Observations of Ray-Like Structures in Large-Scale Coronal Dimmings Produced by Limb CMEs. (arXiv:2003.11326v1 [astro-ph.SR])

Observations of Ray-Like Structures in Large-Scale Coronal Dimmings Produced by Limb CMEs. (arXiv:2003.11326v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Goryaev_F/0/1/0/all/0/1">F. Goryaev</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Slemzin_V/0/1/0/all/0/1">V. Slemzin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rodkin_D/0/1/0/all/0/1">D. Rodkin</a>

Observations of the off-limb corona with the SWAP wide-field telescope in the
174,AA passband onboard the PROBA2 mission provide an opportunity to study
post-eruptive processes in the dimming regions. We investigate morphology,
temporal evolution, and plasma properties for four `deep’ off-disk coronal
dimmings associated with limb coronal mass ejections (CMEs) in 2010,–,2017.
Using the SWAP fixed-difference images, we revealed ray-like structures that
appeared in the dimming recovery phase stretching quasi-radially to distances
from 1.1 to 1.6,$mathrm{R}_{odot}$ and existing from tens of minutes to
several hours. Similar rays were detected earlier at distances above
1.7,$mathrm{R}_{odot}$ by the UVCS onboard the SOHO. These structures
apparently represent the coronal roots of the flux rope trunks observed by the
LASCO-C2 onboard SOHO. The EUVI data onboard the STEREO show the origins of
these structures on the disc as fan rays much brighter in the 171,AA band
than in 193,AA , which suggests their temperature being less than 2,MK. The
differential emission measure (DEM) analysis based on the AIA multi-wavelength
images onboard the SDO showed that the emission measure (EM) in these rays
compared to the pre-eruption plasma state increased up to 45,% at
temperatures of 0.6,–,0.8,MK, whereas EM of the ambient coronal plasma with
temperatures of 1.3,–,3.7,MK dropped by 19,–,43,%. For the event on 18
August 2010, the PLASTIC instrument onboard STEREO detected signatures of the
cold streams in the CME tail as enriched with the ions
Fe$^{8+}$,–,Fe$^{10+}$, which may be associated with the post-eruptive rays
in the solar corona.

Observations of the off-limb corona with the SWAP wide-field telescope in the
174,AA passband onboard the PROBA2 mission provide an opportunity to study
post-eruptive processes in the dimming regions. We investigate morphology,
temporal evolution, and plasma properties for four `deep’ off-disk coronal
dimmings associated with limb coronal mass ejections (CMEs) in 2010,–,2017.
Using the SWAP fixed-difference images, we revealed ray-like structures that
appeared in the dimming recovery phase stretching quasi-radially to distances
from 1.1 to 1.6,$mathrm{R}_{odot}$ and existing from tens of minutes to
several hours. Similar rays were detected earlier at distances above
1.7,$mathrm{R}_{odot}$ by the UVCS onboard the SOHO. These structures
apparently represent the coronal roots of the flux rope trunks observed by the
LASCO-C2 onboard SOHO. The EUVI data onboard the STEREO show the origins of
these structures on the disc as fan rays much brighter in the 171,AA band
than in 193,AA , which suggests their temperature being less than 2,MK. The
differential emission measure (DEM) analysis based on the AIA multi-wavelength
images onboard the SDO showed that the emission measure (EM) in these rays
compared to the pre-eruption plasma state increased up to 45,% at
temperatures of 0.6,–,0.8,MK, whereas EM of the ambient coronal plasma with
temperatures of 1.3,–,3.7,MK dropped by 19,–,43,%. For the event on 18
August 2010, the PLASTIC instrument onboard STEREO detected signatures of the
cold streams in the CME tail as enriched with the ions
Fe$^{8+}$,–,Fe$^{10+}$, which may be associated with the post-eruptive rays
in the solar corona.

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