Extensive Study of a Coronal Mass Ejection with UV and WL coronagraphs: the need for multi-wavelength observations. (arXiv:2007.04575v1 [astro-ph.SR])

Extensive Study of a Coronal Mass Ejection with UV and WL coronagraphs: the need for multi-wavelength observations. (arXiv:2007.04575v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Ying_B/0/1/0/all/0/1">Beili Ying</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bemporad_A/0/1/0/all/0/1">Alessandro Bemporad</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Feng_L/0/1/0/all/0/1">Li Feng</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lu_L/0/1/0/all/0/1">Lei Lu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gan_W/0/1/0/all/0/1">Weiqun Gan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Li_H/0/1/0/all/0/1">Hui Li</a>

Coronal Mass Ejections (CMEs) often show different features in different
band-passes. By combining data in white-light (WL) and ultraviolet (UV) bands,
we have applied different techniques to derive plasma temperatures, electron
density, internal radial speed, etc, within a fast CME. They serve as extensive
tests of the diagnostic capabilities, developed for the observations provided
by future multi-channel coronagraphs (such as Solar Orbiter/Metis, ASO-S/LST,
PROBA-3/ASPIICS). The involved data include WL images acquired by SOHO/LASCO
coronagraphs, and intensities measured by SOHO/UVCS at 2.45 R$_{odot}$ in the
UV (H I Ly$alpha$ and O VI 1032 {AA} lines) and WL channels. Data from the
UVCS WL channel have been employed for the first time to measure the CME
position angle with polarization-ratio technique. Plasma electron and effective
temperatures of the CME core and void are estimated by combining UV and WL
data. Due to the CME expansion and the possible existence of prominence
segments, the transit of the CME core results in decreases of the electron
temperature down to $10^{5}$ K. The front is observed as a significant dimming
in the Ly$alpha$ intensity, associated with a line broadening due to plasma
heating and flows along the line-of-sight. The 2D distribution of plasma speeds
within the CME body is reconstructed from LASCO images and employed to
constrain the Doppler dimming of Ly$alpha$ line, and simulate future CME
observations by Metis and LST.

Coronal Mass Ejections (CMEs) often show different features in different
band-passes. By combining data in white-light (WL) and ultraviolet (UV) bands,
we have applied different techniques to derive plasma temperatures, electron
density, internal radial speed, etc, within a fast CME. They serve as extensive
tests of the diagnostic capabilities, developed for the observations provided
by future multi-channel coronagraphs (such as Solar Orbiter/Metis, ASO-S/LST,
PROBA-3/ASPIICS). The involved data include WL images acquired by SOHO/LASCO
coronagraphs, and intensities measured by SOHO/UVCS at 2.45 R$_{odot}$ in the
UV (H I Ly$alpha$ and O VI 1032 {AA} lines) and WL channels. Data from the
UVCS WL channel have been employed for the first time to measure the CME
position angle with polarization-ratio technique. Plasma electron and effective
temperatures of the CME core and void are estimated by combining UV and WL
data. Due to the CME expansion and the possible existence of prominence
segments, the transit of the CME core results in decreases of the electron
temperature down to $10^{5}$ K. The front is observed as a significant dimming
in the Ly$alpha$ intensity, associated with a line broadening due to plasma
heating and flows along the line-of-sight. The 2D distribution of plasma speeds
within the CME body is reconstructed from LASCO images and employed to
constrain the Doppler dimming of Ly$alpha$ line, and simulate future CME
observations by Metis and LST.

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