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We present results using the AutoClass analysis application available at NASA/Ames Intelligent Systems Div. (2002) which is a Bayesian, finite mixture model classification system developed by Cheeseman and Stutz (1996). We apply this system…

Solar and Stellar Astrophysics · Physics 2015-05-14 R. K. Ulrich , D. Parker , L. Bertello , J. Boyden

CONTEXT: Spectral-line asymmetries and wavelength shifts are signatures of hydrodynamics in solar and stellar atmospheres. Theory may precisely predict idealized lines, but observed spectra are limited by blends, too few suitable lines,…

Astrophysics · Physics 2009-11-13 Dainis Dravins

Recent revisions of the determination of the solar composition have resulted in solar models in marked disagreement with helioseismic inferences. The effect of the composition change on the model is largely caused by the change in the…

The statistical equilibrium of neutral and ionised silicon in the solar photosphere is investigated. Line formation is discussed and the solar silicon abundance determined. High-resolution solar spectra were used to determine solar $\log…

Astrophysics · Physics 2009-11-13 J. R. Shi , T. Gehren , K. Butler , L. I. Mashonkina , G. Zhao

Ground-based spectrometers have been developed to measure the concentration, velocity, and temperature of ozone in the mesosphere and lower thermosphere (MLT) using low-cost satellite television electronics to observe the 11.072 GHz…

Instrumentation and Methods for Astrophysics · Physics 2015-08-18 O. B. Alam , A. E. E. Rogers

Information about the physical properties of astrophysical objects cannot be measured directly but is inferred by interpreting spectroscopic observations in the context of atomic physics calculations. Ratios of emission lines, for example,…

Knowing the behavior of solar radiation at a geographic location is essential for the use of energy from the sun using photovoltaic systems; however, the number of stations for measuring meteorological parameters and for determining the…

Machine Learning · Computer Science 2022-04-13 Luis Eduardo Ordoñez Palacios , Víctor Bucheli Guerrero , Hugo Ordoñez

Accurate estimates of historical changes in sea surface temperatures (SSTs) and their uncertainties are important for documenting and understanding historical changes in climate. A source of uncertainty that has not previously been…

Applications · Statistics 2020-12-15 Chenguang Dai , Duo Chan , Peter Huybers , Natesh Pillai

Bayesian model averaging enables one to combine the disparate predictions of a number of models in a coherent fashion, leading to superior predictive performance. The improvement in performance arises from averaging models that make…

Applications · Statistics 2011-08-01 Qingzhao Yu , Steven N. MacEachern , Mario Peruggia

The determination of the solar oxygen abundance remains a central problem in astrophysics, as its accuracy is limited not only by models but also by systematics. While many of these factors have been thoroughly characterized, the effect of…

Solar and Stellar Astrophysics · Physics 2026-02-11 A. G. M. Pietrow , M. Baratella , I. V. Ilyin , M. Steffen , K. G. Strassmeier

Birmingham Solar Oscillations Network (BiSON) instruments use resonant scattering spectrometers to make unresolved Doppler velocity observations of the Sun. Unresolved measurements are not homogenous across the solar disc and so the…

Solar and Stellar Astrophysics · Physics 2015-05-13 A. M. Broomhall , W. J. Chaplin , Y. Elsworth , R. New

The energy balance for an atmospheric layer near the soil is evaluated. By integrating it over the whole day period a linear relationship between the global daily solar radiation incident on a horizontal surface and the product of the…

Atmospheric and Oceanic Physics · Physics 2014-01-31 Antonio Dumas , Andrea Andrisani , Maurizio Bonnici , Mauro Madonia , Michele Trancossi

Context: The study of variations in total solar irradiance (TSI) is important for understanding how the Sun affects the Earth's climate. Aims: Full-disk continuum images and magnetograms are now available for three full solar cycles. We…

Solar and Stellar Astrophysics · Physics 2015-06-04 W. T. Ball , Y. C. Unruh , N. A. Krivova , S. Solanki , T. Wenzler , D. J. Mortlock , A. H. Jaffe

We use a new Atmospheric Chemistry and Energetics one-dimensional (ACE1D) thermospheric model to show that the energies deposited by the solar soft x-rays in the lower thermosphere at altitudes between 100 -150 km (Bailey et al. 2000),…

Earth and Planetary Astrophysics · Physics 2022-09-23 Srimoyee Samaddar , Karthik Venkataramani , Scott. M. Bailey

We examine SDO/EVE data to better understand solar flare irradiance, and how that irradiance may vary for large events. We measure scaling laws relating GOES flare classes to irradiance in 21 lines measured with SDO/EVE, formed across a…

Solar and Stellar Astrophysics · Physics 2022-03-14 Jeffrey W. Reep , David E. Siskind , Harry P. Warren

We establish a quantitative relationship between photometric and spectroscopic detections of solar-like oscillations using ab initio, three-dimensional (3D), hydrodynamical numerical simulations of stellar atmospheres. We present a…

Solar and Stellar Astrophysics · Physics 2021-02-17 Yixiao Zhou , Thomas Nordlander , Luca Casagrande , Meridith Joyce , Yaguang Li , Anish M. Amarsi , Henrique Reggiani , Martin Asplund

Understanding coronal structure and dynamics can be facilitated by analyzing green-line emission, which enables the investigation of diverse coronal structures such as coronal loops, streamers, coronal holes, and various eruptions in the…

Solar and Stellar Astrophysics · Physics 2024-11-27 Jacob Oloketuyi , Yu Liu , Linhua Deng , Abouazza Elmhamdi , Fengrong Zhu , Ayodeji Ibitoye , Opeyemi Omole , Feiyang Sha , Qiang Liu

Due to non-homogeneous mass distribution and non-uniform velocity rate inside the Sun, the solar outer shape is distorted in latitude. In this paper, we analyze the consequences of a temporal change in this figure on the luminosity. To do…

Solar and Stellar Astrophysics · Physics 2011-08-31 Z. Fazel , J. P. Rozelot , S. Lefebvre , A. Ajabshirizadeh , S. Pireaux

The inter-relation of clouds, solar irradiance and surface temperature is complex and subject to different interpretations. Here, we continue our recent work, which related mainly to the period from 1960 to the present, back to 1900 with…

Geophysics · Physics 2010-03-16 A. D. Erlykin , T. Sloan , A. W. Wolfendale

The Birmingham Solar-Oscillations Network (BiSON) has collected helioseismic data over three solar cycles. We use these data to determine how the internal properties of the Sun during this minimum differ from the previous two minima. The…

Solar and Stellar Astrophysics · Physics 2010-03-24 Sarbani Basu , Anne-Marie Broomhall , William J. Chaplin , Yvonne Elsworth , Stephen Fletcher , Roger New
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