Improving the distances of post-AGB objects in the Milky Way

[摘要] Post-AGB (PAGB) stars are 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 from the dusty envelope ejected at the top of the AGB. PAGB stars provide insights into the evolution of their direct descendants, planetary nebulae (PNe). Calculation of physical characteristics of PAGB are dependent on accurately determined distances scarcely available in the literature. Using the Torun catalogue for PAGB objects, supplemented with archival data, we have determined distances to the known population of Galactic PAGB stars. This is by modelling their spectral energy distributions (SED) with black bodies and numerically integrating over the entire wavelength range to determine the total integrated object flux. For most PAGB stars we assumed their luminosities are based on their positional characteristics and stellar evolution models. RV Tauri stars however are known to follow a period-luminosity relation (PLR) reminiscent of type-2 Cepheids. For these variable PAGB stars we determined their luminosities via the PLR and hence their distances. This allows us to overcome the biggest obstacle to characterising these poorly understood objects that play a vital part in Galactic chemical enrichment.

[发布机构] Department of Physics and Astronomy, Macquarie University, NSW; 2109, Australia^1;Department of Physics, University of Hong Kong, Pokfulam Road, Hong Kong, Hong Kong^2;Australian Astronomical Observatory, PO Box 915, North Ryde; NSW; 1670, Australia^3

[效力级别] 天文学 [学科分类] 天文学(综合)

[关键词] Archival data;Asymptotic giant branch;Period-luminosity relations;Physical characteristics;Planetary nebulae;Spectral energy distribution;Stellar evolutions;Wavelength ranges