RGS Observations of Peculiar Knots in Tycho.s SNR

Tycho.s SNR provides a pristine laboratory of what remains four and a halfcenturies after a Type Ia SN. We propose an observation of the southeast portionto observe two bright ejecta knots of interest. Both are Ferich, while onecontains significant Si as well. RGS observations of these knots will reveal thenumerous Fe Lshell and Si lines present, from which we can determine the stateof the reverseshocked ejecta, the thermal line broadening present, search foroxygen, an indicator of a doubledegenerate supernova, and possibly measure thetime evolution of the Fe K alpha line at 6.5 keV, something never before done.Observations such as these will be crucial for understanding the physics ofshocked plasmas in preparation for the next generation of high spectral resolution Xray observatories. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]