Age Gradients Throughout the Galaxy with O-Miras
  We assemble the largest sample of oxygen rich Miras to date and highlight
their importance for age-dating the components of the Galaxy. Using data from
the Catalina Rapid Transient Survey and the All Sky Automated Survey for
Supernovae, we extract a clean sample of $\sim 2,400$ O-Miras, stretching from
the Galactic Bulge to the distant halo. Given that the period of O-Miras
correlates with age, this offers a new way of determining age gradients
throughout the Galaxy. We use our sample to show (i) disk O-Miras have periods
increasing on moving outwards from ~ 3 to 15 kpc, so the outer disk O-Miras are
younger than the inner disk, (ii) the transition from younger disk to halo
O-Miras occurs at r ~ 15 kpc and is marked by a plummeting in period, (iii)
there exists a population of young O-Miras likely kicked from the disk to
heights of order of |Z| ~ 10 kpc, (iv) great circle counts of old Miras show
strong evidence for distant debris agglomeration associated with the Magellanic
Clouds, (v) seven stars in our samples are located at distances between 200 and
500 kpc surpassing all previously established records, and, finally, (vi)
O-Miras may be present in the Fornax, Sculptor, Sextans and Leo II Galactic
dwarf spheroidals, as well as the distant globular cluster Pal 4. We spotlight
the importance of O-Mira in the Era of Gaia as universal chronometers of the
Galactic populations.
