Chandra HETG Spectra of SN 1987A at 20 years

摘要

We have undertaken deep, high-resolution observations of SN 1987A at ~20years after its explosion with the Chandra HETG and LETG spectrometers. Here wepresent the HETG X-ray spectra of SN 1987A having unprecedented spectralresolution and signal-to-noise in the 6 A to 20 A bandpass, which includes theH-like and He-like lines of Si, Mg, Ne, as well as O VIII lines and bright FeXVII lines. In joint analysis with LETG data, we find that there has been asignificant decrease from 2004 to 2007 in the average temperature of thehighest temperature component of the shocked-plasma emission. Model fitting ofthe profiles of individual HETG lines yields bulk kinematic velocities of thehigher-Z ions, Mg and Si, that are significantly lower than those inferred fromthe LETG 2004 observations.