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  • Context. The Sun and solar-like stars undergo activity cycles for which the underlying mechanisms are not well understood. The oscillations of the Sun are known to vary with activity cycle and these changes provide diagnostics on the conditions below the photosphere. Kepler has detected oscillations in hundreds of solar-like stars but as of yet, no widespread detection of signatures of magnetic activity cycles in the oscillation parameters of these stars have been reported. Aims. We analyse the photometric short cadence Kepler time series of a set of 24 solar-like stars, which were observed for at least 960 days each, with the aim to find signatures of stellar magnetic activity in the oscillation parameters. Methods. We analyse the temporal evolution of oscillation parameters by measuring mode frequency shifts and changes in the height of the p-mode envelope. Results. For 22 of the 24 investigated stars, we find significant frequency shifts in time, indicating stellar magnetic activity. For the most prominent example, KIC 8006161, we find that, similar to the solar case, frequency shifts are smallest for the lowest and largest for the highest p-mode frequencies. Conclusions. These findings show that magnetic activity can be routinely observed in the oscillation parameters for solar-like stars. The large proportion of stars for which this is the case opens up the possibility to place the Sun and its activity cycle in the context of other stars.
    Data Types:
    • Video
  • The detection and analysis of oscillations in binary star systems is critical in understanding stellar structure and evolution. This is because such systems have the same initial chemical composition and age. Solar-like oscillations have been detected in both components of the asteroseismic binary HD 176465 by Kepler (White et al., 2016). This study presents an independent modelling of the two stars in this binary system. Stellar models generated using MESA (Modules for Experiment in Stellar Astrophysics) were fitted to both the observed individual frequencies and some spectroscopic parameters. The individual theoretical oscillation frequencies for the corresponding stellar models were obtained using GYRE as the pulsation code. A Bayesian approach was applied to find the Probability Distribution Functions of the stellar parameters using AIMS (Asteroseismic Inference on Massive Scale) as the optimization code. The age of the individual stars was found to agree with that obtained by White et al., (2016) of about 3.0 $\pm$ 0.5 Gyr old.
    Data Types:
    • Video
  • The frequency condition for the mixed modes of nonradial stellar oscillations is generally examined by a simple physical model based on a running-wave picture. The coupling coefficient between the gravity-wave oscillation in the core and the acoustic-wave oscillation in the envelope is expressed in terms of the reflection coefficient at the intermediate evanescent region. It is also argued that the eigenmode condition should appropriately be modified if the wave generated near the surface and transmitted to the core is (partially) lost either by damping or scattering in the core. The derived formulae should be helpful in understanding the physics of the mixed modes in general, the origin of the red giants with depressed dipolar modes, and the effect of radiative damping in the core of the red giant stars.
    Data Types:
    • Video
  • The detection and analysis of oscillations in binary star systems is critical in understanding stellar structure and evolution. This is because such systems have the same initial chemical composition and age. Solar-like oscillations have been detected in both components of the asteroseismic binary HD 176465 by Kepler (White et al., 2016). This study presents an independent modelling of the two stars in this binary system. Stellar models generated using MESA (Modules for Experiment in Stellar Astrophysics) were fitted to both the observed individual frequencies and some spectroscopic parameters. The individual theoretical oscillation frequencies for the corresponding stellar models were obtained using GYRE as the pulsation code. A Bayesian approach was applied to find the Probability Distribution Functions of the stellar parameters using AIMS (Asteroseismic Inference on Massive Scale) as the optimization code. The age of the individual stars was found to agree with that obtained by White et al., (2016) of about 3.0 $\pm$ 0.5 Gyr old.
    Data Types:
    • Video
  • Several hundred stars were observed in the short cadence mode of the Kepler satellite during the nominal mission phase. This generated a large pool of data which can provide insight into the characteristics of stellar activity cycles of solar-type stars through the methods of asteroseismology. From helioseismology it is known that the frequencies of solar acoustic oscillations (p modes) are positively correlated with the solar magnetic activity cycle. Evidence for a similar behaviour in the p modes of a star, which was observed by the CoRoT satellite, was provided by [1]. This showed that it is feasible to trace activity cycles of stars in their p mode frequencies. We analyse the Kepler time series of a set of solar-type stars with the aim to find signatures of stellar magnetic activity. We divide the time series of each star into shorter sub-series in order to analyse the temporal evolution of the p mode frequencies. The sub-series’ periodograms are cross-correlated to retrieve the shift of p mode frequencies over time. The errors on the shifts are computed by a resampling approach of the periodogram. We find significant frequency shifts, indicating stellar magnetic activity, for all stars we investigated. For the most prominent example, KIC 8006161, we find that, not unlike in the solar case, frequency shifts are smallest for the lowest and largest for the highest p mode frequencies.
    Data Types:
    • Video
  • The differences between the oscillation frequencies and uncertainty estimates of a star derived by different fitters can be large, sufficiently large so that, were one to find a stellar model that fitted one frequency set ($\chi^2\sim 1$), it does not fit an alternative set. I give 21 examples, comparing frequency sets in common between the Kepler Legacy project and frequency sets from Appourchaux et al (2014) and Davies et al (2015). For 16CygA\andB the differences are large; the $\chi^2$ of the fit of Legacy to Davies's values ranging from 1.64 to 11.47 for 16CygA and 1.62 to 1.79 for 16CygB, depending on which error estimates are used. I analyse both stars in some detail applying my own mode fitting code to both the Legacy and Davies's power spectra and find reasonable agreement with Davies's full frequency sets and very good agreement between values for modes with signal/noise > 1 ($\chi^2 = 0.06, \chi^2_B=0.03$). But the difference with the Legacy values remains large even for modes with S/N>1. I also examine the effects of different power spectra (weighted and unweighted) using the kasoc light curves for Q6-17.2 and Q7-Q16, the effect of different mode height ratios and different rotational splitting and inclination.
    Data Types:
    • Video
  • Ammonium acetate and ammonium chloride are the white crystalline solid inorganic compounds having wide application in synthesis and analytical chemistry. The aim of present study was to evaluate the impact of biofield treatment on spectral properties of inorganic salt like ammonium acetate and ammonium chloride. The study was performed in two groups of each compound i.e., control and treatment. Treatment groups were received Mr. Trivedi’s biofield treatment. Subsequently, control and treated groups were evaluated using Fourier Transform Infrared (FT-IR) and Ultraviolet-Visible (UV-Vis) spectroscopy. FT-IR spectrum of treated ammonium acetate showed the shifting in wavenumber of vibrational peaks with respect to control. Like, the N-H stretching was shifted from 3024-3586 cm-1 to 3033-3606 cm-1, C-H stretching from 2826-2893 cm-1 to 2817-2881 cm-1, C=O asymmetrical stretching from 1660-1702 cm-1 to 1680-1714 cm-1, N-H bending from 1533-1563 cm-1 to 1506-1556 cm-1 etc. Treated ammonium chloride showed the shifting in IR frequency of three distinct oscillation modes in NH4 ion i.e., at ν1, 3010 cm-1 to 3029 cm-1; ν2, 1724 cm-1 to 1741 cm-1; and ν3, 3156 cm-1 to 3124 cm-1. The N-Cl stretching was also shifted to downstream region i.e., from 710 cm-1 to 665 cm-1 in treated ammonium chloride. UV spectrum of treated ammonium acetate showed the absorbance maxima (λmax) at 258.0 nm that was shifted to 221.4 nm in treated sample. UV spectrum of control ammonium chloride exhibited two absorbance maxima (λmax) i.e., at 234.6 and 292.6 nm, which were shifted to 224.1 and 302.8 nm, respectively in treated sample. Overall, FT-IR and UV data of both compounds suggest an impact of biofield treatment on atomic level i.e., at force constant, bond strength, dipole moments and electron transition energy between two orbitals of treated compounds as compared to respective control.
    Data Types:
    • Document
  • Ammonium acetate and ammonium chloride are the white crystalline solid inorganic compounds having wide application in synthesis and analytical chemistry. The aim of present study was to evaluate the impact of biofield treatment on spectral properties of inorganic salt like ammonium acetate and ammonium chloride. The study was performed in two groups of each compound i.e., control and treatment. Treatment groups were received Mr. Trivedi’s biofield treatment. Subsequently, control and treated groups were evaluated using Fourier Transform Infrared (FT-IR) and Ultraviolet-Visible (UV-Vis) spectroscopy. FT-IR spectrum of treated ammonium acetate showed the shifting in wavenumber of vibrational peaks with respect to control. Like, the N-H stretching was shifted from 3024-3586 cm-1 to 3033-3606 cm-1, C-H stretching from 2826-2893 cm-1 to 2817-2881 cm-1, C=O asymmetrical stretching from 1660-1702 cm-1 to 1680-1714 cm-1, N-H bending from 1533-1563 cm-1 to 1506-1556 cm-1 etc. Treated ammonium chloride showed the shifting in IR frequency of three distinct oscillation modes in NH4 ion i.e., at ν1, 3010 cm-1 to 3029 cm-1; ν2, 1724 cm-1 to 1741 cm-1; and ν3, 3156 cm-1 to 3124 cm-1. The N-Cl stretching was also shifted to downstream region i.e., from 710 cm-1 to 665 cm-1 in treated ammonium chloride. UV spectrum of treated ammonium acetate showed the absorbance maxima (λmax) at 258.0 nm that was shifted to 221.4 nm in treated sample. UV spectrum of control ammonium chloride exhibited two absorbance maxima (λmax) i.e., at 234.6 and 292.6 nm, which were shifted to 224.1 and 302.8 nm, respectively in treated sample. Overall, FT-IR and UV data of both compounds suggest an impact of biofield treatment on atomic level i.e., at force constant, bond strength, dipole moments and electron transition energy between two orbitals of treated compounds as compared to respective control.
    Data Types:
    • Document
  • Ammonium acetate and ammonium chloride are the white crystalline solid inorganic compounds having wide application in synthesis and analytical chemistry. The aim of present study was to evaluate the impact of biofield treatment on spectral properties of inorganic salt like ammonium acetate and ammonium chloride. The study was performed in two groups of each compound i.e., control and treatment. Treatment groups were received Mr. Trivedi’s biofield treatment. Subsequently, control and treated groups were evaluated using Fourier Transform Infrared (FT-IR) and Ultraviolet-Visible (UV-Vis) spectroscopy. FT-IR spectrum of treated ammonium acetate showed the shifting in wavenumber of vibrational peaks with respect to control. Like, the N-H stretching was shifted from 3024-3586 cm-1 to 3033-3606 cm-1, C-H stretching from 2826-2893 cm-1 to 2817-2881 cm-1, C=O asymmetrical stretching from 1660-1702 cm-1 to 1680-1714 cm-1, N-H bending from 1533-1563 cm-1 to 1506-1556 cm-1 etc. Treated ammonium chloride showed the shifting in IR frequency of three distinct oscillation modes in NH4 ion i.e., at ν1, 3010 cm-1 to 3029 cm-1; ν2, 1724 cm-1 to 1741 cm-1; and ν3, 3156 cm-1 to 3124 cm-1. The N-Cl stretching was also shifted to downstream region i.e., from 710 cm-1 to 665 cm-1 in treated ammonium chloride. UV spectrum of treated ammonium acetate showed the absorbance maxima (λmax) at 258.0 nm that was shifted to 221.4 nm in treated sample. UV spectrum of control ammonium chloride exhibited two absorbance maxima (λmax) i.e., at 234.6 and 292.6 nm, which were shifted to 224.1 and 302.8 nm, respectively in treated sample. Overall, FT-IR and UV data of both compounds suggest an impact of biofield treatment on atomic level i.e., at force constant, bond strength, dipole moments and electron transition energy between two orbitals of treated compounds as compared to respective control.
    Data Types:
    • Document
  • Ammonium acetate and ammonium chloride are the white crystalline solid inorganic compounds having wide application in synthesis and analytical chemistry. The aim of present study was to evaluate the impact of biofield treatment on spectral properties of inorganic salt like ammonium acetate and ammonium chloride. The study was performed in two groups of each compound i.e., control and treatment. Treatment groups were received Mr. Trivedi’s biofield treatment. Subsequently, control and treated groups were evaluated using Fourier Transform Infrared (FT-IR) and Ultraviolet-Visible (UV-Vis) spectroscopy. FT-IR spectrum of treated ammonium acetate showed the shifting in wavenumber of vibrational peaks with respect to control. Like, the N-H stretching was shifted from 3024-3586 cm-1 to 3033-3606 cm-1, C-H stretching from 2826-2893 cm-1 to 2817-2881 cm-1, C=O asymmetrical stretching from 1660-1702 cm-1 to 1680-1714 cm-1, N-H bending from 1533-1563 cm-1 to 1506-1556 cm-1 etc. Treated ammonium chloride showed the shifting in IR frequency of three distinct oscillation modes in NH4 ion i.e., at ν1, 3010 cm-1 to 3029 cm-1; ν2, 1724 cm-1 to 1741 cm-1; and ν3, 3156 cm-1 to 3124 cm-1. The N-Cl stretching was also shifted to downstream region i.e., from 710 cm-1 to 665 cm-1 in treated ammonium chloride. UV spectrum of treated ammonium acetate showed the absorbance maxima (λmax) at 258.0 nm that was shifted to 221.4 nm in treated sample. UV spectrum of control ammonium chloride exhibited two absorbance maxima (λmax) i.e., at 234.6 and 292.6 nm, which were shifted to 224.1 and 302.8 nm, respectively in treated sample. Overall, FT-IR and UV data of both compounds suggest an impact of biofield treatment on atomic level i.e., at force constant, bond strength, dipole moments and electron transition energy between two orbitals of treated compounds as compared to respective control.
    Data Types:
    • Document