An Infrared Census Of Dust In Nearby Galaxies With Spitzer (DUSTiNGS):
  V. The Period-luminosity Relation For Dusty Metal-Poor AGB Stars
  The survey for DUST In Nearby Galaxies with Spitzer (DUSTiNGS) has identified
hundreds of candidate dust-producing Asymptotic Giant Branch (AGB) stars in
several nearby metal-poor galaxies. We have obtained multi-epoch follow-up
observations for these candidates with the Spitzer Space Telescope and measured
their infrared (IR) lightcurves. This has allowed us to confirm their AGB
nature and investigate pulsation behavior at very low metallicity. We have
obtained high-confidence pulsation periods for 88 sources in seven galaxies. We
have confirmed DUSTiNGS variable star candidates with a 20% success rate, and
determined the pulsation properties of 19 sources already identified as
Thermally-Pulsing AGB (TP-AGB) stars. We find that the AGB pulsation properties
are similar in all galaxies surveyed here, with no discernible difference
between the DUSTiNGS galaxies (down to 1.4% solar metallicity; [Fe/H]=-1.85)
and the far more metal-rich Magellanic Clouds (up to 50% solar metallicity;
[Fe/H]=-0.38). These results strengthen the link between dust production and
pulsation in AGB stars and establish the IR Period-Luminosity (P - L) relation
as a reliable tool (+/- 4%) for determining distances to galaxies, regardless
of metallicity.
