Modeling CHANDRA low energy transmission grating spectrometer observations of classical novae with PHOENIX - I. V4743 Sagittarii

We use the PHOENIX code package to model the X-ray spectrum of Nova V4743 Sagittarii observed with the LETGS onboard the Chandra satellite 19 March 2003. Our atmosphere models are 1D spherical, expanding, line blanketed, and in full non-local thermodynamic equilibrium. To analyze nova atmospheres and related systems with an underlying nuclear burning envelope at X-ray wavelengths, it was necessary to update the code with new microphysics, as discussed in this paper. We demonstrate that the X-ray emission is dominated by thermal bremsstrahlung and that the hard X-rays are dominated by Fe and N absorption. The best fit to the observation is provided at a temperature of Teff = 5.8 × 10 5 K, with Lbol = 50 000 L� .T he models are calculated for solar abundances. It is shown that the models can be used to determine abundances in the nova ejecta.

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