Pulsational and evolutionary analysis of the double-mode RR Lyrae star BS Com

We derive the basic physical parameters of the field double-mode RR Lyrae star BS Com from its observed periods and the requirement of consistency between the pulsational and evolutionary constraints. By using the current solar-scaled horizontal branch evolutionary models of Pietrinferni et al. (2004) and our linear non-adiabatic purely radiative pulsational models, we get M/M(Sun) = 0.698 +/- 0.004, log(L/L(Sun)) = 1.712 +/- 0.005, T(eff) = 6840 +/- 14 K, [Fe/H] = -1.67 +/- 0.01, where the errors are standard deviations assuming uniform age distribution along the full range of uncertainty in age. The last two parameters are in a good agreement with the ones derived from the observed BVIc colours and the updated ATLAS9 stellar atmosphere models. We get T(eff) = 6842 +/- 10 K, [Fe/H] = -1.58 +/- 0.11, where the errors are purely statistical ones. It is remarkable that the derived parameters are nearly independent of stellar age at early evolutionary stages. Later stages, corresponding to the evolution toward the asymptotic giant branch are most probably excluded because the required high temperatures are less likely to satisfy the constraints posed by the colours. We also show that our conclusions are only weakly sensitive to nonlinear period shifts predicted by current hydrodynamical models.Comment: Accepted for publication by MNRAS on 2008 February 01. The paper contains 4 figures and 8 table

Multi-Periodic Oscillations in Cepheids and RR Lyrae-Type Stars

Classical Cepheids and RR Lyrae-type stars are usually considered to be textbook examples of purely radial, strictly periodic pulsators. Not all the variables, however, conform to this simple picture. In this review I discuss different forms of multi-periodicity observed in Cepheids and RR Lyrae stars, including Blazhko effect and various types of radial and nonradial multi-mode oscillations.Comment: Proceedings of the 20th Stellar Pulsation Conference Series: "Impact of new instrumentation & new insights in stellar pulsations", 5-9 September 2011, Granada, Spai

Kepler photometry of RRc stars: peculiar double-mode pulsations and period doubling

We present the analysis of four first overtone RR Lyrae stars observed with the Kepler space telescope, based on data obtained over nearly 2.5 yr. All four stars are found to be multiperiodic. The strongest secondary mode with frequency f2 has an amplitude of a few mmag, 20–45 times lower than the main radial mode with frequency f1. The two oscillations have a period ratio of P2/P1 = 0.612–0.632 that cannot be reproduced by any two radial modes. Thus, the secondary mode is non-radial. Modes yielding similar period ratios have also recently been discovered in other variables of the RRc and RRd types. These objects form a homogenous group and constitute a new class of multimode RR Lyrae pulsators, analogous to a similar class of multimode classical Cepheids in the Magellanic Clouds. Because a secondary mode with P2/P1 ∼ 0.61 is found in almost every RRc and RRd star observed from space, this form of multiperiodicity must be common. In all four Kepler RRc stars studied, we find subharmonics of f2 at ∼1/2f2 and at ∼3/2f2. This is a signature of period doubling of the secondary oscillation, and is the first detection of period doubling in RRc stars. The amplitudes and phases of f2 and its subharmonics are variable on a time-scale of 10–200 d. The dominant radial mode also shows variations on the same time-scale, but with much smaller amplitude. In three Kepler RRc stars we detect additional periodicities, with amplitudes below 1 mmag, that must correspond to non-radial g-modes. Such modes never before have been observed in RR Lyrae variables

Horizontal Branch Stars: The Interplay between Observations and Theory, and Insights into the Formation of the Galaxy

We review HB stars in a broad astrophysical context, including both variable and non-variable stars. A reassessment of the Oosterhoff dichotomy is presented, which provides unprecedented detail regarding its origin and systematics. We show that the Oosterhoff dichotomy and the distribution of globular clusters (GCs) in the HB morphology-metallicity plane both exclude, with high statistical significance, the possibility that the Galactic halo may have formed from the accretion of dwarf galaxies resembling present-day Milky Way satellites such as Fornax, Sagittarius, and the LMC. A rediscussion of the second-parameter problem is presented. A technique is proposed to estimate the HB types of extragalactic GCs on the basis of integrated far-UV photometry. The relationship between the absolute V magnitude of the HB at the RR Lyrae level and metallicity, as obtained on the basis of trigonometric parallax measurements for the star RR Lyrae, is also revisited, giving a distance modulus to the LMC of (m-M)_0 = 18.44+/-0.11. RR Lyrae period change rates are studied. Finally, the conductive opacities used in evolutionary calculations of low-mass stars are investigated. [ABRIDGED]Comment: 56 pages, 22 figures. Invited review, to appear in Astrophysics and Space Scienc

Meaning in life in the Federal Republic of Germany: results of a representative survey with the Schedule for Meaning in Life Evaluation (SMiLE)

This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

Thermal monitoring of leaks of deep excavation construction

Obecnie bardzo często wykonanie fundamentów budynków wymaga realizacji głębokiego wykopu. Niekontrolowany dopływ wody gruntowej do głębokiego wykopu, przecieki jego konstrukcji oraz wywołane nimi procesy erozyjne są kluczowymi zagrożeniami dla bezpieczeństwa głębokich wykopów i budowli z nimi sąsiadujących. Ich pojawienie się może wygenerować istotne dodatkowe koszty budowy. Najskuteczniejszą metodą detekcji przecieków w hydrotechnice i obudowy głębokich wykopów jest metoda termomonitoringu [ICOLD 2013]. Metoda ta została zweryfikowana i z powodzeniem jest stosowana od ponad dwudziestu lat na zachodzie Europy. W ostatnich latach wprowadzana jest do użytku w Polsce [Radzicki i in. 2015]. W artykule opisano problem niekontrolowanego dopływu wody gruntowej do głębokiego wykopu. Omówiono schemat prac przy wykonaniu ścian szczelinowych oraz typowe przyczyny ich nieszczelności. Na podstawie swoich doświadczeń zawodowych autorzy przedstawili metodę termomonitoringu oraz możliwości jej wykorzystania do lokalizacji nieszczelności obudowy wykopu przed jego wykonaniem. Przedstawiono również przykład aplikacji tej metody do detekcji przecieków konstrukcji jednej ze stacji metra w Europie.The aim of this study was to analyse the results of comparative tests on compaction parameters - maximum bulk density of dry soil (pds) and optimum moisture (wopt), by Polish standards of previous edition: PN-88/B-04481:1988 and a new edition: PN-EN 13286-2:2010. The study was performed on two non-cohesive, uniform soils sandy gravel Po (fgrSa) and medium sand Ps (fgrmgrSa) with the use of four methods (I, II, III, IV) in compliance with PN-88/B-04481:1988 and four other methods (A+A, A+B, B+A, B+B) in compliance with EN 13286-2:2010. The maximum volume of the bulk density of dry soil (pds) obtained by the procedures under both standards differ little from each other: by about 2.0-4.0% in sandy gravel and about 1.6-2.1% in medium sand. The values of optimum moisture (wopt) are not subject to any clear patterns

Thermal monitoring of leaks and internal erosion for analysis of deep excavation and damming structures

Increased seepage processes, including leaks and resulting internal erosion processes, are among the main threats to the safety of dams and levees and to the safety of deep excavations and nearby buildings. These processes can significantly affect the cost of exploitation of damming structures and the costs of construction of underground parts of buildings. One of the basic methods currently used indetecting and analysing these processes is the thermal monitoring method. This method has been used successfully for several decades, particularly in Western Europe and has evolved substantially in the last decade. Currently it is being implemented in pilot applications in Poland. The paper describes the risks and consequences of leaks and internal erosion processes for a damming structure and deep excavation. The authors present the basic issues concerning the method of thermal monitoring based on their professional experience in numerous applications of thermal monitoring methods in both hydraulic engineering and geotechnics. The paper shows examples of thermal monitoring application in the analysis of dams and deep excavations

Analysis of the possibility of detection of uncontrolled groundwater inflow into a deep excavation

The paper shows a comprehensive analysis of uncontrolled groundwater flow into a deep excavation. The scheme of works performed to construct the diaphgram walls as well as typical causes ofleakage are discussed. The possible ways of locating the lining leakage before executing the foundation with use of water-level change measurements and the thermal monitoring method are presented. In the presented calculations, the analysis of the transient heat flow and filtration coupled process was used. Numerical calculations in the case of leakage occurrence in the lining or in the foundation bottom as well as comparative calculations for the construction without the leakage were conducted. The temperature changes occurring in the diaphgram wall constructed in the ground as a result of hydration process were calculated. Then, the heat spreading as a result of waterflow through the leaky parts of the construction was analyzed. The article endeds with the conclusions and suggestion of the following work direction