V471 Tau was observed under the FUSE program M112 (Periodic Channel Coalignment) together with other bright UV sources to check the alignment of the FUSE channels. During the observation the FUSE telescope was performing X and Y scans in the field of view of the target and therefore the FUV flux of V471 Tau was collected only a fraction of the time. The present FUSE spectrum was obtained by integrating only during the time V471 Tau was on target with a constant FUV flux. In the first and second exposures we selected 250s each of good exposure time, in the 3rd - 300s, in the 4th - 800s, and in the 5th and last exposure 500s, totaling 2145s of good exposure time. The FUSE spectrum of V471 Tau is mainly that of a WD atmosphere with Hydrogen, rotating slowly. There is little absorption except for the orders of the Lyman series. The Si and C lines were fit using very low abundances and with a rotational velocity of 250 km/s, which is about four times larger than expected. The broadening of the lines could possibly be due to an unresolved Zeeman splitting as suggested by Sion et al. (2012) who carried out an analysis of the HST/STIS spectra of V471 Tau.

          Bibliography

FUSE Data

Synthetic Spectrum

Click to see larger version of the plot

These data and models were published in the paper:

Godon, P., Sion, E.M., Levay, K., Linnell, A.P., Szkody, P., Barrett, P.E., Hubeny, I., Blair, W.P. 2012, ApJS, in press

Notes on figures:

When a model is shown, the portions of the observed spectrum that have been masked before the spectral fit are in blue, while the rest of the observed spectrum is in red. The model fit is shown the solide line in black (or possibly white). If the model is a composite made of a disk model and a white dwarf model, then these are shown with the dashed- and dotted lines (respectively). Some models include the effect of quasi-molecular HI absorption features, these are labelled "Q-mol" in the spectrum.