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Related papers: Source depth for solar p-modes

200 papers

High frequency acoustic waves have been suggested as a source of mechanical heating in the chromosphere. In this work the radial component of waves in the frequency interval 22mHz to 1mHz are investigated. Observations were performed using…

Astrophysics · Physics 2008-11-07 Aleksandra Andic

Polarisation measurements of solar flares at millimetre-waves were used to investigate the magnetic field configuration of the emitting sources. We analyse two solar flares (SOL2013-02-17 and SOL2013-11-05) observed by the POlarisation…

Solar and Stellar Astrophysics · Physics 2020-05-05 Douglas F. da Silva , Paulo J. A. Simões , R. F. Hidalgo Ramírez , Adriana Válio

We present an alternative estimate of the unresolved point source contribution to the WMAP temperature power spectrum based on current knowledge of sources from radio surveys in the 1.4-90 GHz range. We implement a stochastic extrapolation…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Loris P. L. Colombo , Elena Pierpaoli

Kepler short-cadence photometry of 2347 stars with effective temperatures in the range 6000-10000 K was used to search for the presence of solar-like oscillations. The aim is to establish the location of the hot end of the stochastic…

Solar and Stellar Astrophysics · Physics 2020-08-17 L. A. Balona

Inverter-based solar energy sources are becoming widely integrated into modern power systems. However, their impacts on the system in the frequency domain are rarely investigated at a higher frequency range than conventional…

Signal Processing · Electrical Eng. & Systems 2022-02-24 Chen Wang , Luigi Vanfretti , Chetan Mishra , Kevin D. Jones , R. Matthew Gardner

We report results of pentachromatic VLBI survey for 18 GHz-peaked spectrum sources. Spectral fitting at every pixel across five frequencies allows us to illustrate distribution of optical depth in terms of free-free absorption or…

Astrophysics · Physics 2007-05-23 S. Kameno , M. Inoue , Z. -Q. Shen , S. Sawada-Satoh , K. Wajima

Analyses of a 3D simulation of the upper layers of a solar convective envelope provide constraints on the physical quantities which enter the theoretical formulation of a stochastic excitation model of solar p modes, for instance the…

Astrophysics · Physics 2009-11-07 R. Samadi , A. Nordlund , R. F. Stein , M. J. Goupil , I. Roxburgh

The umbral regions of sunspots and pores in the solar photosphere are generally dominated by $3$~mHz oscillations, which are due to $p$-modes penetrating the magnetic region. In these locations, wave power is also significantly reduced with…

We present high sensitivity polarimetric observations in 6 bands covering the 5.5-38 GHz range of a complete sample of 53 compact extragalactic radio sources brighter than 200 mJy at 20 GHz. The observations, carried out with the Australia…

The success of helioseismology is due to its capability to accurately measure the p-mode parameters of the solar eigenmode spectrum, which allow us to infer unique information about the internal structure and dynamics of the Sun. It also…

Solar and Stellar Astrophysics · Physics 2011-10-14 D. Salabert

We have used 4752 days of data collected by the Birmingham Solar-Oscillations Network (BiSON) to determine very precise oscillation frequencies of acoustic low-degree modes that probe the solar core. We compare the fine (small frequency)…

We present the statistical analysis of the spectral response of solar radio type III bursts over the wide frequency range between 20 kHz and 410 MHz. For this purpose, we have used observations that were carried out using both spaced-based…

The excitation rate P of solar p-modes is computed with a model of stochatic excitation which involves constraints on the averaged properties of the solar turbulence. These constraints are obtained from a 3D simulation. Resulting values for…

Astrophysics · Physics 2007-05-23 R. Samadi , M. J. Goupil , Y. Lebreton , A. Nordlund , F. Baudin

In the solar convection zone acoustic waves are scattered by turbulent sound speed fluctuations. In this paper the scattering of waves by convective cells is treated using Rytov's technique. Particular care is taken to include diffraction…

Astrophysics · Physics 2009-10-31 M. Brüggen

Extreme precision radial-velocity spectrometers enable extreme precision stellar spectroscopy. Searches for low-mass exoplanets around solar-type stars are limited by the physical variability in stellar spectra, such as the short-term…

Solar and Stellar Astrophysics · Physics 2023-11-01 Dainis Dravins , Hans-Günter Ludwig

We present a three epoch survey for transient and variables in the extended Chandra Deep Field South at 5.5 GHz with the Australia Telescope Compact Array. A region covering $\sim$0.3 deg$^{2}$ was observed on timescales of 2.5 months and…

Astrophysics of Galaxies · Physics 2015-06-17 M. E. Bell , M. T. Huynh , P. Hancock , Tara Murphy , B. M. Gaensler , D. Burlon , C. Trott , K. Bannister

We review estimates of small scale fluctuations due to extragalactic point sources in the Planck Surveyor frequency bands. While our undestanding of the spectral and evolutionary properties of these sources is far from complete,…

Astrophysics · Physics 2007-05-23 G. De Zotti , L. Toffolatti , G. L. Granato

We present comparison of numerical simulations of propagation of MHD waves,excited by subphotospheric perturbations, in two different ("deep" and "shallow") magnetostatic models of the sunspots. The "deep" sunspot model distorts both the…

Solar and Stellar Astrophysics · Physics 2016-09-08 K. Parchevsky , A. Kosovichev , E. Khomenko , V. Olshevsky , M. Collados

We present observational evidence of compressible magnetohydrodynamic wave modes propagating from the solar photosphere through to the base of the transition region in a solar magnetic pore. High cadence images were obtained simultaneously…

We used the m-averaged spectrum technique ("collapsogram") to extract the low-frequency solar p-mode parameters of low- and intermediate-angular degrees (l \leq 35) in long time series of GONG and MDI observations. Rotational splittings and…

Astrophysics · Physics 2008-11-12 D. Salabert , A. Eff-Darwich , R. Howe , S. G. Korzennik