Dynamical phasing of Type II Cepheids

In this paper we examine the problems of phasing using light curves and offer an alternate technique using the changes in acceleration to establish the zero point. We give astrophysical justification as to why this technique is useful and apply the technique to a selection of Type II Cepheids. We then examine some limitations of the technique which qualify its use.Comment: 6 pages, including 4 figures, accepted in MNRA

Fitting theories of nuclear binding energies

In developing theories of nuclear binding energy such as density-functional theory, the effort required to make a fit can be daunting due to the large number of parameters that may be in the theory and the large number of nuclei in the mass table. For theories based on the Skyrme interaction, the effort can be reduced considerably by using the singular value decomposition to reduce the size of the parameter space. We find that the sensitive parameters define a space of dimension four or so, and within this space a linear refit is adequate for a number of Skyrme parameters sets from the literature. We do not find marked differences in the quality of the fit between the SLy4, the Bky4 and SkP parameter sets. The r.m.s. residual error in even-even nuclei is about 1.5 MeV, half the value of the liquid drop model. We also discuss an alternative norm for evaluating mass fits, the Chebyshev norm. It focuses attention on the cases with the largest discrepancies between theory and experiment. We show how it works with the liquid drop model and make some applications to models based on Skyrme energy functionals. The Chebyshev norm seems to be more sensitive to new experimental data than the root-mean-square norm. The method also has the advantage that candidate improvements to the theories can be assessed with computations on smaller sets of nuclei.Comment: 17 pages and 4 figures--version encorporates referee's comment

Universal Expression for the Lowest Excitation Energy of Natural Parity Even Multipole States

We present a new expression for the energy of the lowest collective states in even-even nuclei throughout the entire periodic table. Our empirical formula is extremely valid and holds universally for all of the natural parity even multipole states. This formula depends only on the mass number and the valence nucleon numbers with six parameters. These parameters are determined easily and unambiguously from the data for each multipole state. We discuss the validity of our empirical formula by comparing our results with those of other studies and also by estimating the average and the dispersion of the logarithmic errors of the calculated excitation energies with respect to the measured ones.Comment: 10 pages, 5 figure

Empirical formula applied to the lowest excitation energies of the natural parity odd multipole states in even-even nuclei

We applied our recently proposed empirical formula, a formula quite successful in describing essential trends of the lowest excitation energies of the natural parity even multipole states, to the lowest excitation energies of the natural parity odd multipole states in even-even nuclei throughout the entire periodic table. Even though the systematic behavior of the lowest excitation energies of odd multipole states is quite different from those of even multipole states, we have shown that the same empirical formula also holds reasonably well for the odd multipole states with the exception of a few certain instances.Comment: 23 pages, 11 figure

Distance and mass of pulsating stars from multicolour photometry and atmospheric models

For determining distance and mass of pulsating stars a new, purely photometric method is described in which radial velocity observations are not needed. The method is compared with the Baade-Wesselink method. As an example the RR Lyrae variable SU Dra is given.Comment: 9 pages, 4 figures, 4 tables. Accepted in Astronomy and Astrophysic