ALMA Observations of the Sun in Cycle 4 and Beyond

Wedemeyer, Sven; Fleck, B.; Battaglia, Marina; Labrosse, Nicolas; Fleishman, G. D.; Hudson, H.; Antolin, Patrick; Alissandrakis, C. E.; Ayres, T.; Ballester, J. L.; Bastian, T.; Black, J. H.; Benz, A. O.; Brajša, R.; Carlsson, M.; Costa, J. E. R.; DePontieu, Bart; Doyle, G.; Castro, G. Giménez de; Gunár, S.; Harper, Graham M.; Jafarzadeh, S.; Loukitcheva, M.; Nakariakov, V. M.; Oliver, R.; Schmieder, B.; Selhorst, C. L.; Shimojo, Masataka; Simões, Paulo J. A.; Soler, Roberto; Temmer, Manuela; Tiwari, Sanjiv K.; Doorsselaere, Tom Van; Veronig, A.; White, S. M.; Yagoubov, P.; Zaqarashvili, T. V.

doi:10.48550/arxiv.1601.00587

Cited by 2 publications

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“…The departures from the Rayleigh-Jeans law seen in Figure 5 suggest that future flare observations with the Atacama Large Millimeter/sub-millimeter Array (ALMA, Wedemeyer et al 2016) will help to find the temperature structure of the flaring chromosphere, providing valuable information to identify the energy transport mechanisms. Note, however, that at mm-waves the contribution from synchrotron emission from non-thermal electrons may become important or even dominant (e.g.…”

Section: Discussionmentioning

confidence: 99%

Formation of the thermal infrared continuum in solar flares

Simões

Kerr

Fletcher

et al. 2017

A&A

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Aims. Observations of the Sun with the Atacama Large Millimeter Array have now started, and the thermal infrared will regularly be accessible from the NSF's Daniel K. Inouye Solar Telescope. Motivated by the prospect of these new data, and by recent flare observations in the mid infrared, we set out here to model and understand the source of the infrared continuum in flares, and to explore its diagnostic capability for the physical conditions in the flare atmosphere. Methods. We use the one-dimensional (1D) radiation hydrodynamics code RADYN to calculate mid-infrared continuum emission from model atmospheres undergoing sudden deposition of energy by non-thermal electrons. Results. We identify and characterise the main continuum thermal emission processes relevant to flare intensity enhancement in the mid-to far-infrared (2-200 µm) spectral range as free-free emission on neutrals and ions. We find that the infrared intensity evolution tracks the energy input to within a second, albeit with a lingering intensity enhancement, and provides a very direct indication of the evolution of the atmospheric ionisation. The prediction of highly impulsive emission means that, on these timescales, the atmospheric hydrodynamics need not be considered in analysing the mid-IR signatures.

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Section: Discussionmentioning

confidence: 99%

Formation of the thermal infrared continuum in solar flares

Simões

Kerr

Fletcher

et al. 2017

A&A

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“…The Hinode and IRIS observations presented here, at a level of clarity not previously achieved, have offered new insights to rotational motions of fine-structure prominence threads. Additional observations in even greater detail, including temperature measurements, will soon be provided by the Atacama Large Millimeter/submillimeter Array (ALMA) in its observing Cycle 4 starting 2016 (see Wedemeyer et al 2016). We anticipate to utilize the combination of such unprecedented observations to further probe the physics of prominence activations and related phenomena.…”

Section: Discussion On Helical Motions Of Prominence Threadsmentioning

confidence: 99%

Helical Motions of Fine-Structure Prominence Threads Observed by Hinode and Iris

Okamoto

Liu

Tsuneta

2016

ApJ

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Fine-structure dynamics in solar prominences holds critical clues to understanding their physical nature of significant space-weather implications. We report evidence of rotational motions of horizontal helical threads in two activeregion prominences observed by the Hinode and/or IRIS satellites at high resolution. In the first event, we found transverse motions of brightening threads at speeds up to 55 km s −1 seen in the plane of the sky. Such motions appeared as sinusoidal space-time trajectories with a typical period of ∼390 s, which is consistent with plane-of-sky projections of rotational motions. Phase delays at different locations suggest propagation of twists along the threads at phase speeds of 90-270 km s −1 . At least 15 episodes of such motions occurred in two days, none associated with any eruption. For these episodes, the plane-of-sky speed is linearly correlated with the vertical travel distance, suggestive of a constant angular speed. In the second event, we found Doppler velocities of 30-40 km s −1 in opposite directions in the top and bottom portions of the prominence, comparable to the plane-of-sky speed. The moving threads have about twice broader line widths than stationary threads. These observations, when taken together, provide strong evidence for rotations of helical prominence threads, which were likely driven by unwinding twists triggered by magnetic reconnection between twisted prominence magnetic fields and ambient coronal fields.

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ALMA Observations of the Sun in Cycle 4 and Beyond

Cited by 2 publications

References 0 publications

Formation of the thermal infrared continuum in solar flares

Formation of the thermal infrared continuum in solar flares

Helical Motions of Fine-Structure Prominence Threads Observed by Hinode and Iris

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