paper

Chandra observations of nova KT Eridani in outburst

arXiv:2108.03577 · doi:10.1093/mnras/stab2298

Abstract

We analyse here four observations of nova KT Eri (Nova Eri 2009) done with the Chandra High Resolution Camera Spectrometer (HRC-S) and the Low Energy Transmission Grating (LETG) in 2010, from day 71 until day 159 after the optical maximum, in the luminous supersoft X-ray phase. The spectrum presents many absorption features with a large range of velocity, from a few hundred km s to 3100 km s in the same observation, and a few prominent emission features, generally redshifted by more than 2000 km s. Although the uncertainty on the distance and the WD luminosity from the approximate fit do not let us rule out a larger absolute luminosity than our best estimate of erg s, it is likely that we observed only up to 40% of the surface of the white dwarf, which may have been partially hidden by clumpy ejecta. Our fit with atmospheric models indicate a massive white dwarf in the 1.15-1.25 M range. A thermal spectrum originating in the ejecta appears to be superimposed on the white dwarf spectrum. It is complex, has more than one component and may be due to a mixture of photoionized and shock ionized outflowing material. We confirm that the 35 s oscillation that was reported earlier, was detected in the last observation, done on day 159 of the outburst.

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