Age gradients throughout the Galaxy with LPVs

Using data from the Catalina Surveys and the All Sky Automated Survey for Supernovae, we extract a clean sample of ~2200 O-rich LPVs, stretching from the Galactic Bulge to the distant halo. We estimate ~80 per cent of our selected sample to be comprised of O-rich LPVs.

Given that the period of LPVs correlates with age, this offers a new way of determining age gradients throughout the Galaxy. We use our sample to show (i) disc O-rich LPVs have periods increasing on moving outwards from ~3 to 15kpc, so the outer disc LPVs are younger than the inner disc, (ii) the transition from younger disc to halo LPVs occurs at r ~15kpc and is marked by a plummeting in period, (iii) there exists a population of young O-Miras likely kicked from the disc to heights of order of |Z|~10kpc, and (iv) great circle counts of old LPVs show evidence for distant debris agglomeration associated with the Magellanic Clouds.