Metallicity Determinations of RR Lyrae on the APOGEE2 Scale Using TESS Lightcurves

Using large, modern surveys of data, we revisit the metallicity calibration of RR Lyrae variables from properties of their lightcurves. Analysis of APOGEE2 visit-level spectra has been calibrated to ASPCAP values to obtain reliable [Fe/H] values for RR Lyrae stars. A systematic and robust Fourier analysis of TESS lightcurves from both short- and long-cadence data has also been performed. High-resolution spectra from a large survey combined with high precision and cadence photometry from a space-based telescope gives us an excellent dataset for determining metallicities of RR Lyrae from lightcurve properties. This calibration, coupled with the all-sky coverage of TESS, means we will be able to trace metallicities in the APOGEE2 scale from every Galactic population using these variables