No abstract available

[en] SN 2006oz is a super-luminous supernova with a mysterious bright precursor that has resisted explanation in standard models. However, such a precursor has been predicted in the dual-shock quark nova model of super-luminous supernovae — the precursor is the supernova event while the main light curve of the super-luminous supernova is powered by the Quark-Nova (explosive transition of the neutron star to a quark star). As the supernova is fading, the Quark-Nova re-energizes the supernova ejecta, producing a 'double-humped' light curve. We show that the quark nova model successfully reproduces the observed light curve of SN 2006oz

No abstract available

[en] The observed contraction of the accretion disks in the dwarf novae U Gem and Z Cha during quiescence is interpreted with simple dynamical models. The standard α-parameter viscosity prescription is replaced by macroscopic constraints that are both computationally convenient and appropriate for the study of an extensive characteristic such as the disk radius. In the first model, quiescent-phase mass accumulation occurs in a torus located at the outer edge of the disk proper. Interaction between the torus and the disk itself is minimal, there being no torque between the two. Contraction occurs as the torus accretes matter of low specific angular momentum from the companion star. The second model corresponds to a torus-disk interaction so large that the torus is no longer a separate entity: mass accumulates throughout the disk in such a way that the surface density has a specified power-law form at all times. These two extreme models thus bracket the range of possible accretion modes

[en] The nova model of hadron-hadron scattering is extended to treat the fragmentation of heavy nuclei, and the results are in agreement with recent experiments. (4 figures, 1 table) (U.S.)

[en] Hot (explosive) hydrogen burning, or the rapid proton capture process (rp-process), occurs in a number of astrophysical environments. Novae and X-ray bursts are the most prominent ones, but accretion disks around black holes and other sites are candidates as well. The expensive and often multidimensional hydrocalculations for such events require an accurate prediction of the thermonuclear energy generation while avoiding full nucleosynthesis network calculations. In the present investigation we present an approximation scheme that leads to accuracy of more than 15% for the energy generation in hot hydrogen burning from 10⁸-1.5x10⁹K, which covers the whole range of all presently known astrophysical sites. It is based on the concept of slowly varying hydrogen and helium abundances and assumes a kind of local steady flow by requiring that all reactions entering and leaving a nucleus add up to a zero flux. This scheme can adapt itself automatically and covers low-temperature regimes, characterized by a steady flow of reactions, as well as high-temperature regimes where a (p,γ)-(γ,p)-equilibrium is established, while β⁺-decays or (α,p)-reactions feed the population of the next isotonic line of nuclei. In addition to a gain of a factor of 15 in computational speed over a full-network calculation and energy generation accurate to more than 15% this scheme also allows the correct prediction of individual isotopic abundances. Thus, it delivers all features of a full network at a highly reduced cost and can easily be implemented in hydrocalculations. copyright 1997 The American Astronomical Society

No abstract available

[en] In this paper, we study the combined sensitivity of T2K-II and NOvA, the world leading long-baseline neutrino oscillation experiments, to CP violation in lepton sector. By operating until the year 2026, T2K-II is expected to collect a total exposure of 20×10²¹ protons-on-target. Meanwhile, NOνA experiment plan to expend the run up to 2024 for accumulating totally an amount of72×10²⁰protons-on-target. By combining T2K-II and NOνA with an ultimate constraint from reactor, the sensitivity to CP-violation is expected to exceed 4σ C.L. It is also pointed out that by reducing the systematic uncertainties of both T2K-II and NOνA to a level of 2 %, the sensitivity to CP-violation will significantly increase with a discovery possibility at 5σ C.L. significance for a particular range of true δCP. (author)

[en] In the Quark–Nova model, Anomalous X-ray Pulsars (AXPs) are quark stars surrounded by a degenerate iron-rich Keplerian ring (a few stellar radii away). AXP bursts are caused by accretion of chunks from the inner edge of the ring following magnetic field penetration. For bright bursts, the inner disk is prone to radiation induced warping which can tilt it into counter-rotation (i.e. retrograde). For AXP 1E2259+586, the 2002 burst satisfies the condition for the formation of a retrograde inner ring. We hypothesize the 2002 burst reversed the inner ring setting the scene for the 2012 outburst and “anti-glitch” when the retrograde inner ring was suddenly accreted leading to the basic observed properties of the 2012 event.

[en] The sources of nuclear uncertainties in nova nucleosynthesis have been identified using hydrodynamical nova models. Experimental efforts have followed and significantly reduced those uncertainties. This is important for the evaluation of nova contribution to galactic chemical evolution, gamma-ray astronomy and possibly presolar grain studies. In particular, estimations of expected gamma-ray fluxes are essential for the planning of observations by means of existing or future satellites