GRB 021004: a Massive Progenitor Star Surrounded by Shells
نویسنده
چکیده
We present spectra of the optical transient of GRB 021004 obtained with the HobbyEberly Telescope starting 15.48, 20.31 hours, and 4.84 days after the γ-ray burst and a spectrum obtained with the H. J. Smith 2.7 m Telescope starting 14.31 hours after the γ-ray burst. GRB 021004 is the first burst afterglow for which the spectrum is dominated by absorption lines from high ionization species with multiple velocity components separated by up to 3000 km s−1. We argue that these absorption lines are
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