Rapid temporal variations of interstellar absorption lines in the Carina Nebula

Two observations of the complex interstellar absorption-line profiles in th e UV spectrum of CPD -59 degrees 2603, obtained 22 months apart in the R si milar to 110,000 mode of the Space Telescope Imaging Spectrograph on the Hu bble Space Telescope, reveal substantial variations in the intensities of s everal high-velocity components, including the virtual disappearance of one of them. These are the first observations of interstellar temporal variati ons in dominant ions to our knowledge. The most probable interpretation is motion across the line of sight of discrete absorbing features in the near foreground of the O-type star, within the Carina Nebula. Ground-based surve y data also indicate that the extreme interstellar profiles throughout this region originate relatively near the most massive stars, suggesting an ori gin related to their stellar winds. The morphological similarity of these p rofiles to a low-ionization, narrow-line system in a quasi-stellar object ( QSO) spectrum is pointed out. Time variability may provide a critical test among different interpretations of such QSO systems.