V471 Tauri

The Wayback Machine - https://web.archive.org/web/20110524174627/http://universe.gsfc.nasa.gov/seminars/presentations/walter/v471_7.html

In V471 Tau:

The atmosphere is extended, to at least 2 K star radii.

The gas must be magnetically confined.

The temperature increases with height.

The gas is in co-rotation about the K star.

The gas exhibits blue shifts (flows?) to about 70 km/s.

There are strong and phase-variable asymetries in the absorbing gas.

The asymetries are likely not caused by the WD.

This is consistent with an incomplete shell near the Keplerian co-rotation radius.

Conclusions:

A lot of gas is confined near the the Keplerian co-rotation radius by giant magnetic loops (forming a quasi-dipolar magnetic canopy?).

The H-alpha prominences may be cool condensations within a hotter gas.

The gas in V471 Tau, and the AB Dor pedestal emission, likely have the same origin.

Rapidly rotating stars have large-scale magnetospheres, with transitions regions and coronae to match.