Chandra observation of Nova SMC 2016

ATel #9810; M. Orio (University of Wisconsin and INAF-Padova, Italy), Ehud Behar (Department of Physics, Technion, Haifa, Israel), Thomas Rauch (Institute for Astronomy and Astrophysics, Eberhard Karls University, Tuebingen, Germany) and Polina Zemko (Dept of Physics and Astronomy, Padova University, Italy) on behalf of a larger collaboration
on 30 Nov 2016; 09:59 UT
Distributed as an Instant Email Notice Novae
Credential Certification: Marina Orio (orio@astro.wisc.edu)

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Nova SMC 2016 (MASTER OT J010603.18-744715.8; see ATel #9621, #9733) was observed with Chandra, the High Resolution Camera (HRC-S) and the Low Energy Transmission Grating (LETG) on 2017 November 17-18 with an exposure time of approximately 8 hours and 20 minutes. A luminous supersoft X-ray source was detected with a count rate of about 8.6 and 9 counts/s in the -1 and +1 order, respectively. The spectrum shows a stellar continuum, revealing a very hot white dwarf with an effective temperature of about 650,000 K, and deep absorption features, mainly of carbon and nitrogen. We also tentatively identified several absorption features due to transitions of sulfur (S VIII, S X and S XI) that may be attributed to an Oxygen-Neon white dwarf, although more work is necessary for a correct atmospheric model. All absorption features are blue shifted by about 1700 km/s. Some emission lines appear to be superimposed on the spectrum, mostly of nitrogen (N VI), which are likely originating in the ejecta. The zero order light curve measured with the HRC-S detector shows large variability on different time scales. A more complete analysis is under way.