Two new ejecta-dominated Galactic supernova remnants: G337.2-0.7 and G309.2-0.6

We present the analysis of new X-ray observations of two Galactic radio sup ernova remnants (SNRs), G337.2-0.7 and G309.2-0.6. Both remnants exhibit li ne-rich thermal spectra that require highly nonsolar elemental abundance ra tios. In each case, Si and S are unequivocally overabundant compared to sol ar, based purely on the measured equivalent width of the K alpha line compl ex. Detailed nonequilibrium ionization spectral analysis of these remnants, using a single-temperature, single ionization age model, confirms the over abundances, yielding Si, S, and Ar abundances many times their solar values : 3-5 times solar for G337.2-0.7 and greater than 3-10 times solar for G30 9.2-0.6. We also find that for both remnants, Ne and Mg are underabundant r elative to Si, and for G309.2-0.6, Ca and Fe are relatively underabundant a s well. This is the first detection of metal-rich, nonsolar abundance mater ial in these remnants, identifying them as young ejecta-dominated SNRs. Fur ther support for their youth comes from the distances that we estimate from the fitted column densities (less than 15 kpc for G337.2-0.7, and 4 +/- 2 kpc for G309.2-0.6). From the implied sizes of the remnants at these distan ces we infer relatively young ages (2000-4500 years for G337.2-0.7 and 700- 4000 years for G309.2-0.6). Finally, we note that no compact object has yet been found within G337.2-0.7, but an X-ray point source is evident within the radio shell of G309.2-0.6, although its nature remains unknown.