Fundamental parameters of RR Lyrae stars from multicolour photometry and Kurucz atmospheric models -- II. Adaptation to double-mode stars

Our photometric-hydrodynamic method is generalized to determine fundamental parameters of multiperiodic radially pulsating stars. We report 302 UBV(RI)_C Johnson-Kron-Cousins observations of GSC 4868-0831. Using these and published photometric data of V372 Ser, their metallicity, reddening, distance, mass, radius, equilibrium luminosity, effective temperature are determined. The results underline the necessity of using multicolour photometry including an ultraviolet band to classify properly subgroups of RR Lyrae stars: our U observations could reveal that GSC 4868-0831 is a subgiant star pulsating in two radial modes, V372 Ser is a giant star with size and mass of an RRd star.Comment: 10 pages, 4 figures, 5 tables. Accepted for publication in Monthly Notices RA

Fundamental parameters of RR Lyrae stars from multicolour photometry and Kurucz atmospheric models -- III. SW And, DH Peg, CU Com, DY Peg

We report the most comprehensive UBV(RI)_C observations of the bright, radially pulsating field stars SW And, DH Peg, CU Com, DY Peg. Long term variation has been found in the ultraviolet colour curves of SW And and DH Peg. We apply our photometric-hydrodynamic method to determine the fundamental parameters of these stars: metallicity, reddening, distance, mass, radius, equilibrium luminosity and effective temperature. Our method works well for SW And, CU Com and DY Peg. A very small mass 0.26+/-0.04 M_Sun of SW And has been found. The fundamental parameters of CU Com are those of a normal double-mode RR Lyrae (RRd) star. DY Peg has been found to have paradoxical astrophysical parameters: the metallicity, mass and period are characteristic for a high-amplitude Delta Sct star while the luminosity and radius place it in the group of RR Lyrae stars. DH Peg has been found to be peculiar: the definite instability in the colour curves towards ultraviolet, the dynamical variability of the atmosphere during the shocked phases suggests that the main assumptions of our photometric-hydrodynamic method, the quasi-static atmosphere approximation (QSAA) and the exclusive excitation of radial modes are probably not satisfied in this star. The fundamental parameters of all stars studied in this series of papers are summarized in tabular and graphical form.Comment: 15 pages, 10 figures; accepted for publication in MNRA

Phase Separation of Superfluids in the Chain of Four-Component Ultracold Atoms

We investigate the competition of various exotic superfluid states in a chain of spin-polarized ultracold fermionic atoms with hyperfine spin $F = 3/2$ and s-wave contact interactions. We show that the ground state is an exotic inhomogeneous mixture in which two distinct superfluid phases --- spin-carrying pairs and singlet quartets --- form alternating domains in an extended region of the parameter space

On the dimerized phase in the cross-coupled antiferromagnetic spin ladder

We revisit the phase diagram of the frustrated s=1/2 spin ladder with antiferromagnetic rung and diagonal couplings. In particular, we reexamine the evidence for the columnar dimer phase, which has been predicted from analytic treatment of the model and has been claimed to be found in numerical calculations. By considering longer chains and by keeping more states than in previous work using the density-matrix renormalization group, we show that the numerical evidence presented previously for the existence of the dimerized phase is not unambiguous in view of the present more careful analysis. While we cannot completely rule out the possibility of a dimerized phase in the cross-coupled ladder, we do set limits on the maximum possible value of the dimer order parameter that are much smaller than those found previously.Comment: 6 pages, 7 figure

Five colour photometry of the RRd star V372 Ser

The first UBV(RI)_C time series photometry of the RRd star V372 Ser is presented to determine some parameters of the star. In April, May 2007 2812 U, B, V, R_C, I_C frames were obtained at Konkoly and Teide Observatories, 1508 V observations were collected from the literature. Fourier fitted light curves have been derived in all bands. The non-linearly coupled frequencies f_0=(2.121840+/-.000001) c/day, f_1=(2.851188+/-.000001) c/d, i.e. periods P_0=0.4712891+/-.0000002 days, P_1=0.3507310+/-.0000001 d, P_1/P_0=0.7441950, amplitudes A_0(V)=0.15399 mag, A_1(V)=0.20591 mag, and phases have been found. A_1/A_0=1.319+/-.008 has been found from averaging the amplitude ratio in the different bands i.e. the first overtone is the dominant pulsation mode. From the V observations upper limits are given for secular change of the Fourier parameters. The period ratio and period put V372 Ser among the RRd stars of the globular clusters M3 and IC 4499, mass, luminosity, and metallicity estimates are given.Comment: accepted by Astronomy and Astrophysics (5 pages, 3 figures, 4 tables

Emergence of Quintet Superfluidity in the Chain of Partially Polarized Spin-3/2 Ultracold Atom

The system of ultracold atoms with hyperfine spin $F=3/2$ might be unstable against the formation of quintet pairs if the interaction is attractive in the quintet channel. We have investigated the behavior of correlation functions in a model including only s-wave interactions at quarter filling by large-scale density-matrix renormalization-group simulations. We show that the correlations of quintet pairs become quasi-long-ranged, when the system is partially polarized, leading to the emergence of various mixed superfluid phases in which BCS-like pairs carrying different magnetic moment coexist.Comment: 4 pages, 4 figures; significantly rewritten compared to the first versio

NON-TECTONIC SYSTEMS: CURVED STRUCTURES VAULTS, DOMES AND BARREL-VAULTS

Our present study - the concluding fifth in the series of articles to introduce the non- tectonic systems and the first to extend research into the field of the curved structures - expounds the methodology of how to connect in practice the adaptation of vaults, domes and barrel-vaults with the non-tectonic building methods on the industrial level. It is evident that the non-tectonic building, already by virtue of its universality, cannot give up using forms of spaces which enrich architecture in any case, but it is also evident that it cannot renounce the standpoints of industrialization of building either. The non-tectonic systems are based on the recognition that tectonics is not the only possible axiom of building and the adaptation of curved structures gives a further proof that such an axiomatic change is realizable and that we may open new hitherto unknown ways of industrialization of building if we break with the axiom of tectonics