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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…

太阳与恒星天体物理 · 物理学 2023-02-01 I. Skokić , A. O. Benz , R. Brajša , D. Sudar , F. Matković , M. Bárta

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…

太阳与恒星天体物理 · 物理学 2020-12-23 Henrik Eklund , Sven Wedemeyer , Mikolaj Szydlarski , Shahin Jafarzadeh , Juan Camilo Guevara Gómez

A spectacular manifestation of solar activity is the appearance of transient brightenings in the far wings of the H$\alpha$ line, known as Ellerman bombs (EBs). Recent observations obtained by the Interface Region Imaging Spectrograph…

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…

太阳与恒星天体物理 · 物理学 2021-08-18 A. Nindos , S. Patsourakos , C. E. Alissandrakis , T. S. Bastian

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…

太阳与恒星天体物理 · 物理学 2020-07-01 A. Nindos , C. E. Alissandrakis , S. Patsourakos , T. S. Bastian

The solar chromosphere is heated to temperatures higher than predicted by radiative equilibrium. This excess heating is greater in active regions where the magnetic field is stronger. We aim to investigate the magnetic topology associated…

太阳与恒星天体物理 · 物理学 2022-05-04 J. M. da Silva Santos , S. Danilovic , J. Leenaarts , J. de la Cruz Rodríguez , X. Zhu , S. M. White , G. J. M. Vissers , M. Rempel

The Ca II H & K lines are strong chromospheric diagnostics that can be used to determine the temperature stratification and magnetic structure of the solar atmosphere. The Atacama Large Millimetre/Submillimetre Array (ALMA) offers…

太阳与恒星天体物理 · 物理学 2024-05-09 Sneha Pandit , Sven Wedemeyer , Mats Carlsson

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…

太阳与恒星天体物理 · 物理学 2015-02-18 Sven Wedemeyer , Asbjorn Parmer

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…

We report the discovery of a brightness enhancement in the center of a large sunspot umbra at a wavelength of 3 mm using the Atacama Large Millimeter/sub-millimeter Array (ALMA). Sunspots are amongst the most prominent features on the solar…

太阳与恒星天体物理 · 物理学 2017-05-31 Kazumasa Iwai , Maria Loukitcheva , Masumi Shimojo , Sami K. Solanki , Stephen M. White

We investigate the thermal, kinematic and magnetic structure of small-scale heating events in an emerging flux region (EFR). We use high-resolution multi-line observations (including Ca II 8542~\AA, Ca II K, and Fe I 6301~\AA line pair) of…

太阳与恒星天体物理 · 物理学 2023-09-14 Rahul Yadav , Maria D. Kazachenko , Andrey N. Afanasyev , Jaime de la Cruz Rodríguez , Jorrit Leenaarts

The aim of this study is to demonstrate how the logarithmic millimeter continuum gradient observed using the Atacama Large Millimeter/submillimeter Array (ALMA) may be used to estimate optical thickness in the solar atmosphere. We discuss…

太阳与恒星天体物理 · 物理学 2019-05-01 Andrew S. Rodger , Nicolas Labrosse , Sven Wedemeyer , Mikolaj Szydlarski , Paulo J. A. Simões , Lyndsay Fletcher

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…

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…

太阳与恒星天体物理 · 物理学 2019-02-13 Shahin Jafarzadeh , Sven Wedemeyer , Mikolaj Szydlarski , Bart De Pontieu , Reza Rezaei , Mats Carlsson

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…

太阳与恒星天体物理 · 物理学 2021-07-07 R. Brajsa , I. Skokic , D. Sudar , A. O. Benz , S. Krucker , H. -G. Ludwig , S. H. Saar , C. L. Selhorst

We study small-scale brightenings in Ca II 8542 \AA\ line-core images to determine their nature and effect on localized heating and mass transfer in active regions. High-resolution 2D spectroscopic observations of an active region in the Ca…

The intensity of radiation at millimeter wavelengths from the solar atmosphere is closely related to the plasma temperature and the height of formation of the radiation is wavelength dependent. From that follows that the slope of the…

太阳与恒星天体物理 · 物理学 2023-01-18 Henrik Eklund , Mikolaj Szydlarski , Sven Wedemeyer

The continuum intensity at wavelengths around 1 mm provides an excellent way to probe the solar chromosphere. Future high-resolution millimetre arrays, such as the Atacama Large Millimeter Array (ALMA), will thus produce valuable input for…

天体物理学 · 物理学 2009-11-13 S. Wedemeyer-Boehm , H. -G. Ludwig , M. Steffen , J. Leenaarts , B. Freytag

Microflares have been considered to be among the major energy input sources to form active solar corona. To investigate the response of the low atmosphere to events, we conducted an ALMA observation at 3 mm coordinated with IRIS and Hinode…

太阳与恒星天体物理 · 物理学 2021-12-08 Toshifumi Shimizu , Masumi Shimojo , Masashi Abe

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…

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