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HST/STIS observations of sdBV stars: testing diffusion and pulsation theory

Heber, U.; Chayer, P.; Fontaine, G. +3 more

We present the initial results of an abundance analysis of echelle UV spectra of five hot subdwarf B (sdB) stars. These stars have been identified as core helium burning objects on the extreme Horizontal Branch. Around 5% of sdBs show short-period acoustic-mode oscillations. Models predict that these oscillations are due to an opacity bump caused …

A new mechanism for the crab fingers

Carlqvist, P.

Images of the outer filamentary parts of the Crab Nebula, earlier obtained with the Hubble Space Telescope WFPC2, are reconsidered. On inspection of the images it is found that most of the mainly radially oriented fingers possess an internal structure, usually in the form of two or more filaments. For some of the fingers there are clear signs that…

Evidence for an Ionized Rotating Structure Around RW Aur

Gómez de Castro, Ana I.; Verdugo, Eva

Profiles of the UV semiforbidden lines of C III and Si III of RW Aur have been obtained with the HST/STIS. The C III profile shows two high velocity components at v = +/- 170 km s^-1 and a central one. The Si III profile is very broad (FWHM = 293 km s^-1) and the high velocity components are unresolved. It is shown that the hig…