[Previous] | [Session 85] | [Next]
J. DePasquale, E.M. Sion (Villanova Un.)
We consider the presence of absorption lines due to accreted metals in the photosphere of the magnetic (28 MG) white dwarf in the prototype polar AM Herculis. We have applied the Massa-Fitzpatrick (2000) flux calibration correction to the archival IUE NEWSIPS SWP spectra of AM Herculis, obtained during the optical low states when the accretion rate is very low and emission due to thermal bremstrahlung and cyclotron processes is essentially absent. We have coadded low state spectra at the same UV maximum phase ~0.6 (main accreting pole most directly exposed to the observor) and UV minimum phase ~0.1 (line of sight perpendicular to the magnetic field). We have used the model atmosphere codes TLUSTY195 and SYNSPEC42 to determine the surface temperature of the white dwarf at each UV phase during quiescence and the chemical abundance of detected metal species. We discuss our abundance results in the context of magnetic accretion physics in AM Herculis systems.
This research was supported in part by NSF grant AST 99-01955, NASA ADP grant NAG5-8388 and by summer research funding from the NASA- Delaware Space Grant Colleges Consortium.