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We illustrate a method for estimating the vertical position of the Sun above the Galactic plane by $\gamma$-ray observations. Photons of $\gamma$-ray wavelengths are particularly well suited for geometrical and kinematic studies of the…

High Energy Astrophysical Phenomena · Physics 2020-01-08 Thomas Siegert

Aims: We test the reliability of the observed and calculated spectral irradiance variations between 200 and 1600 nm over a time span of three solar rotations in 2004. Methods: We compare our model calculations to spectral irradiance…

Astrophysics · Physics 2009-11-13 Yvonne C. Unruh , Natalie A. Krivova , Sami K. Solanki , Jerald W. Harder , Greg Kopp

The aim of this paper is to investigate whether there are any 11-yr or quasi-biennial solar cycle-related variations in solar rotational splitting frequencies of low-degree solar p modes. Although no 11-yr signals were observed, variations…

Solar and Stellar Astrophysics · Physics 2015-06-04 Anne-Marie Broomhall , David Salabert , William J. Chaplin , Rafael A. Garcia , Yvonne Elsworth , Rachel Howe , Savita Mathur

We study the effects of different descriptions of the solar surface convection on the eigenfrequencies of p-modes. 1-D evolution calculations of the whole Sun and 3-D hydrodynamic and magnetohydrodynamic simulations of the current surface…

Solar and Stellar Astrophysics · Physics 2015-06-17 Laurent Piau , Remo Collet , Robert F. Stein , Regner Trampedach , Pierre Morel , Sylvaine Turck-Chieze

The surface granularity of small Solar System bodies is diverse through the different types of planetary bodies and even for specific objects it is often not known in detail. One of the physical properties that strongly depends on the…

Earth and Planetary Astrophysics · Physics 2021-09-29 D. Bischoff , B. Gundlach , J. Blum

The solar corona is orders of magnitude hotter than the underlying photosphere, but how the corona attains such high temperatures is still not understood. Soft X-ray (SXR) emission provides important diagnostics for thermal processes in the…

Solar and Stellar Astrophysics · Physics 2015-09-15 Amir Caspi , Thomas N. Woods , Harry P. Warren

A method to measure the seeing from video made during drift-scan solar transits is proposed. The limb of the Sun is projected over a regular grid evenly spaced. The temporal dispersion of the time intervals among the contacts between solar…

Instrumentation and Methods for Astrophysics · Physics 2011-06-14 Costantino Sigismondi

We recalibrate a standard solar model seismologically to estimate the main-sequence age of the Sun. Our procedure differs from what we have done in the past by removing from the observed frequencies the effect of hydrogen ionization and the…

Astrophysics · Physics 2015-05-13 Günter Houdek , Douglas Gough

The aim of this work is to investigate rotation profile of solar-like stars with magnetic fields. A diffusion coefficient of magnetic angular momentum transport is deduced. Rotating stellar models with different mass are computed under the…

Astrophysics · Physics 2008-12-23 Wuming Yang , Shaolan Bi

Irradiance variability has been monitored from space for more than two decades. Even if data are coming from different sources, it is well established that a temporal variability exists which can be set to as approximately 0.1%, in phase…

Astrophysics · Physics 2009-11-11 J. P. Rozelot , S. Lefebvre , S. Pireaux , A. Ajabshirizadeh

Knowing the lengthscales at which turbulent fluctuations dissipate is key to understanding the nature of weakly compressible magnetohydrodynamic turbulence. We use radio wavelength interferometric imaging observations which measure the…

Solar and Stellar Astrophysics · Physics 2019-02-19 K. Sasikumar Raja , Prasad Subramanian , Madhusudan Ingale , R. Ramesh

We calculate precise stellar radii and surface gravities from the asteroseismic analysis of over 500 solar-type pulsating stars observed by the Kepler space telescope. These physical stellar properties are compared with those given in the…

The dependence of the cosmic ray intensity on Galactocentric distance is known to be much less rapid than that to be thought-to-be sources: supernova remnants. This is an old problem ('the radial gradient problem') which has led to a number…

Astrophysics of Galaxies · Physics 2015-12-23 Anatoly Erlykin , Arnold Wolfendale , Vladimir Dogiel

We present a novel experiment with the capacity to independently measure both the electron density and the magnetic field of the solar corona. We achieve this through measurement of the excess Faraday rotation due to propagation of the…

Astrophysics · Physics 2009-11-13 S. M. Ord , S. Johnston , J. Sarkissian

Clouds cast shadows on the surface and locally enhance solar irradiance by absorbing and scattering sunlight, resulting in fast and large solar irradiance fluctuations on the surface. Typical spatiotemporal scales and driving mechanisms of…

Atmospheric and Oceanic Physics · Physics 2023-03-09 Wouter Mol , Bart van Stratum , Wouter Knap , Chiel van Heerwaarden

Variations of frequency separations of low-degree p-modes are studied over the solar activity cycle. The separations studied are obtained from the frequencies of low-degree p-modes of the Global Oscillation Network Group (GONG). 10.7 cm…

Solar and Stellar Astrophysics · Physics 2015-05-14 Wuming Yang , Xiangcun Meng

We study how the precision of the exoplanet radius determination is affected by our present knowledge of limb darkening in two cases: when we fix the limb darkening coefficients and when we adjust them. We also investigate the effects of…

Earth and Planetary Astrophysics · Physics 2012-12-12 Sz. Csizmadia , Th. Pasternacki , C. Dreyer , J. Cabrera , A. Erikson , H. Rauer

A very slight rotation-induced latitudinal temperature variation (presumably on the order of several Kelvin) on the solar surface is theoretically expected. While recent high-precision solar brightness observations reported its detection,…

Solar and Stellar Astrophysics · Physics 2017-08-30 Y. Takeda , S. UeNo

Quantitative estimates of lensing probabilities must be self-consistent. In particular, for asymptotically isothermal models: (1) using the $(3/2)^{1/2}$ correction for the velocity dispersion overestimates the expected number of lenses by…

Astrophysics · Physics 2007-05-23 C. S. Kochanek

The Sun's spectrum varies with center-to-limb distance. This variation is governed by the underlying temperature-density structure of the solar atmosphere. To explore the spectrally resolved center-to-limb variation (CLV) we make use of two…

Solar and Stellar Astrophysics · Physics 2014-12-24 Jan Stenflo