Chromospheric counterparts of solar transition region unresolved fine structure loops

Low-lying loops have been discovered at the solar limb in transition region temperatures by the Interface Region Imaging Spectrograph (IRIS). They do not appear to reach coronal temperatures, and it has been suggested that they are the long-predicted unresolved fine structures (UFS). These loops are...

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Bibliographic Details
Published in:Astronomy and astrophysics (Berlin) 2018-03, Vol.611, p.L6
Main Authors: Pereira, Tiago M. D., van der Voort, Luc Rouppe, Hansteen, Viggo H., De Pontieu, Bart
Format: Article
Language:English
Subjects:
Chromosphere
Coronas
Fine structure
Heating
Solar limb
Solar transition region
Sun: chromosphere
Sun: transition region
Sun: UV radiation
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Summary:Low-lying loops have been discovered at the solar limb in transition region temperatures by the Interface Region Imaging Spectrograph (IRIS). They do not appear to reach coronal temperatures, and it has been suggested that they are the long-predicted unresolved fine structures (UFS). These loops are dynamic and believed to be visible during both heating and cooling phases. Making use of coordinated observations between IRIS and the Swedish 1-m Solar Telescope, we study how these loops impact the solar chromosphere. We show for the first time that there is indeed a chromospheric signal of these loops, seen mostly in the form of strong Doppler shifts and a conspicuous lack of chromospheric heating. In addition, we find that several instances have a inverse Y-shaped jet just above the loop, suggesting that magnetic reconnection is driving these events. Our observations add several puzzling details to the current knowledge of these newly discovered structures; this new information must be considered in theoretical models.
ISSN:0004-6361
1432-0746
DOI:10.1051/0004-6361/201832762