Characterizing The Variability of Long Period Variable Stars in the r ≤ 2 kpc Solar Neighborhood With Gaia and ZTF

Periods of variability are a key characteristic of long-period variable (LPV) stars. Periods are potentially related to an LPV’s initial mass, mass loss rate, metallicity, circumstellar envelope thickness, and luminosity. We develop a fitting algorithm combining Jimenez-Esteban et al. (2021) style least-squares regression fits and the Lomb-Scargle Periodogram to fit periods to 36,000 ZTF-Gaia crossmatched LPVs in the solar neighborhood (r ≤ 2). We take advantage of the normalization of Gaia DR2 and ZTF DR3 light curves and long-time baselines to reduce the errors on our fit periods. We successfully fit periods to 93% of our sources and identify a sample of sources with periods consistent with frequencies of variability published by Gaia. We use a sample of BAaDE-Gaia-ZTF crossmatched LPVs with consistent periods to reproduce a log period–k-band apparent magnitude period-luminosity relationship (PLR) in the solar neighborhood. We find that the PLR for LPVs in the solar neighborhood is flat, and hypothesize that the solar neighborhood PLR is dependent on an LPV’s metallicity and circumstellar shell thickness.