Status Report

Circumstellar features in hot DA white dwarfs

By SpaceRef Editor
January 13, 2003
Filed under , ,

Astrophysics, abstract

From: Nigel Bannister <[email protected]>
Date: Mon, 13 Jan 2003 14:11:12 GMT (440kb)

Circumstellar features in hot DA white dwarfs


Comments: 20 figures, 21 pages

We present a phenomenological study of highly ionised, non-photospheric
absorption features in high spectral resolution vacuum ultraviolet spectra of
23 hot DA white dwarfs. Prior to this study, four of the survey objects (Feige
24, REJ 0457-281, G191-B2B and REJ 1614-085) were known to possess these
features. We find four new objects with multiple components in one or more of
the principal resonance lines: REJ 1738+665, Ton 021, REJ 0558-373 and WD
2218+706. A fifth object, REJ 2156-546 also shows some evidence of multiple
components, though further observations are required to confirm the detection.
We discuss possible origins for these features including ionisation of the
local interstellar environment, the presence of material inside the
gravitational well of the white dwarf, mass loss in a stellar wind, and the
existence of material in an ancient planetary nebula around the star. We
propose ionisation of the local interstellar medium as the origin of these
features in G191-B2B and REJ 1738+665, and demonstrate the need for higher
resolution spectroscopy of the sample, to detect multiple ISM velocity
components and to identify circumstellar features which may lie close to the
photospheric velocity.

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