Invited_talk abstract details
New results from the UV
Abstract
The UV (below about 3000Ang) and far-UV (shortwards of Ly-alpha) domains hold unique clues to unravel the physical parameters of Central Stars of Planetary Nebulae (CSPNe) and the paths for this elusive final stage of stellar evolution, thanks to a wealth of diagnostic transitions from ionic species not observable at other wavelengths.
Intermediate mass stars are the major providers of important elements: understanding how they shed most of their initial mass is critical also for understanding the chemical enrichment of the ISM. Mass-loss diagnostic lines abound in the far-UV and UV, and when the CSPN reaches the hottest Teff before turning on the WD-cooling sequence, and the wind fades, the last wind lines to disappear are in the far-UV. New diagnostic spectral lines for elements such as neon were discovered in the far-UV range. This domain offers also a host of molecular hydrogen diagnostics, tracing the circum-stellar material expelled in previous phases.
UV images and spectra of PNe add critical constraints to their ionization structure and to some abundances.
Finally, the recent UV sky surveys from GALEX, in two UV bands, enabled the first unbiased census of hot-WD and post-AGB objects in the Milky Way, significantly expanding known catalogs and providing statistical constraints to the initial-final mass relation. Linking the end product of intermediate-mass stars evolution to their progenitors contributes to solving the puzzle of the chemical yields.
Intermediate mass stars are the major providers of important elements: understanding how they shed most of their initial mass is critical also for understanding the chemical enrichment of the ISM. Mass-loss diagnostic lines abound in the far-UV and UV, and when the CSPN reaches the hottest Teff before turning on the WD-cooling sequence, and the wind fades, the last wind lines to disappear are in the far-UV. New diagnostic spectral lines for elements such as neon were discovered in the far-UV range. This domain offers also a host of molecular hydrogen diagnostics, tracing the circum-stellar material expelled in previous phases.
UV images and spectra of PNe add critical constraints to their ionization structure and to some abundances.
Finally, the recent UV sky surveys from GALEX, in two UV bands, enabled the first unbiased census of hot-WD and post-AGB objects in the Milky Way, significantly expanding known catalogs and providing statistical constraints to the initial-final mass relation. Linking the end product of intermediate-mass stars evolution to their progenitors contributes to solving the puzzle of the chemical yields.