MIKE Spectra of GALEX J1931+0117 showing the many absorption lines due to metal that is polluting the white dwarf's atmosphere. The metal lines come from dust that is accreting directly on the surface of the white dwarf at the rate of a small asteroid per year.
MIKE Spectra of Selected WDs
As part of a large monitoring project of DAZs with the MIKE Spectrograph on Magellan, I have observed several nearby WDs to search for metal lines in their photospheres. Below is a selected group of WDs with non-detections of Ca lines, that perhaps can be used for other work. The spectra were reduced with the Kelson Pipeline as detailed in Kelson (2003). The spectra do not have perfect blaze correction, are not corrected for heliocentric velocity offsets, and are not flux calibrated. However, the fidelity of these types of observations is demonstrated with the spectra above of GALEX J193156.8+011745, a heavily polluted DA white dwarf. Each spectrum consists of a gzipped tar file containing blue and red side spectra, covering a total wavelength range of roughly 3500-9500 Angstroms. If you use these spectra, please cite This Conference Proceeding