Type II Cepheids in the Rubin-LSST era

Type II Cepheids are useful distance indicators and stellar tracers for old populations. For instance, they have been used to find the distances of the Magellanic Clouds and to measure their tridimensional geometry. Rubin LSST will allow us to detect and characterize Type II Cepheids in the Local Group galaxies and beyond. It is important to know in advance to which distance and after how many years the survey cadence will permit us to correctly determine the period and the main features of the Type II Cepheids light curves. To this aim, we have built ad hoc templates of all the subclasses of Type II Cepheids (BLHer, WVir, pWVir and RVTau) in the gri bands adopting a large sample of such objects observed by the Zwicky Transient Facility in our galaxy. These templates have been resampled using the last Rubin LSST simulation (baseline\_v3.0\_10yrs) to evaluate the period, amplitude and mean magnitude recovery in various positions in the sky and distances (distant galaxies). These data will allow us to verify up to which distances we can still classify correctly Type II Cepheids compared with classical Cepheids for which the templates in the Rubin LSST bands are already available within our group.