Propagating brightenings in small loop-like structures in the quiet-Sun corona: Observations from Solar Orbiter/EUI

Propagating brightenings in small loop-like structures in the quiet-Sun corona: Observations from Solar Orbiter/EUI. Mandal, S., Peter, H., Pradeep Chitta, L., Solanki, S. K., Aznar Cuadrado, R., Teriaca, L., Schühle, U., Berghmans, D., & Auchère, F. Astronomy & Astrophysics, 656:L16, December, 2021.

Paper doi abstract bibtex

Brightenings observed in solar extreme-ultraviolet images are generally interpreted as signatures of micro- or nanoﬂares occurring in the transition region or at coronal temperatures. Recent observations with the Extreme Ultraviolet Imager (EUI) on board Solar Orbiter have revealed the smallest of such brightenings (called campﬁres) in the quiet-Sun corona. Analyzing EUI 174 Å data obtained at a resolution of about 400 km on the Sun with a cadence of 5 s on 30 May 2020, we report here a number of cases in which these campﬁres exhibit propagating signatures along their apparently small (3–5 Mm) loop-like structures. The measured propagation speeds are generally between 25 km s−1 and 60 km s−1. If the loop plasma is assumed to be at a million Kelvin, these apparent motions would be slower than the local sound speed. Furthermore, these brightenings exhibit nontrivial propagation characteristics such as bifurcation, merging, reﬂection, and repeated plasma ejections. We suggest that these features are manifestations of the internal dynamics of these small-scale magnetic structures and could provide important insights into the dynamic response (∼40 s) of the loop plasma to the heating events and also into the locations of the heating events themselves.

@article{mandal_propagating_2021,
	title = {Propagating brightenings in small loop-like structures in the quiet-{Sun} corona: {Observations} from {Solar} {Orbiter}/{EUI}},
	volume = {656},
	issn = {0004-6361, 1432-0746},
	shorttitle = {Propagating brightenings in small loop-like structures in the quiet-{Sun} corona},
	url = {https://www.aanda.org/10.1051/0004-6361/202142041},
	doi = {10.1051/0004-6361/202142041},
	abstract = {Brightenings observed in solar extreme-ultraviolet images are generally interpreted as signatures of micro- or nanoﬂares occurring in the transition region or at coronal temperatures. Recent observations with the Extreme Ultraviolet Imager (EUI) on board Solar Orbiter have revealed the smallest of such brightenings (called campﬁres) in the quiet-Sun corona. Analyzing EUI 174 Å data obtained at a resolution of about 400 km on the Sun with a cadence of 5 s on 30 May 2020, we report here a number of cases in which these campﬁres exhibit propagating signatures along their apparently small (3–5 Mm) loop-like structures. The measured propagation speeds are generally between 25 km s−1 and 60 km s−1. If the loop plasma is assumed to be at a million Kelvin, these apparent motions would be slower than the local sound speed. Furthermore, these brightenings exhibit nontrivial propagation characteristics such as bifurcation, merging, reﬂection, and repeated plasma ejections. We suggest that these features are manifestations of the internal dynamics of these small-scale magnetic structures and could provide important insights into the dynamic response (∼40 s) of the loop plasma to the heating events and also into the locations of the heating events themselves.},
	language = {en},
	urldate = {2022-07-12},
	journal = {Astronomy \& Astrophysics},
	author = {Mandal, Sudip and Peter, Hardi and Pradeep Chitta, Lakshmi and Solanki, Sami K. and Aznar Cuadrado, Regina and Teriaca, Luca and Schühle, Udo and Berghmans, David and Auchère, Frédéric},
	month = dec,
	year = {2021},
	pages = {L16},
}

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