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Using Atacama Large Millimeter/submillimeter Array (ALMA) observations of the quiet Sun at 1.26 and 3 mm, we study spatially resolved oscillations and transient brightenings, i.e. small, weak events of energy release. Both phenomena may…

Solar and Stellar Astrophysics · Physics 2021-08-18 A. Nindos , S. Patsourakos , C. E. Alissandrakis , T. S. Bastian

By direct measurements of the gas temperature, the Atacama Large Millimeter/sub-millimeter Array (ALMA) has yielded a new diagnostic tool to study the solar chromosphere. Here we present an overview of the brightness-temperature…

We present an overview of high resolution quiet Sun observations, from disk center to the limb, obtained with the Atacama Large mm and sub-mm Array (ALMA) at 3 mm. Seven quiet Sun regions were observed with resolution of up to 2.5" by 4.5".…

We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of a quiet-Sun region at a wavelength of 3 mm, obtained during the first solar ALMA cycle on April 27, 2017, and compare them with available chromospheric…

Solar and Stellar Astrophysics · Physics 2019-06-05 Maria A. Loukitcheva , Stephen M. White , Sami K. Solanki

Using ALMA observations, we performed the first systematic survey for transient brightenings (i.e. weak, small-scale episodes of energy release) in the quiet solar chromosphere at 3 mm. Our dataset included images of six 87'' x 87'' regions…

Solar and Stellar Astrophysics · Physics 2020-07-01 A. Nindos , C. E. Alissandrakis , S. Patsourakos , T. S. Bastian

The very nature of the solar chromosphere, its structuring and dynamics, remains far from being properly understood, in spite of intensive research. Here we point out the potential of chromospheric observations at millimeter wavelengths to…

Astrophysics · Physics 2009-06-23 M. A. Loukitcheva , S. K. Solanki , S. White

Solar observations at sub-mm, mm and cm wavelengths offer a straightforward diagnostic of physical conditions in the solar atmosphere because they yield measurement of brightness temperature which, for optically thick features, equals…

Solar and Stellar Astrophysics · Physics 2022-09-07 Costas Alissandrakis , Timothy Bastian , Roman Brajša

We report detection of oscillations in brightness temperature, size, and horizontal velocity of three small bright features in the chromosphere of a plage/enhanced-network region. The observations, which were taken with high temporal…

Solar observations with the Atacama Large Millimeter/sub-millimeter Array (ALMA) facilitate studying the atmosphere of the Sun at chromospheric heights at high spatial and temporal resolution at millimeter wavelengths. ALMA intensity data…

Solar and Stellar Astrophysics · Physics 2020-12-23 Henrik Eklund , Sven Wedemeyer , Mikolaj Szydlarski , Shahin Jafarzadeh , Juan Camilo Guevara Gómez

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

Waves and oscillations are important solar phenomena, not only because they can propagate and dissipate energy in the chromosphere, but also because they carry information about the structure of the atmosphere in which they propagate. The…

Solar and Stellar Astrophysics · Physics 2022-01-26 Yi Chai , Dale E. Gary , Kevin P. Reardon , Vasyl Yurchyshyn

We present the first full-disk solar images obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) in Band 7 (0.86 mm; 347 GHz). In spite of the low spatial resolution (21"), several interesting results were obtained. During…

Solar and Stellar Astrophysics · Physics 2022-05-25 C. E. Alissandrakis , T. S. Bastian , A. Nindos

The Atacama Large Millimeter/sub-millimeter Array (ALMA) has provided us with an excellent diagnostic tool for studies of the dynamics of the Solar chromosphere, albeit through a single receiver band at one time presently. Each ALMA band…

Solar and Stellar Astrophysics · Physics 2022-09-14 Juan Camilo Guevara Gómez , Shahin Jafarzadeh , Sven Wedemeyer , Mikolaj Szydlarski

We present an initial study of one of the first ALMA Band 3 observations of the Sun with the aim to characterise the diagnostic potential of brightness temperatures measured with ALMA on the Sun. The observation covers 48min at a cadence of…

ALMA observations of the Sun at mm-$\lambda$ offer a unique opportunity to investigate the temperature structure of the solar chromosphere. In this article we expand our previous work on modeling the chromospheric temperature of the quiet…

Solar and Stellar Astrophysics · Physics 2020-08-19 C. E. Alissandrakis , A. Nindos , T. S. Bastian , S. Patsourakos

The Atacama Large Millimeter/submillimeter Array offers an unprecedented view of our Sun at sub-/millimeter wavelengths. The high spatial, temporal, and spectral resolution facilitates the measurement of gas temperatures and magnetic fields…

Solar and Stellar Astrophysics · Physics 2015-02-18 Sven Wedemeyer , Asbjorn Parmer

Aims. The main aim of the present analysis is to decipher (i) the small-scale bright features in solar images of the quiet Sun and active regions obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) and (ii) the ALMA…

Solar and Stellar Astrophysics · Physics 2021-07-07 R. Brajsa , I. Skokic , D. Sudar , A. O. Benz , S. Krucker , H. -G. Ludwig , S. H. Saar , C. L. Selhorst

The precise mechanisms that provide the non-radiative energy for heating the chromosphere and the corona of the Sun and those of other stars constitute an active field of research. By studying stellar chromospheres one aims at identifying…

Recent three-dimensional radiation hydrodynamic simulations by Wedemeyer et al. (2004) suggest that the solar chromosphere is highly structured in space and time on scales of only 1000 km and 20-25 sec, resp.. The resulting pattern consists…

Astrophysics · Physics 2007-05-23 S. Wedemeyer-Boehm , H. -G. Ludwig , M. Steffen , B. Freytag , H. Holweger

The Atacama Large Millimeter/submillimeter Array (ALMA) allows for solar observations in the wavelength range of 0.3$-$10 mm, giving us a new view of the chromosphere. The measured brightness temperature at various frequencies can be fitted…

Solar and Stellar Astrophysics · Physics 2024-03-01 F. Matković , R. Brajša , M. Kuhar , A. O. Benz , H. -G. Ludwig , C. L. Selhorst , I. Skokić , D. Sudar , A. Hanslmeier
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