It has been shown in the literature that the task of estimating the parameters of nonlinear models may be tackled with optimization heuristics. Thus, we attempt to carry these intuitions over to the estimation procedure of smooth transition autoregressive (STAR, Teräsvirta, 1994) models by introducing the following three stochastic optimization algorithms: Simulated Annealing, (Kirkpatrick, Gel...

We investigate the dependences of galaxy star-formation history and galaxy morphology on environment, using color and Hα equivalent width as starformation history indicators, using concentration and central surface brightness as morphological indicators, and using clustocentric distance as an environment indicator. Clustocentric distance has the virtue that it can be measured with very high pre...

Multiwavelength observations of isolated neutron stars as a tool to probe the properties of their surfaces ABSTRACT We show that an analysis of multiwavelength observations of isolated neutron stars based on neutron star atmosphere models can be used not only to evaluate the neutron star effective temperature, but also to determine chemical composition of its surface. To demonstrate how this ne...

We compare the Si and C isotopic data of presolar SiC grains with predictions of AGB star models computed with a wide range of input parameters The models con rm an AGB star origin for SiC grains of type mainstream Y and Z Cool bottom processing during the AGB phase is required to explain simultaneously the Si and C data for Z grains The Z grain data together with the new models indicate that t...

Modeling the dynamics of the quantum fluids within a spinning down neutron star gives a description consistent with observed pul-sar magnetic field evolution and spin-period " glitches. " The long-standing problem of large predicted excesses in spin-down sustained pulsar heating from such models now seems resolvable. However, the origin of some pulsar spin-period and pulse-shape modulations whi...

We study the motion of stars in a star cluster which revolves in a circular orbit about its parent galaxy. The star cluster is modelled as an ellipsoid of uniform spatial density. We exhibit two 2-parameter families of self-consistent equilibrium models in which the velocity at each point is confined to a line in velocity space. We exhibit the link between this problem and that of a uniform rot...

Radial pulsations of neutron stars and strange quark stars with nuclear crust are studied. The avoided crossing phenomenon occurring for the radial modes is found and discussed. Neutron star models are constructed using a realistic equation of state of dense matter and strange star models using a phenomenological bag model of quark matter. The eigenfrequencies of the three lowest modes of linea...

After a brief summary of neutron star cooling theory I present results which emphasize the importance of baryon pairing in the neutron star core. I show how the thermal evolution may be totally controlled by pairing for models which include only nucleons and models containing also hyperons. Finally, I consider the thermal evolution of ultramagnetized neutron stars whose existence has been infer...