A homogenised distance catalogue for the Galactic Post-AGB population

Shane Vickers, D.J. Frew, Q.A. Parker, I. Bojicic & M.S. Owers

Macquarie University, Australia

Post-AGB (PAGB) stars are the short-lived, low-intermediate mass objects transitioning from the asymptotic giant branch (AGB) to the white dwarf (WD) phase. These objects are characterised by a constant, core-mass dependent luminosity and a large infrared excess caused by the dusty envelope ejected at the top of the AGB. PAGB stars provide us with insights into the evolution of their direct descendants, planetary nebulae (PNe). The calculation of physical characteristics of PAGB are dependent on accurately determined distances, which are scarcely available in the literature. Using the existing Torun catalogue for PAGB objects and supplementing this with archival data, we have determined distances to the entire Galactic population of PAGB stars by modelling their spectral energy distributions (SED) with black bodies and numerically integrating over the entire wavelength range to determine the total integrated flux of the object. For the bulk of the PAGB stars we have assumed the luminosities of these objects based on their positional characteristics and stellar evolution models. The RV Tauri stars however are known to follow a period-luminosity relation (PLR) reminiscent of type-2 Cepheids, so for these variable PAGB stars we have determined their luminosities via the PLR. Here we present the first homogeneously determined catalogue of distances for the entire Galactic population of PAGB stars. This will allow us to overcome the biggest obstacle to uncovering the mystery of these poorly understood objects which play a vital part in the chemical enrichment of the Galaxy.

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