What are solar faculae?

Kostyk, R. I.

doi:10.3103/s0884591313010030

Cited by 9 publications

(11 citation statements)

References 19 publications

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“…This latter dependence makes it possible to test theoretical models by means of observations. Indeed, observations of the solar disc center given in Frazier (1971), Title et al (1992), Topka et al (1992Topka et al ( , 1997, Montagne et al (1996), Kobel et al (2011), Kostyk (2013) show that the absolute value of continuum contrast of facular regions (without considering separately granules and intergranular lanes) depends on the magnetic field, though the observational findings are somewhat contradictory. Frazier (1971) shows that the continuum contrast of the facula at the solar disc center and the magnetogram signal are correlated in a complicated manner.…”

Section: Introductionmentioning

confidence: 98%

“…The line core images in Ba ii (middle panel) show suspicious brightness in the same locations as in the Ca ii H filtergram that correspond to the facular area under study. The data treatment is described in detail in Kostik & Khomenko (2012, 2013). In the current work, we study temporal variations in an area whose size is 5 .…”

Section: Observations and Data Reductionmentioning

confidence: 99%

“…Following our previous papers in this series (Kostik & Khomenko 2012;2013), we used observations performed at the German Vacuum Tower Telescope (VTT), located at the Observatorio del Teide in Izaña, Tenerife. The dataset was taken on 13 November 2007.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

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The possible origin of facular brightness in the solar atmosphere

Костик

Khomenko

2016

A&A

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This paper studies the dependence of the Ca ii H line core brightness on the strength and inclination of the photospheric magnetic field, and on the parameters of convective and wave motions in a facular region at the center of the solar disc. We use three simultaneous data sets that were obtained at the German Vacuum Tower Telescope (Observatorio del Teide, Tenerife): (1) spectra of Ba ii 4554 Å line, registered with the instrument TESOS to measure the variations of intensity and velocity through the photosphere up to the temperature minimum; (2) spectropolarimetric data in Fe i 1.56 µm lines (registered with the instrument TIP II) to measure photospheric magnetic fields; (3) filtergrams in Ca ii H that give information about brightness fluctuations in the chromosphere. The results show that the Ca ii H brightness in the facula strongly depends on the power of waves with periods in the 5-min range, which propagate upwards, and also on the phase shift between velocity oscillations at the bottom photosphere and around the temperature minimum height that is measured from Ba ii line. The Ca ii H brightness is maximum at locations where the phase shift between temperature and velocity oscillations lies within 0 • -100 • . There is an indirect influence of convective motions on the Ca ii H brightness. The higher the amplitude of convective velocities is and the greater the height is where they change their direction of motion, the brighter the facula. In summary, our results lead to conclusions that facular regions appear bright not only because of the Wilson depression in magnetic structures, but also owing to real heating.

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Section: Introductionmentioning

confidence: 98%

Section: Observations and Data Reductionmentioning

confidence: 99%

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The possible origin of facular brightness in the solar atmosphere

Костик

Khomenko

2016

A&A

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“…In this work, the authors use current achievements in the domain of diagnosis of magnetic fields in the solar chromosphere [3,18,19,21] and recent solutions for low threshold KAW generated in inhomoge neous plasma of the surface layer of a loop due to the development of a combined drift temperature insta bility [4]. The FAL PM [13] model of the solar atmosphere was used along with the MAVN F1 model [20]; the former considers the effect of helium diffusion process at chromospheric altitudes.…”

Section: Introductionmentioning

confidence: 99%

One type of three-wave interaction of low-frequency waves in magnetoactive plasma of the solar atmosphere

Kryshtal

Gerasimenko

Voitsekhovska

et al. 2014

Kinemat. Phys. Celest. Bodies

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We study the process of occurrence of "quasi mode" decay instability of kinetic Alfven waves (KAW) in the chromosphere of a solar active region before a flare, namely, in plasma of magnetic loops near their footpoints. The decay of a primary KAW into a kinetic ion acoustic wave and a sec ondary KAW was considered as a specific type of three wave interaction. Necessary conditions for the KAW decay instability occurrence were found for two semiempirical models of the solar atmosphere with the use of a modified expression for the growth rate of instability in the case of nonlinear interac tion of low frequency waves with an abnormally low excitation threshold. It was shown that the main criteria for the development of this instability significantly depend on the amplitude of external mag netic field in the region under study as well as on a model of the solar atmosphere.

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“…Já as fáculas, a olho nu, são mais difícies de serem discernidas das demais regiões do Sol, pois apresentam um contraste baixo demais para produzir contribuições visivelmente significativas para a intensidade local, sendo esse constrante perceptível somente com o uso de instrumentos. Assim, mesmo com a escuridão provocada pelas manchas solares, prevalece a luminosidade das fáculas e, no cômputo geral, o brilho solar aumenta (Kopp & Lean 2011, Kostyk 2013 Oliveira et al (2015) descrevem como os diversos tipos de testemunhos (anéis de arvores, sedimentos marinhos, núcleos de gelo, isótopos etc.) permitem reconstruir o clima no passado e seus diferentes componentes e fatores (precipitação, umidade, temperatura atmosférica, temperatura dos oceanos, nível dos oceanos, direção e velocidade dos ventos, variabilidade solar, atividades vulcânicas, circulação atmosférica, concentração de gases na atmosfera, produtividade biológica e nutrientes nos oceanos, distribuição de plantas e animais, vazão de rios, salinidade, pH, volume de gelo, extensão da calota polar, detritos transportados pelo gelo, entre outros).…”

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Ciclos climáticos e causas naturais das mudanças do clima

et al. 2018

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TerraeDid atic a IntroduçãoA presente histeria sobre aquecimento global -com a previsão apocalíptica de fusão das calotas de gelo polar, inundação de cidades costeiras e desertificação de zonas produtoras de alimentos -não ajuda os cidadãos a compreender as forças reais e complexas que moldam o clima da Terra (Hecht 1993(Hecht -1994.Tentar entender o clima tem sido prática de sobrevivência desde os primórdios da humanidade. Inegavelmente, compreender o momento ideal do plantio e da colheita fez parte das técnicas da agricultura primitiva que permitiram ao homem a transição do nomadismo para o sedentarismo. Assim, a partir da constatação da óbvia alternância entre o dia e a noite, da observação das fases da Lua, da dedução das estações do ano, foi-se descobrindo a estreita relação entre esses fenômenos (cíclicos e de origem astronômica) com as alterações do clima na Terra (também de caráter periódico). ABSTRACT:The periodic nature of climate changes on the Earth can be explained in terms of a limited number of terrestrial and astronomical factors. In annual/daily scales, the climate varies according to the Earth's revolution and rotation. Medium term climate cycles (decades/centuries/millennia) are related to changes in solar radiation caused by the influences of major planets of the Solar System. Oceanic oscillations (decadal order) are possibly caused by the planetary and lunar influences. Long term climate cycles (tens and hundreds of thousand years) are caused by variations in the parameters of Earth's orbit (eccentricity, obliquity and precession). Impact events of large bodies on the planet and mass extinction arise from supercycles (tens of millions of years) caused by the vertical oscillation of the solar system relative to the galactic plane. Tectonics, volcanism and the evolution of supercontinents exhibit supercycles (hundreds of million years) induced by the Solar System movement around the Milky Way center and by the cosmic rays variation. Astronomical factors permeate virtually all the climate cycles orders, acting directly or indirectly in many bio-geo-oceanic-atmospheric processes. It is concluded that the Earth's climate is characterized by cycles astronomically controlled by the Moon, the Sun, the planets, the Solar System and even the Galaxy. Ciclos climáticos e causas naturais das mudanças do clima

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What are solar faculae?

Cited by 9 publications

References 19 publications

The possible origin of facular brightness in the solar atmosphere

The possible origin of facular brightness in the solar atmosphere

One type of three-wave interaction of low-frequency waves in magnetoactive plasma of the solar atmosphere

Ciclos climáticos e causas naturais das mudanças do clima

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