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The sub-barrier fusion hindrance has been observed in the domain of very low energies of astrophysical relevance. This phenomenon can be analyzed effectively using an uncomplicated straightforward elegant mathematical formula gleaned presuming diffused barrier with a Gaussian distribution. The mathematical formula for cross section of nuclear fusion reaction has been obtained by folding together a Gaussian function representing the fusion barrier height distribution and the expression for classical cross section of fusion assuming a fixed barrier. The variation of fusion cross section as a function of energy, thus obtained, describes well the existing data on sub-barrier heavy-ion fusion for lighter systems of astrophysical interest. Employing this elegant formula, cross sections of interacting nuclei from $^{16}$O + $^{18}$O to $^{12}$C + $^{198}$Pt, all of which were measured down to $<$ 10 $\mu$b have been analyzed. The agreement of the present analysis with the measured values is comparable, if not better, than those calculated from more sophisticated calculations. The three parameters of this formula varies rather smoothly implying its usage in estimating the excitation function or extrapolating cross sections for pairs of interacting nuclei which are yet to be measured. Possible effects of neutron transfers on the hindrance in heavy-ion fusion have been explored., Comment: 7 pages including 7 figures and 2 tables. arXiv admin note: text overlap with arXiv:2107.09451

The hindrance in fusion of heavy-ion reactions crops up in the region of extreme sub-barrier energies. This phenomenon can be effectively analyzed using a simple diffused barrier formula derived assuming a Gaussian distribution of fusion barrier heights. Folding the Gaussian barrier distribution with the classical expression for the fusion cross section for a fixed barrier, the fusion cross section is obtained. The energy dependence of the fusion cross section provides good description to the existing data on sub-barrier heavy-ion fusion for lighter systems of astrophysical interest. Using this simple formula, an analysis has been presented from $^{16}$O + $^{18}$O to $^{12}$C + $^{198}$Pt, all of which were measured down to $<$ 10 $\mu$b. The agreement of the present analysis with the measured values is better than those calculated even from the sophisticated coupled channels calculations. The relatively smooth variation of the three parameters of this formula implies that it may be exploited to estimate the excitation function or to extrapolate cross sections for pairs of interacting nuclei which are yet to be measured. Possible extensions of the present methodology and its limitations have also been discussed., Comment: 6 pages including 7 figures and 1 table. arXiv admin note: substantial text overlap with arXiv:1402.5330

In the present work, we explore the Rossby mode instabilities in neutron stars as sources of gravitational waves. The intensity and time evolution of the emitted gravitational waves in terms of the amplitude of the strain tensor are estimated in the slow rotation approximation using $\beta$-equilibrated neutron star matter obtained from density dependent M3Y effective interaction. For a wide range of neutron star masses, the fiducial gravitational and various viscous time scales, the critical frequencies and the time evolutions of the frequencies are calculated. The dissipative mechanism of the Rossby modes is considered to be driven by the shear viscosity along the boundary layer of the solid crust-liquid core interface as well as in the core and the bulk viscosity. It is found that neutron stars with slower frequency of rotation, for the same mass, radius and surface temperature, are expected to emit gravitational waves of higher intensity., Comment: 9 pages including 8 figures and 1 table. arXiv admin note: text overlap with arXiv:1711.10794; text overlap with arXiv:1302.1204 by other authors

An equation of state (EoS) for symmetric nuclear matter is constructed using the density dependent M3Y effective interaction and extended for isospin asymmetric nuclear matter. Theoretically obtained values of symmetric nuclear matter incompressibility, isobaric incompressibility, symmetry energy and its slope agree well with experimentally extracted values. Folded microscopic potentials using this effective interaction, whose density dependence is determined from nuclear matter calculations, provide excellent descriptions for proton, alpha and cluster radioactivities, elastic and inelastic scattering. The nuclear deformation parameters extracted from inelastic scattering of protons agree well with other available results. The high density behavior of symmetric and asymmetric nuclear matter satisfies the constraints from the observed flow data of heavy-ion collisions. The neutron star properties studied using $\beta$-equilibrated neutron star matter obtained from this effective interaction for pure hadronic model agree with the recent observations of the massive compact stars such as PSR J1614-2230, but if a phase transition to quark matter is considered such agreement is no longer possible., Comment: 17 pages including 12 figures and 6 tables. To be published in Eur. Phys. J. Plus (2014) 129. arXiv admin note: substantial text overlap with arXiv:1309.6793, arXiv:1111.4617, arXiv:0707.4620, arXiv:0905.1599, arXiv:0907.5350, arXiv:nucl-th/0407001; and text overlap with arXiv:0709.0900 by other authors

We present a systematic study of the properties of pure hadronic and hybrid compact stars. The nuclear equation of state (EoS) for beta-equilibrated neutron star matter was obtained using density dependent effective nucleon-nucleon interaction which satisfies the constraints from the observed flow data from heavy-ion collisions. The energy density of quark matter is lower than that of this nuclear EoS at higher densities implying the possibility of transition to quark matter inside the core. We solve the Einstein's equations for rotating stars using pure nuclear matter and quark core. The beta- equilibrated neutron star matter with a thin crust is able to describe highly massive compact stars but find that the nuclear to quark matter deconfinement transition inside neutron stars causes reduction in their masses. Recent observations of the binary millisecond pulsar J1614-2230 by P. B. Demorest et al. [1] suggest that the masses lie within 1.97\pm0.04 M\odot where M\odot is the solar mass. In conformity with recent observations, pure nucleonic EoS determines that the maximum mass of NS rotating with frequency below r-mode instability is ~1.95 M\odot with radius ~10 kilometers. Although compact stars with quark cores rotating with Kepler's frequency have masses up to ~2 M\odot, but if the maximum frequency is limited by the r-mode instability, the maximum mass ~1.7 M\odot turns out to be lower than the observed mass of 1.97\pm0.04 M\odot, by far the highest yet measured with such certainty, implying exclusion of quark cores for such massive pulsars., Comment: 12 pages including 6 figures

A pure nucleonic equation of state (EoS) for beta equilibrated charge neutral neutron star (NS) matter is determined using density dependent effective NN interaction. This EoS is found to satisfy both the constraints from the observed mass-radius of neutron stars and flow data from heavy-ion collisions. Recent observations of the binary millisecond pulsar J1614-2230 by P. B. Demorest et al. [1] suggest that the masses lie within (1.97\pm 0.04) M_\odot (M_\odot, solar mass). Most EoS involving exotic matter, such as kaon condensates or hyperons, tend to predict maximum masses well below 2.0M_\odot and are therefore ruled out. We are able to reproduce the measured mass-radius relationship for rotating and static NS. We ensure that the star rotating not faster than the frequency limited by r-mode instability gives the maximum mass about 1.95M_\odot with radius about 10 kilometer., Comment: 5 pages, 2 Figures

The probability of $\alpha$ particle emission for some recently observed superheavy nuclei (SHN) are investigated. The $\alpha$-decay half lives of SHN are calculated in a quantum tunneling model with density dependent M3Y (DDM3Y) effective nuclear interaction using theoretical and measured $Q_\alpha$ values. We determine the density distribution of $\alpha$ and daughter nuclei from the relativistic mean field theory (RMF) using FSUGold force, NL3 and TM1 parameter sets. The double folded nuclear potential is numerically calculated in a more microscopic manner using these density distributions. The estimated values of $\alpha$-decay half-lives are in good agreement with the recent data. We compare our results with recently detected $\alpha$-decay chains from new element with atomic number Z=117 reported by JINR, Dubna. Finally, we determine the half-lives of superheavy elements with Z=108-120 and neutron number N=152-190 to explore the long-standing predictions on the existence of an "island of stability" due to possible spherical proton (Z$\sim 114$) and neutron (N$\sim 184$) shell closures., Comment: 4 pages, 2 figures, 2 tables

Pure hadronic compact stars, above a limiting value ($\approx$1.6 M$_\odot$) of their gravitational masses, to which predictions of most of other equations of state (EoSs) are restricted, can be reached from the equation of state (EoS) obtained using DDM3Y effective interaction. This effective interaction is found to be quite successful in providing unified description of elastic and inelastic scattering, various radioactivities and nuclear matter properties. We present a systematic study of the properties of pure hadronic compact stars. The $\beta$-equilibrated neutron star matter using this EoS with a thin crust is able to describe highly-massive compact stars, such as PSR B1516+02B with a mass M=1.94$^{+0.17}_{-0.19}$ M$_\odot$ and PSR J0751+1807 with a mass M=2.1$\pm$0.2 M$_\odot$ to a 1$\sigma$ confidence level., Comment: 5 pages, 4 figures