Asymptotic Giant Branch Stars in the Leo I Dwarf Spheroidal Galaxy
  Twenty six Asymptotic Giant Branch (AGB) variables are identified in the
Local Group galaxy Leo I. These include 7 Mira and 5 semi-regular variables for
which periods, amplitudes and mean magnitudes are determined. The large range
of periods for the Miras, 158<P<523 days, suggests an AGB spanning a
significant age range. The youngest must be around 1.6 Gyr while the oldest
could be 10 Gyr or more. Two of these old Miras are found in the outer regions
of Leo I (over 490 arcsec from the centre) where stars on the extended AGB are
rare. They could provide an interesting test of third dredge-up and mass loss
in old stars with low metallicity and are worth further detailed investigation.
At least two stars, one a Mira, the other an irregular variable, are undergoing
obscuration events due to dust ejection.
  An application of the Mira period-luminosity relation to these stars yields a
distance modulus for Leo I of (m-M)=21.80 \pm 0.11 mag (internal), \pm 0.12
(total) (on a scale that puts the LMC at 18.39 mag) in good agreement with
other determinations.
