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The incoherence of sunlight has long been suspected to have an impact on solar cell energy conversion efficiency, although the extent of this is unclear. Existing computational methods used to optimize solar cell efficiency under incoherent…

Optics · Physics 2014-01-16 Aline Herman , Michael Sarrazin , Olivier Deparis

Stellar coronagraphs designed for high-contrast imaging of exoplanets inevitably introduce a small amount of instrumental polarization, called \emph{secondary polarization}. At the contrast levels required to detect and characterize…

Instrumentation and Methods for Astrophysics · Physics 2025-08-04 Richard A. Frazin

The Sky Brightness Monitor (SBM) is an important instrument to measure the brightness level for the sky condition, which is a critical parameter for judging a site for solar coronal observations. In this paper we present an automatic method…

Solar and Stellar Astrophysics · Physics 2015-06-22 M. Y. Zhao , Y. Liu , A. Elmhamdi , A. S. Kordi , H. A. Al-trabulsy , X. F. Zhang , T. F. Song , S. Q. Liu , Y. D. Shen , Z. J. Tian , Y. H. Miao

The probability distribution of temperature of a blackbody can be determined from its power spectrum. This technique is called blackbody radiation inversion. In the present paper blackbody radiation inversion is applied on the spectrum of…

Solar and Stellar Astrophysics · Physics 2021-04-09 Koustav Konar , Kingshuk Bose , R. K. Paul

The unprecedented precision of broadband stellar photometry achieved with the planet-hunting missions CoRoT and \textit{Kepler} initiated a new era in examining the magnetically-driven brightness variations of hundreds of thousands of…

Solar and Stellar Astrophysics · Physics 2021-06-25 Nina-Elisabet Nèmec

From photoelectric observations of night sky brightness carried out at Abu-Simbel, Asaad et al. (1979) have obtained values of integrated starlight brightness at different Galactic latitudes. These data have been used in the present work to…

Astrophysics of Galaxies · Physics 2011-07-28 S. Nawar , A. L. Tadross , J. S. Mikhail , A. B. Morcos

Determination of the coronal electron density by the inversion of white-light polarized brightness (pB) measurements by coronagraphs is a classic problem in solar physics. An inversion technique based on the spherically symmetric geometry…

Solar and Stellar Astrophysics · Physics 2014-06-30 Tongjiang Wang , Joseph M. Davila

Regular spaceborne measurements have revealed that solar brightness varies on multiple timescales, variations on timescales greater than a day being attributed to surface magnetic field. Independently, ground-based and spaceborne…

Solar and Stellar Astrophysics · Physics 2016-04-27 A. I. Shapiro , S. K. Solanki , N. A. Krivova , K. L. Yeo , W. K. Schmutz

The large availability and rich spectral coverage of today's observational data of the solar corona, and the high spatial and temporal resolution of many instruments, has enabled the evolution of three-dimensional (3D) physical models to a…

Solar and Stellar Astrophysics · Physics 2015-03-10 Alberto Marcos Vásquez

EUV images of Comet Lovejoy (C/2011 W3) from the AIA show striations related to the magnetic field structure in both open and closed magnetic regions. The brightness contrast implies coronal density contrasts of at least a factor of 6…

Solar and Stellar Astrophysics · Physics 2015-06-19 J. C. Raymond , P. I. McCauley , S. R. Cranmer , C. Downs

Direct imaging of exoplanets requires very high contrast levels, which are obtained using coronagraphs. But residual quasi-static aberrations create speckles in the focal plane downstream of the coronagraph which mask the planet. This…

Instrumentation and Methods for Astrophysics · Physics 2015-06-16 J. Mazoyer , P. Baudoz , R. Galicher , M. Mas , G. Rousset

We derive contrast measures which involve the number of looks and the complex correlation coefficient between polarization channels in PolSAR imagery. Using asymptotic results which characterize the behavior of these measures, we derive…

Statistics Theory · Mathematics 2014-02-11 Alejandro C. Frery , Renato J. Cintra , Abraão D. C. Nascimento

Total eclipses permit a deep analysis of both the inner and the outer parts of the corona using the continuum White-Light (W-L) radiations from electrons (K-corona), the superposed spectrum of forbidden emission lines from ions (E-corona)…

Solar and Stellar Astrophysics · Physics 2019-12-11 S. Koutchmy , F. Baudin , Sh. Abdi , L. Golub , F. Sèvre

Since the Lalpha rocket observations of (Gabriel, Solar Phys. 21, 392, 1971), it has been realized that the hydrogen (H) lines could be observed in the corona and offer an interesting diagnostic for the temperature, density, and radial…

Solar and Stellar Astrophysics · Physics 2016-11-15 Jean-Claude Vial , Martine Chane-Yook

Understanding the global rotational profile of the solar atmosphere and its variation is fundamental to uncovering a comprehensive understanding of the dynamics of the solar magnetic field and the extent of coupling between different layers…

We have examined images from the Precision Solar Photometric Telescope (PSPT) at the Mauna Loa Solar Observatory (MLSO) in search of latitudinal variation in the solar photospheric intensity. Along with the expected brightening of the solar…

Astrophysics · Physics 2009-11-13 Mark P. Rast , Ada Ortiz , Randle W. Meisner

Solar wind models predict that the mass flux carried away from the Sun in the solar wind should be extremely sensitive to the temperature in the corona, where the solar wind is accelerated. We perform a direct test of this prediction in…

Solar and Stellar Astrophysics · Physics 2021-06-02 D. Stansby , L. Berčič , L. Matteini , C. J. Owen , R. French , D. Baker , S. T. Badman

We have reanalyzed SUMER observations of a parcel of coronal gas using new collisional ionization equilibrium (CIE) calculations. These improved CIE fractional abundances were calculated using state-of-the-art electron-ion recombination…

Astrophysics · Physics 2011-02-11 P. Bryans , E. Landi , D. W. Savin

The solar corona and heliosphere are visible via sunlight that is Thomson-scattered off of free electrons, yielding a radiance against the celestial sphere. In this second part of a three-article series, we discuss linear polarization of…

Instrumentation and Methods for Astrophysics · Physics 2015-06-05 C. E. DeForest , T. A. Howard , S. J. Tappin

Coronal magnetic fields are well known to be one of the crucial parameters defining coronal physics and space weather. However, measuring the global coronal magnetic fields remains challenging. The polarization properties of coronal radio…

Solar and Stellar Astrophysics · Physics 2022-07-01 Devojyoti Kansabanik , Divya Oberoi , Surajit Mondal