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  • Swift detection of the supe...
    Page, K. L; Osborne, J. P; Kuin, N. P. M; Henze, M; Walter, F. M; Beardmore, A. P; Bode, M. F; Darnley, M. J; Delgado, L; Drake, J. J; Hernanz, M; Mukai, K; Nelson, T; Ness, J.-U; Schwarz, G. J; Shore, S. N; Starrfield, S; Woodward, C. E

    Monthly notices of the Royal Astronomical Society, 12/2015, Letnik: 454, Številka: 3
    Journal Article

    V745 Sco is a recurrent nova, with the most recent eruption occurring in February 2014. V745 Sco was first observed by Swift a mere 3.7 h after the announcement of the optical discovery, with the super-soft X-ray emission being detected around 4 d later and lasting for only ∼2 d, making it both the fastest follow-up of a nova by Swift and the earliest switch-on of super-soft emission yet detected. Such an early switch-on time suggests a combination of a very high velocity outflow and low ejected mass and, together with the high effective temperature reached by the super-soft emission, a high mass white dwarf (>1.3 M⊙). The X-ray spectral evolution was followed from an early epoch where shocked emission was evident, through the entirety of the super-soft phase, showing evolving column density, emission lines, absorption edges, and thermal continuum temperature. UV grism data were also obtained throughout the super-soft interval, with the spectra showing mainly emission lines from lower ionization transitions and the Balmer continuum in emission. V745 Sco is compared with both V2491 Cyg (another nova with a very short super-soft phase) and M31N 2008-12a (the most rapidly recurring nova yet discovered). The longer recurrence time compared to M31N 2008-12a could be due to a lower mass accretion rate, although inclination of the system may also play a part. Nova V745 Sco (2014) revealed the fastest evolving super-soft source phase yet discovered, providing a detailed and informative data set for study.