The 6 September 2017 X9 super flare observed from submillimeter to mid-IR

Giménez de Castro, C.G., Raulin, J.-P., Valle Silva, J., Simões, P.J.A. , Kudaka, A.S. and Valio, A. (2018) The 6 September 2017 X9 super flare observed from submillimeter to mid-IR. Space Weather, 16(9), pp. 1261-1268. (doi: 10.1029/2018sw001969)

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Active Region 12673 is the most productive active region of solar cycle 24: in a few days of early September 2017, four X‐class and 27 M‐class flares occurred. SOL2017‐09‐06T12:00, an X9.3 flare also produced a two‐ribbon white light emission across the sunspot detected by Solar Dynamics Orbiter/Helioseismic and Magnetic Imager. The flare was observed at 212 and 405 GHz with the arcminute‐sized beams of the Solar Submillimeter Telescope focal array while making a solar map and at 10 μm, with a 17 arcsec diffraction‐limited infrared camera. Images at 10 μm revealed that the sunspot gradually increased in brightness while the event proceeded, reaching a temperature similar to quiet Sun values. From the images we derive a lower bound limit of 180‐K flare peak excess brightness temperature or 7,000 sfu if we consider a similar size as the white light source. The rising phase of mid‐IR and white light is similar, although the latter decays faster, and the maximum of the mid‐IR and white light emission is ∼200 s delayed from the 15.4‐GHz peak occurrence. The submillimeter spectrum has a different origin than that of microwaves from 1 to 15 GHz, although it is not possible to draw a definitive conclusion about its emitting mechanism.

Item Type:Articles
Additional Information:This research was financed by the Brazilian Agency FAPESP through grant 2013/24155-3, by the U.S. Air Force Office for Scientific Research FA9550-16-1-0072, and by the MackPesquisa grant. P. J. A. S. acknowledges support from the University of Glasgow’s Lord Kelvin Adam Smith Leadership Fellowship. C. G. G. C. and J. P. R. are thankful to CNPq by the support through grants 305203/2016-9 and 312066/2016-3, respectively.
Glasgow Author(s) Enlighten ID:Simoes, Dr Paulo
Authors: Giménez de Castro, C.G., Raulin, J.-P., Valle Silva, J., Simões, P.J.A., Kudaka, A.S., and Valio, A.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Space Weather
Publisher:American Geophysical Union
ISSN (Online):1542-7390
Published Online:11 August 2018
Copyright Holders:Copyright © 2018 American Geophysical Union
First Published:First published in Space Weather 16(9): 1261-1268
Publisher Policy:Reproduced in accordance with the publisher copyright policy
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