# Physical properties of galactic RV Tauri stars from Gaia DR2 data

## TL;DR

This study derives the first period-luminosity and period-radius relations for Galactic RV Tauri stars using Gaia DR2 data, revealing a wider pulsational region and mass differences among subtypes.

## Contribution

It provides the first detailed period-luminosity and period-radius relations for Galactic RV Tauri stars based on Gaia DR2 data, confirming their wider pulsational region.

## Key findings

- Wider pulsational region for RV Tauri stars.
- Steeper period-luminosity relation than Type II Cepheids.
- Median masses of RVa and RVb stars are 0.45-0.52 and 0.83 solar masses.

## Abstract

We present the first period-luminosity and period-radius relation of Galactic RV Tauri variable stars. We have surveyed the literature for all variable stars belonging to this class and compiled the full set of their photometric and spectroscopic measurements. We cross-matched the final list of stars with the Gaia DR2 database and took the parallaxes, G-band magnitudes and effective temperatures to calculate the distances, luminosities and radii using a probabilistic approach. As it turned out, the sample was very contaminated and thus we restricted our study to those objects for which the RV Tau-nature was securely confirmed. We found that several stars are located outside the red edge of the classical instability strip, which implies a wider pulsational region for RV Tau stars. The period-luminosity relation of galactic RV Tauri stars is steeper than that of the shorter-period Type II Cepheids, in agreement with previous result obtained for the Magellanic Clouds and globular clusters. The median masses of RVa and RVb stars were calculated to be 0.45-0.52 M$_{\odot}$ and 0.83 M$_{\odot}$, respectively.