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This work addresses a procedure to estimate fundamental stellar parameters such as T eff , logg, [Fe/H], and v sin i using a dimensionality reduction technique called Principal Component Analysis (PCA), applied to a large database of…

Solar and Stellar Astrophysics · Physics 2015-08-18 W. Farah , M. Gebran , F. Paletou , R. Blomme

Stellar seismology appears more and more as a powerful tool for a better determination of the fundamental properties of solar-type stars. However the particular case of Sun is still challenging. The helioseismic sound speed determination…

Our aim is to evaluate fundamental parameters from the analysis of the electromagnetic spectra of stars. We may use $10^3$-$10^5$ spectra; each spectrum being a vector with $10^2$-$10^4$ coordinates. We thus face the so-called "curse of…

Instrumentation and Methods for Astrophysics · Physics 2017-06-08 V. Watson , JF. Trouilhet , F. Paletou , S. Girard

For short-term solar irradiance forecasting, the traditional point forecasting methods are rendered less useful due to the non-stationary characteristic of solar power. The amount of operating reserves required to maintain reliable…

Machine Learning · Computer Science 2023-08-02 Sakshi Mishra , Praveen Palanisamy

The solar meridional flow is a crucial ingredient in modern dynamo theory. Seismic estimates of this flow have, however, been contradictory in deeper layers below about $0.9\,R_\odot$. Results from time-distance helioseismology have so far…

Solar and Stellar Astrophysics · Physics 2017-08-16 Vincent G. A. Böning , Markus Roth , Jason Jackiewicz , Shukur Kholikov

Frequencies of intermediate-degree f-modes of the Sun seem to indicate that the solar radius is smaller than what is normally used in constructing solar models. We investigate the possible consequences of an error in radius on results for…

Astrophysics · Physics 2009-10-30 Sarbani Basu

We investigate the parameters of global solar p-mode oscillations, namely damping width $\Gamma$, amplitude $A$, mean squared velocity $\langle v^2\rangle$, energy $E$, and energy supply rate $\mathrm{d}E/\mathrm{d} t$, derived from two…

Solar and Stellar Astrophysics · Physics 2018-10-23 René Kiefer , Rudi Komm , Frank Hill , Anne-Marie Broomhall , Markus Roth

This work presents a set of optimal machine learning (ML) models to represent the temporal degradation suffered by the power conversion efficiency (PCE) of polymeric organic solar cells (OSCs) with a multilayer structure…

The feature based spatial verification method SAL is applied to cloud data, i.e. two-dimensional spatial fields of total cloud cover and spectral radiance. Model output is obtained from the COSMO-DE forward operator SynSat and compared to…

Atmospheric and Oceanic Physics · Physics 2016-03-08 Michael Weniger , Petra Friederichs

A model-independent reconstruction of mechanical profiles (density, pressure) of the solar interior is outlined using the adiabatic sound speed and bouyancy frequency profiles. These can be inferred from helioseismology if both p- and…

Astrophysics · Physics 2009-10-31 Dallas C. Kennedy

We seek to address whether solar-cycle frequency shifts of the Sun's low-l p modes `distort' the underlying shapes of the mode peaks, when those peaks are observed in power frequency spectra made from data spanning large fractions, or more,…

Astrophysics · Physics 2009-11-13 W. J. Chaplin , Y. Elsworth , R. New , T. Toutain

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…

Astrophysics · Physics 2009-11-13 Chia-Hsien Lin , H. M. Antia , Sarbani Basu

Based on the Solar Standard Model we developed a solar model in hydrostatic equilibrium using two polytropes that describes both the "radiative" and "convective" zones of the solar interior. Then we apply small periodic and adiabatic…

Astrophysics · Physics 2007-05-23 G. A. Pinzon

The continuous high spatial-resolution Doppler observation of the Sun by Solar Dynamics Observatory / Helioseismic and Magnetic Imager allows us to compute helioseismic k-omega power-spectrum diagram using only oscillations inside a…

Solar and Stellar Astrophysics · Physics 2015-06-11 Junwei Zhao , Dean-Yi Chou

We compared the results from the JSOC pipeline for horizontal flow components and the perturbations of the speed of sound at set of depths with equivalent results from an independently implemented pipeline using a different time-distance…

Solar and Stellar Astrophysics · Physics 2019-09-04 David Korda , Michal Švanda , Junwei Zhao

We suggest a solution to an important problem of observational helioseismology of the separation of lines of solar acoustic (p) modes of low angular degree in oscillation power spectra by constructing optimal masks for Doppler images of the…

Astrophysics · Physics 2009-10-31 T. Toutain , A. G. Kosovichev

Here we present a detailed analysis of solar acoustic mode frequencies and their rotational splittings for modes with degree up to 900. They were obtained by applying spherical harmonic decomposition to full-disk solar images observed by…

Astrophysics · Physics 2008-08-22 M. C. Rabello-Soares , S. G. Korzennik , J. Schou

Solar oscillations consist of a rich spectrum of internal acoustic waves and surface gravity waves, stochastically excited by turbulent convection. They have been monitored almost continuously over the last ten years with high-precision…

Astrophysics · Physics 2010-11-26 L. Gizon

Hydrodynamical, 3D simulations of the outer layers of the Sun and Alpha Cen A are used to obtain constraints on the properties of turbulent convection in such stars. These constraints enable us to compute - on the base of a theoretical…

Astrophysics · Physics 2007-05-23 R. Samadi , M. J. Goupil , F. Baudin , D. Georgobiani , R. Trampedach , R. Stein , A. Nordlund