Astronomy and Astrophysics – Astrophysics – High Energy Astrophysical Phenomena
Scientific paper
2011-05-03
Astronomy and Astrophysics
Astrophysics
High Energy Astrophysical Phenomena
10 pages, 5 figures, A&A accepted
Scientific paper
For the He/N nova M31N 2007-12b, we analyzed XMM-Newton EPIC and Chandra HRC-I observations of our monitoring program performed at intervals of ten days and added results of a XMM-Newton target of opportunity observation and Swift XRT observations. The supersoft source (SSS) emission started between 21 and 30 d after the optical outburst and ended between 60 and 120 d after outburst, making M31N 2007-12b one of the few novae with the shortest SSS phase known. The X-ray spectrum was supersoft and can be fitted with a white dwarf (WD) atmosphere model with solar abundances absorbed by the Galactic foreground. The temperature of the WD atmosphere seems to increase at the beginning of the SSS phase from ~70 to ~80 eV. The luminosity of M31N 2007-12b during maximum was at the Eddington limit of a massive WD and dropped by ~30% in the observation 60 d after outburst. The radius of the emission region is ~6x10^8 cm. In the four bright state observations, we detected a stable 1110 s pulsation, which we interpret as the WD rotation period. In addition, we detect dips in three observations that might represent a 4.9 h or 9.8 h binary period of the system. Nova envelope models with <50% mixing between solar-like accreted material and the degenerate core of the WD can be used to describe the data. We derive a WD mass of 1.2 Msun, as well as an ejected and burned mass of 2.0x10^{-6} Msun} and 0.2x10^{-6} Msun, respectively. The observed periodicities indicate that nova M31N 2007-12b erupted in an intermediate polar (IP) system. The WD photospheric radius seems to be larger than expected for a non-magnetic WD but in the range for magnetic WDs in an IP system. (abridged)
Della Valle Massimo
Haberl Franck
Hartmann Dieter H.
Henze Matthias
Hernanz Margarida
No associations
LandOfFree
Nova M31N 2007-12b: Supersoft X-rays reveal an intermediate polar? does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Nova M31N 2007-12b: Supersoft X-rays reveal an intermediate polar?, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Nova M31N 2007-12b: Supersoft X-rays reveal an intermediate polar? will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-694002