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We investigate the mechanism to reproduce notable spectral features at the ignition phase of nova explosion observed for a super-Eddington X-ray transient source MAXI J0158$-$744 in the Small Magellanic Cloud. These are a strong Ne IX emission line at 0.92 keV with a large equivalent width of $0.32^{+0.21}_{-0.11}$ keV and the absence of Ne X line at 1.02 keV. In this paper, we calculate the radiative transfer using a Monte Carlo code, taking into account the line blanketing effect due to transitions of N, O, Ne, Mg and Al ions in an accelerating wind emanating from a white dwarf with a structure based on a spherically symmetric stationary model. We found that the strong Ne IX line can be reproduced if the mass fraction of Ne is enhanced to $10^{-3}$ or more and that of O is reduced to $sim5times10^{-9}$ or less and that the absence of other lines including Ne X ions at higher energies can be also reproduced by the line blanketing effect. This enhancement of the Ne mass fraction indicates that the ejecta are enriched by Ne dredged up from the surface of the white dwarf composed of O, Ne, and Mg rather than C and O, as already pointed out in the previous work. We argue that the CNO cycle driving this nova explosion converted most of C and O into N and thus reduced the O mass fraction.
We present the observation of an extraordinary luminous soft X-ray transient, MAXI J0158-744, by the Monitor of All-sky X-ray Image (MAXI) on 2011 November 11. This transient is characterized by a soft X-ray spectrum, a short duration (1.3 x 10^3 s <
Wide-Field MAXI (WF-MAXI: Wide-Field Monitor of All-sky X-ray Image) is a proposed mission to detect and localize X-ray transients including electro-magnetic counterparts of gravitational-wave events such as gamma-ray bursts and supernovae etc., whic
Phase-resolved spectroscopy of the newly discovered X-ray transient MAXI J0556-332 has revealed the presence of narrow emission lines in the Bowen region that most likely arise on the surface of the mass donor star in this low mass X-ray binary. A pe
It is now widely accepted that most ultraluminous X-ray sources (ULXs) are binary systems whose large (above $10^{39}$ erg s$^{-1}$) apparent luminosities are explained by super-Eddington accretion onto a stellar-mass compact object. Many of the ULXs
We probe the properties of the transient X-ray pulsar MAXI J1409$-$619 through textit{RXTE} and textit{Swift} follow up observations of the outburst in 2010. We are able to phase connect the pulse arrival times for the 25 days episode during the outb