1,058 research outputs found

    Changes in the Internal Organizational and Administrative Practices in the Elementary School from 1945 to 1950

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    This study is designed to show what changes have been made in the organization and the administration of the elementary school from 1945 to 1950, as revealed in the literature and to point out possible trends, or indices of trends during this period. The expression or indices of trends is used because it is difficult to point out trends in elementary education in a five-year period. The elementary school is not perfect, but that it is constantly changing in an effort to improve, is becoming more evident in the field of elementary education. This writer believes that democratic society never remains constant; we are always developing the elementary school, which has made notable progress during the last half century. Local and world conditions have their influence upon education which cause the internal changes in content and administration of the elementary curriculum. Changes are made in education to stimulate the program of the School, so that it will meet the growing needs of the children during their developmental period

    BiSON data preparation: A correction for differential extinction and the weighted averaging of contemporaneous data

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    The Birmingham Solar Oscillations Network (BiSON) has provided high-quality high-cadence observations from as far back in time as 1978. These data must be calibrated from the raw observations into radial velocity and the quality of the calibration has a large impact on the signal-to-noise ratio of the final time series. The aim of this work is to maximise the potential science that can be performed with the BiSON data set by optimising the calibration procedure. To achieve better levels of signal-to-noise ratio we perform two key steps in the calibration process: we attempt a correction for terrestrial atmospheric differential extinction; and the resulting improvement in the calibration allows us to perform weighted averaging of contemporaneous data from different BiSON stations. The improvements listed produce significant improvement in the signal-to-noise ratio of the BiSON frequency-power spectrum across all frequency ranges. The reduction of noise in the power spectrum will allow future work to provide greater constraint on changes in the oscillation spectrum with solar activity. In addition, the analysis of the low-frequency region suggests we have achieved a noise level that may allow us to improve estimates of the upper limit of g-mode amplitudes.Comment: Accepted for publication in MNRAS; 10 pages, 7 figure

    Performance of the Birmingham Solar-Oscillations Network (BiSON)

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    The Birmingham Solar-Oscillations Network (BiSON) has been operating with a full complement of six stations since 1992. Over 20 years later, we look back on the network history. The meta-data from the sites have been analysed to assess performance in terms of site insolation, with a brief look at the challenges that have been encountered over the years. We explain how the international community can gain easy access to the ever-growing dataset produced by the network, and finally look to the future of the network and the potential impact of nearly 25 years of technology miniaturisation.Comment: 31 pages, 19 figures. Accepted by Solar Physics: 2015 October 20. First online: 2015 December 7. Open Acces

    The relation between Δν\Delta\nu and νmax\nu_{max} for solar-like oscillations

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    Establishing relations between global stellar parameters and asteroseismic quantities can help improve our understanding of stellar astrophysics and facilitate the interpretation of observations. We present an observed relation between the large frequency separation, Δν\Delta\nu, and the frequency of maximum power, νmax\nu_{max}. We find that Δν\Delta\nu is proportional to (νmax)0.77(\nu_{max})^0.77, allowing prediction of Δν\Delta\nu to about 15 per cent given νmax\nu_{max}. Our result is further supported by established scaling relations for Δν\Delta\nu and νmax\nu_{max} and by extended stellar model calculations, which confirm that Δν\Delta\nu can be estimated using this relation for basically any star showing solar-like oscillations in the investigated range (0.5<M/Msol<4.0).Comment: 5 pages, 8 figures, Letter accepted by MNRA

    Acoustic power absorption and enhancement generated by slow and fast MHD waves

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    We used long duration, high quality, unresolved (Sun-as-a star) observations collected by the ground based network BiSON and by the instruments GOLF and VIRGO on board the ESA/NASA SOHO satellite to search for solar-cycle-related changes in mode characteristics in velocity and continuum intensity for the frequency range between 2.5mHz < nu < 6.8mHz. Over the ascending phase of solar cycle 23 we found a suppression in the p-mode amplitudes both in the velocity and intensity data between 2.5mHz <nu< 4.5mHz with a maximum suppression for frequencies in the range between 2.5mHz <nu< 3.5mHz. The size of the amplitude suppression is 13+-2 per cent for the velocity and 9+-2 per cent for the intensity observations. Over the range 4.5mHz <nu< 5.5mHz the findings hint within the errors to a null change both in the velocity and intensity amplitudes. At still higher frequencies, in the so called High-frequency Interference Peaks (HIPs) between 5.8mHz <nu < 6.8mHz, we found an enhancement in the velocity amplitudes with the maximum 36+-7 per cent occurring for 6.3mHz <nu< 6.8mHz. However, in intensity observations we found a rather smaller enhancement of about 5+-2 per cent in the same interval. There is evidence that the frequency dependence of solar-cycle velocity amplitude changes is consistent with the theory behind the mode conversion of acoustic waves in a non-vertical magnetic field, but there are some problems with the intensity data, which may be due to the height in the solar atmosphere at which the VIRGO data are taken.Comment: Accepted for publication in A&A. 10 pages, 9 figures

    Changing the νmax\nu_{\max} Scaling Relation: The Need For a Mean Molecular Weight Term

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    The scaling relations that relate the average asteroseismic parameters Δν\Delta \nu and νmax\nu_{\max} to the global properties of stars are used quite extensively to determine stellar properties. While the Δν\Delta \nu scaling relation has been examined carefully and the deviations from the relation have been well documented, the νmax\nu_{\max} scaling relation has not been examined as extensively. In this paper we examine the νmax\nu_{\max} scaling relation using a set of stellar models constructed to have a wide range of mass, metallicity, and age. We find that as with Δν\Delta \nu, νmax\nu_{\max} does not follow the simple scaling relation. The most visible deviation is because of a mean molecular weight term and a Γ1\Gamma_1 term that are commonly ignored. The remaining deviation is more difficult to address. We find that the influence of the scaling relation errors on asteroseismically derived values of logg\log g are well within uncertainties. The influence of the errors on mass and radius estimates is small for main sequence and subgiants, but can be quite large for red giants.Comment: 15 pages, 14 figures, accepted for publication in Ap

    Parametrizing the time-variation of the "surface term" of stellar p-mode frequencies: application to helioseismic data

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    The solar-cyle variation of acoustic mode frequencies has a frequency dependence related to the inverse mode inertia. The discrepancy between model predictions and measured oscillation frequencies for solar and solar-type stellar acoustic modes includes a significant frequency-dependent term known as the surface term that is also related to the inverse mode inertia. We parametrize both the surface term and the frequency variations for low-degree solar data from Birmingham Solar-Oscillations Network (BiSON) and medium-degree data from the Global Oscillations Network Group (GONG) using the mode inertia together with cubic and inverse frequency terms. We find that for the central frequency of rotationally split multiplets the cubic term dominates both the average surface term and the temporal variation, but for the medium-degree case the inverse term improves the fit to the temporal variation. We also examine the variation of the even-order splitting coefficients for the medium-degree data and find that, as for the central frequency, the latitude-dependent frequency variation, which reflects the changing latitudinal distribution of magnetic activity over the solar cycle, can be described by the combination of a cubic and an inverse function of frequency scaled by inverse mode inertia. The results suggest that this simple parametrization could be used to assess the activity-related frequency variation in solar-like asteroseismic targets.Comment: 13 pages, 11 figures. Accepted by MNRAS 13 October 201

    Changes in the sensitivity of solar p-mode frequency shifts to activity over three solar cycles

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    Low-degree solar p-mode observations from the long-lived Birmingham Solar Oscillations Network (BiSON) stretch back further than any other single helioseismic data set. Results from BiSON have suggested that the response of the mode frequency to solar activity levels may be different in different cycles. In order to check whether such changes can also be seen at higher degrees, we compare the response of medium-degree solar p-modes to activity levels across three solar cycles using data from Big Bear Solar Observatory (BBSO), Global Oscillation Network Group (GONG), Michelson Doppler Imager (MDI) and Helioseismic and Magnetic Imager (HMI), by examining the shifts in the mode frequencies and their sensitivity to solar activity levels. We compare these shifts and sensitivities with those from radial modes from BiSON. We find that the medium-degree data show small but significant systematic differences between the cycles, with solar cycle 24 showing a frequency shift about 10 per cent larger than cycle 23 for the same change in activity as determined by the 10.7 cm radio flux. This may support the idea that there have been changes in the magnetic properties of the shallow subsurface layers of the Sun that have the strongest influence on the frequency shifts.Comment: 6 pages, 3 figures, accepted by MNRAS 3rd July 201

    Why should we correct reported pulsation frequencies for stellar line-of-sight Doppler velocity shifts?

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    In the age of Kepler and Corot, extended observations have provided estimates of stellar pulsation frequencies that have achieved new levels of precision, regularly exceeding fractional levels of a few parts in 10410^{4}. These high levels of precision now in principle exceed the point where one can ignore the Doppler shift of pulsation frequencies caused by the motion of a star relative to the observer. We present a correction for these Doppler shifts and use previously published pulsation frequencies to demonstrate the significance of the effect. We suggest that reported pulsation frequencies should be routinely corrected for stellar line-of-sight velocity Doppler shifts, or if a line-of-sight velocity estimate is not available, the frame of reference in which the frequencies are reported should be clearly stated.Comment: 5 pages, 1 figure, accepted for publication in MNRAS Letter
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