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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

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 radio emissions offer unique diagnostic insights into the solar corona. However, their dynamic and multiscale nature, along with several orders of magnitude variations in intensity, pose significant observational challenges. To date,…

The precise mechanisms that provide the non-radiative energy for heating the chromosphere and the corona of the Sun and other stars are at the focus of intense contemporary research. Observations at submm/mm wavelengths are particularly…

Solar and Stellar Astrophysics · Physics 2016-10-19 R. Liseau , V. De la Luz , E. O'Gorman , E. Bertone , M. Chavez , F. Tapia

In this work we use solar observations with the ALMA radio telescope at the wavelength of 1.21 mm. The aim of the analysis is to improve understanding of the solar chromosphere, a dynamic layer in the solar atmosphere between the…

Solar and Stellar Astrophysics · Physics 2018-12-19 R. Brajša , D. Sudar , I. Skokic , A. O. Benz , M. Kuhar , A. Kobelski , S. Wedemeyer , S. M. White , H. -G. Ludwig , M. Temmer , S. H. Saar , C. L. Selhorst

At radio wavelengths, solar-type stars emit thermal free-free and gyroresonance, gyrosynchrotron, and impulsive coherent emission. Thermal free-free emission originates at layers where the optical depth is close to unit, while high…

Solar and Stellar Astrophysics · Physics 2018-08-29 C. Trigilio , G. Umana , F. Cavallaro , C. Agliozzo , P. Leto , C. S. Buemi , A. Ingallinera , F. Bufano , S. Riggi

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

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 have developed an affordable, portable college level radio telescope for amateur radio astronomy which can be used to provide hands-on experience with the fundamentals of a radio telescope and an insight into the realm of radio…

Physics Education · Physics 2016-01-13 Pranshu Mandal , Devansh Agarwal , Pratik Kumar , Anjali Yelikar , Kanchan Soni , Vineeth Krishna T

We present joint observations of the Sun by the Atacama Large Millimeter/submillimeter Array (ALMA) and the Interface Region Imaging Spectrograph (IRIS). The observations were made of a solar active region on 2015 December 18 as part of the…

Solar and Stellar Astrophysics · Physics 2017-08-30 T. S. Bastian , G. Chintzoglou , B. De Pontieu , M. Shimojo , D. Schmit , J. Leenaarts , M. Loukitcheva

The (sub)millimeter radiation of solar flares is poorly understood. Without spatial resolution, it cannot be compared easily to flare emissions in other wavelengths. The Atacama Large Millimeter-submillimeter Array (ALMA) offers sufficient…

Solar and Stellar Astrophysics · Physics 2023-02-01 I. Skokić , A. O. Benz , R. Brajša , D. Sudar , F. Matković , M. Bárta

We present a new solar radio imaging system implemented through the upgrade of the large single-dish telescopes of the Italian National Institute for Astrophysics (INAF), not originally conceived for solar observations. During the…

The Atacama Large Millimeter/submillimeter Array (ALMA) offers new diagnostic possibilities that complement other commonly used diagnostics for the study of our Sun. In particular, ALMA's ability to serve as an essentially linear…

We present observational constraints on the solar chromospheric heating contribution from acoustic waves with frequencies between 5 and 50 mHz. We utilize observations from the Dunn Solar Telescope in New Mexico complemented with…

Solar and Stellar Astrophysics · Physics 2021-11-03 Momchil E. Molnar , Kevin P. Reardon , Steven R. Cranmer , Adam F. Kowalski , Yi Chai , Dale Gary

Sky models have been used in the past to calibrate individual low radio frequency telescopes. Here we generalize this approach from a single antenna to a two element interferometer and formulate the problem in a manner to allow us to…

Instrumentation and Methods for Astrophysics · Physics 2017-06-28 Divya Oberoi , Rohit Sharma , Alan E. E. Rogers

We used solar observations of a plage/enhanced network with the Atacama Large Millimeter/sub-millimeter Array (ALMA) in Band 3 and Band 6 together with synthetic continuum maps from numerical simulations with Bifrost at the same bands to…

We present spectropolarimetric imaging observations of the solar corona at low frequencies (80 - 240 MHz) using the Murchison Widefield Array (MWA). These images are the first of their kind, and we introduce an algorithm to mitigate an…

Solar and Stellar Astrophysics · Physics 2019-09-04 Patrick I. McCauley , Iver H. Cairns , Stephen M. White , Surajit Mondal , Emil Lenc , John Morgan , Divya Oberoi

The almost unexplored frequency window from submillimeter to mid-infrared (mid-IR) may bring new clues about the particle acceleration and transport processes and the atmospheric thermal response during solar flares. Because of its…

The Atacama Millimeter/Submillimeter Array (ALMA) remains unparalleled in sensitivity at radio frequencies above 35 GHz. In this paper, we explore ALMA's potential for narrowband technosignature detection, considering factors such as the…

Instrumentation and Methods for Astrophysics · Physics 2024-12-02 Louisa A Mason , Michael A Garrett , Kelvin Wandia , Andrew P V Siemion

The Atacama Large Millimeter Array (ALMA) has revolutionised the field of solar millimetre astronomy with its high angular resolution and cadence. However, with a limited field of view (FOV), targeted observations of highly dynamic…

Solar and Stellar Astrophysics · Physics 2025-09-10 Mats Kirkaune , Sven Wedemeyer , Joshiwa van Marrewijk , Tony Mroczkowski , Thomas W. Morris