|Title:||Spectral analysis of very hot H-deficient [WCE]-type central stars of planetary nebulae|
|Date:||Thursday, 4 December 2014|
|Time:||11:00 - 12:00|
Central stars of planetary nebulae, or CSPNe, are evolved stages of low- and intermediate-mass stars. They are very hot, with surface temperatures between 20 000 and 200 000 K, and many of them present signatures of strong stellar winds in their spectra. We analysed ultraviolet FUSE, IUE, and HST/STIS spectra of five of the hottest [WCE]-type central stars of planetary nebulae: NGC 2867, NGC 5189, NGC 6905, Pb 6, and Sand 3. The analysis leveraged on our grid of synthetic spectra, calculated with the non-LTE stellar atmosphere code CMFGEN, which accounts for stationary spherically symmetric mass-loss, line blanketing and wind clumping. The grid includes many ionic species that ha ve been neglected in previous works, is a useful tool to plan observations, and most importantly, enables systematic and uniform analyses of observed spectra. Solid determinations of photospheric and wind parameters are essential to tackle questions concerning low and intermediate mass stellar evolution and possible evolutionary links among different CSPN sub-types, the wind driving mechanism and the properties of the surrounding nebulae. The grids are being made available on-line at http://dolomiti.pha.jhu.edu/planetarynebulae.html.
Keller et al. 2014, MNRAS, 442, 1379. UV spectral analysis of very hot H-deficient [WCE]-type central stars of planetary nebulae: NGC 2867, NGC 5189, NGC 6905, Pb 6 and Sand 3.
Keller et al. 2011, MNRAS, 418, 705. A new grid of synthetic spectra for the analysis of [WC]-type central stars of planetary nebulae.