations, together with the galaxy optical morphology, might indicate that APPLES 1 is a dwarf spheroidal. This indication is in contrast with the evidence of recent star formation, which is typical for dwarf irregular galaxies. This may suggest that APPLES 1 belongs to the class of mixed dwarf irregular/spheroidal transition-type galaxies. We also conclude that the relatively low neutral gas mass in APPLES 1 can be explained by an extended and inefficient star formation process, without the need for a dramatic event such as enhanced star formation or a past encounter with a massive galaxy or galaxy group.