Two Luminous Post-AGB Stars in the Galactic Globular Cluster M19

We report the discovery of a luminous "yellow" post-asymptotic-giant-branch (PAGB) star in globular cluster (GC) M19 (NGC 6273), identified during our uBVI survey Galactic GCs. The photometric system is optimized to detect stars with large Balmer discontinuities, indicating very low surface gravities and high luminosities. spectral-energy distribution (SED) consistent an effective temperature about 6250 K gravity $\log g=0.5$. use Gaia data show that star's proper motion radial velocity are membership. One aim program test yellow PAGB as candidate Population II standard candles for determining extragalactic distances. derive visual absolute magnitude $M_V=-3.39\pm0.09$ star. This close agreement $M_V$ values found GCs omega Cen, NGC 5986, M79, narrow luminosity function. These objects four magnitudes brighter than RR Lyrae variables, they can largely avoid issues interstellar extinction problem I distance indicators. also second object M19, this one hotter "UV-bright" Its SED 11,750 g=2.0$. two have nearly identical bolometric luminosities, L/L_\odot=3.24$ 3.22, respectively.