Extreme Bal quasars from the Sloan Digital Sky Survey

The Sloan Digital Sky Survey has discovered a population of broad absorption line quasars with various extreme properties. Many show absorption from metastable states of Fe II with varying excitations; several objects are almost completely absorbed bluewards of Mg II; at least one shows stronger absorption from Fe III than Fe II, indicating temperatures T > 35000 K in the absorbing region; and one object even seems to have broad Hβ absorption. Many of these extreme BALs are also heavily reddened, though ''normal'' BALs (particularly LoBALs) from SDSS also show evidence for internal reddening