相关论文: A homogeneous aa index: 1. Secular variation
The gravitational interaction between two objects on similar orbits can effect noticeable changes in the orbital evolution even if the ratio of their masses to that of the central body is vanishingly small. Christou (2005) observed an…
The historical record of sunspot areas is a valuable and widely used proxy of solar activity and variability. The Royal Greenwich Observatory (RGO) regularly measured this and other parameters between 1874 and 1976. After that time records…
Geomagnetic secular acceleration is a unique window on the dynamics taking place in Earth's core. In this study, the behaviours of the secular acceleration and underlying core dynamics are examined in new numerical simulations of the…
The inclination $I$ of an Earth's satellite in polar orbit undergoes a secular De Sitter precession of $-7.6$ milliarcseconds per year for a suitable choice of the initial value of its non-circulating node $\Omega$. The competing…
The Arctic and Antarctic Oscillations (AO and AAO indices) are studied using the Hamiltonian distributed chaos approach. Using the daily data (AO since 1950y and AAO since 1979y) it is shown that the power spectra of the both AO and AAO…
Recent developments in instrumentation (e.g., in particular the Kepler and CoRoT satellites) provide a new opportunity to improve the models of stellar pulsations. Surface layers, rotation, and magnetic fields imprint erratic frequency…
We report here multi-epoch, multi-frequency observations of the circular polarization in Sagittarius A*, the compact radio source in the Galactic Center. Data taken from the VLA archive indicate that the fractional circular polarization at…
Statistical methods are required to evaluate and quantify the uncertainty in environmental processes, such as land and sea surface temperature, in a changing climate. Typically, annual harmonics are used to characterize the variation in the…
We investigate the secular evolution of the orbital semi-major axis and eccentricity due to mass transfer in eccentric binaries, assuming conservation of total system mass and orbital angular momentum. Assuming a delta function mass…
Existing methods for diagnosing predictability in climate indices often make a number of unjustified assumptions about the climate system that can lead to misleading conclusions. We present a flexible family of state-space models capable of…
We present an assessment of the accuracy of the calibration measurements and atomic physics models that go into calculating the SDO/AIA response as a function of wavelength and temperature. The wavelength response is tested by convolving…
The journey of the Sun through space carries the solar system through a dynamic interstellar environment that is presently characterized by Mach 1 motion between the heliosphere and the surrounding interstellar medium (ISM). The interaction…
Motivated by the various examples of spatial variability in the power of the acoustic spectrum, we attempted to look for spatial variability in the peak frequency of the spectrum. However, the determination of this peak frequency on a…
We give an overview of the current understanding of Type Ia supernovae relevant for their use as cosmological distance indicators. We present the physical basis to understand their homogeneity of the observed light curves and spectra and…
Four different data sets pertaining to the neutral atom environment at 1 AU are presented and discussed. These data sets include neutral solar wind and interstellar neutral atom data from IMAGE/LENA, energetic hydrogen atom data from…
Recent downward revision of solar heavy-element abundances using three-dimensional atmospheric model has introduced serious discrepancies between standard solar models and helioseismic inferences about solar structure. In this paper, we…
Spatial heteroskedasticity refers to stochastically changing variances and covariances in space. Such features have been observed in, for example, air pollution and vegetation data. We study how volatility modulated moving averages can…
Aperiodic variability is a characteristic feature of young stars, massive stars, and active galactic nuclei. With the recent proliferation of time domain surveys, it is increasingly essential to develop methods to quantify and analyze…
The dynamical evolution of the solar system is chaotic with a Lyapunov time of only $\sim$5 Myr for the inner planets. Due to the chaos it is fundamentally impossible to accurately predict the solar system's orbital evolution beyond…
The Generalized Cosmological Time (GCT) framework interprets the observed time dilation in Type Ia supernovae (SNe Ia) as a manifestation of a generalized lapse function in the background metric, favoring a parameter value b \approx 0.04.…