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The relation between the intensity of chromospheric emissions and the photospheric magnetic field strength has been examined in several studies, but the effect of the magnetic field inclination on chromospheric emissions remains almost…

Solar and Stellar Astrophysics · Physics 2024-09-27 Ismo Tähtinen , Alexei A. Pevtsov , Timo Asikainen , Kalevi Mursula

Images of the Sun at millimeter wavelengths obtained by ALMA show a significant correspondence with the magnetograms. In this paper, we investigate this correspondence by comparing ALMA full-disk solar image taken at 1.2 mm with a SDO/HMI…

Solar and Stellar Astrophysics · Physics 2022-03-23 I. Skokić , D. Sudar , R. Brajša

Imaging observations of the solar lower atmosphere by the Atmosphere Imaging Assembly (AIA) have been mostly used as the context, and their quantitative information has been much less explored. The chromosphere responds rapidly to energy…

Solar and Stellar Astrophysics · Physics 2025-05-21 Jiong Qiu , Rhiannon Fleming

Solar mid-IR observations in the 8-15 micrometer band continuum with moderate angular resolution (18 arcseconds) reveal the presence of bright structures surrounding sunspots. These plage-like features present good association with calcium…

Astrophysics · Physics 2008-04-18 R. Marcon , P. Kaufmann , A. M. Melo , A. S. Kudaka , E. Tandberg-Hanssen

We investigate the relationship between the photospheric magnetic field of small-scale magnetic elements in the quiet Sun (QS) at disc centre, and the brightness at 214 nm, 300 nm, 313 nm, 388 nm, 397 nm, and at 525.02 nm. To this end we…

Solar and Stellar Astrophysics · Physics 2017-04-05 F. Kahil , T. L. Riethmüller , S. K. Solanki

Aims. We analyze observational data from 4 instruments to study the correlations between chromospheric emission, spanning the heights from the temperature minimum region to the middle chromosphere, and photospheric magnetic field. Methods:…

Solar and Stellar Astrophysics · Physics 2014-11-20 Maria A. Loukitcheva , Sami K. Solanki , Stephen M. White

Plage regions are patches of concentrated magnetic field in the Sun's atmosphere where hot coronal loops are rooted. While previous studies have shed light on the properties of plage magnetic fields in the photosphere, there are still…

Solar and Stellar Astrophysics · Physics 2023-08-23 J. M. da Silva Santos , K. Reardon , G. Cauzzi , T. Schad , V. Martinez Pillet , A. Tritschler , F. Wöger , R. Hofmann , J. Stauffer , H. Uitenbroek

The Sun is replete with magnetic fields, with sunspots, pores and plage regions being their most prominent representatives on the solar surface. But even far away from these active regions, magnetic fields are ubiquitous. To a large extent,…

Solar and Stellar Astrophysics · Physics 2015-11-05 Andreas Lagg , Bruce Lites , Jack Harvey , Sanjay Gosain , Rebecca Centeno

Context. Stellar spectral variability on timescales of a day and longer, arising from magnetic surface features such as dark spots and bright faculae, is an important noise source when characterising extra-solar planets. Current 1D models…

Solar and Stellar Astrophysics · Physics 2017-09-06 Charlotte M. Norris , Benjamin Beeck , Yvonne C. Unruh , Sami K. Solanki , Natalie A. Krivova , Kok Leng Yeo

Sunspots, faculae and the magnetic network contribute to solar irradiance variations. The contribution due to faculae and the network is of basic importance, but suffers from considerable uncertainty. We determine the contrasts of active…

Astrophysics · Physics 2009-11-07 A. Ortiz , S. K. Solanki , V. Domingo , M. Fligge , B. Sanahuja

The problem of solar chromospheric heating remains a challenging one with wider implications for stellar physics. Several studies in the recent past have shown that small-scale inclined magnetic field elements channel copious amount of…

Solar and Stellar Astrophysics · Physics 2018-12-14 S. P. Rajaguru , C. R. Sangeetha , Durgesh Tripathi

The irradiance of the Sun is modulated on all time scales. Small-scale solar magnetic elements composed of quiet-Sun network and active region plages contribute to this modulation on solar cycle time scales. The evaluation of their contrast…

Solar and Stellar Astrophysics · Physics 2021-09-02 Fatima Kahil

The chromosphere is a complex solar atmosphere that hosts a variety of transients and transports significant free energy to heat the corona. However, due to the limited sensitivity of polarization measurement and the influence of spectral…

Solar and Stellar Astrophysics · Physics 2026-03-24 Jiasheng Wang , Wenxian Li , Xianyong Bai , Yingzi Sun , Yuanyong Deng , Jiaben Lin

Sunspots are dark spots on the solar surface associated with strong magnetic fields. The number, area, and brightness of sunspots are supposed to reflect the intensity of the solar magnetic fields and are often used as proxies for their…

Solar and Stellar Astrophysics · Physics 2015-06-16 K. Georgieva , B. Kirov , Yu. A. Nagovitsyn

The \textit{Sun Watcher using Active Pixel system detector and Image Processing}(SWAP) on board the \textit{PRoject for OnBoard Autonomy\todash 2} (PROBA\todash 2) spacecraft provides images of the solar corona in EUV channel centered at…

Solar and Stellar Astrophysics · Physics 2012-06-11 K. Chandrashekhar , S. Krishna Prasad , D. Banerjee , B. Ravindra , Daniel B. Seaton

The evolution of the photospheric magnetic field plays a key role in the energy transport into the chromosphere and the corona. In active regions, newly emerging magnetic flux interacts with the pre-existent magnetic field, which can lead…

Solar and Stellar Astrophysics · Physics 2021-04-07 C. J. Díaz Baso , J. de la Cruz Rodríguez , J. Leenaarts

Magnetic features on the surface of stars, such as spots and faculae, cause stellar spectral variability on time-scales of days and longer. For stars other than the Sun, the spectral signatures of faculae are poorly understood, limiting our…

Solar observations with the Atacama Large Millimeter/submillimeter Array (ALMA) provide us with direct measurements of the brightness temperature in the solar chromosphere. We study the temperature distributions obtained with ALMA Band 6…

Solar and Stellar Astrophysics · Physics 2019-02-13 Shahin Jafarzadeh , Sven Wedemeyer , Mikolaj Szydlarski , Bart De Pontieu , Reza Rezaei , Mats Carlsson

Magnetic elements have an intensity contrast that depends on the type of region they are located in (e.g. quiet Sun, or active region plage). Observed values also depend on the spatial resolution of the data. Here we investigate the…

Solar and Stellar Astrophysics · Physics 2019-01-16 F. Kahil , T. L. Riethmüller , S. K. Solanki

Small-scale magnetic fields are major contributors to the solar irradiance variations. Hence, the continuum intensity contrast of magnetic elements in the quiet Sun (QS) network and in active region (AR) plage is an essential quantity that…

Solar and Stellar Astrophysics · Physics 2015-05-28 P. Kobel , S. K. Solanki , J. M. Borrero
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