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Spectroscopic He I 1083 nm prominence eruption observations in the middle corona with MLSO/UCoMP

Chloe Pistelli, Momchil E Molnar, Giuliana de Toma, Joseph Plowman

TL;DR

This paper assesses the feasibility of using ground-based He I 1083 nm spectropolarimetry to study erupting prominences embedded in CMEs in the middle corona. Using commissioning-phase data from UCoMP, complemented by K-Cor and AIA context imaging, the authors demonstrate that prominences are bright in He I 1083 nm and detectable up to the instrument's field of view during eruptions, enabling estimates of line-of-sight velocities. They discuss instrument limitations such as saturation and background subtraction, and they assess the association rate of He I 1083 nm eruptions with LASCO CMEs, underscoring the potential and constraints for near-term space weather diagnostics. Overall, the results establish He I 1083 nm observations as a robust supplementary diagnostic for CME evolution and a path toward ground-based, near real-time space weather forecasting when integrated with other observatories.

Abstract

Coronal mass ejections (CMEs) are a major driver of space weather as they propagate through the heliosphere. Many CMEs have associated prominence material entangled in their magnetic structure which contains cooler plasma. This cooler CME component contains significant amounts of neutral elements, which emit brightly in permitted atomic lines. It has been hypothesized that permitted transitions of neutral elements in eruptions could be used for inferring the magnetic field in CMEs, which is crucial for space weather forecasting. We present observations made with the Upgraded Coronal Multi-channel Polarimeter (UCoMP) in He I 1083 nm that clearly show the presence of neutral helium in eruptive prominences associated with CMEs as they propagate through the lower and middle corona. We find that solar prominence eruptions can be detected in He I 1083 nm observations up to the edge of the instrument field of view at about 2 solar radii, providing valuable spectral information that complements existing extreme ultraviolet and white-light coronal imaging observatories. These results illustrate the capability of UCoMP to probe the dynamic behavior of prominence eruptions, allowing for their line-of-sight velocity estimation, and potentially improving space weather forecasting by enabling earlier and more accurate identification of Earth-directed eruptions.

Spectroscopic He I 1083 nm prominence eruption observations in the middle corona with MLSO/UCoMP

TL;DR

This paper assesses the feasibility of using ground-based He I 1083 nm spectropolarimetry to study erupting prominences embedded in CMEs in the middle corona. Using commissioning-phase data from UCoMP, complemented by K-Cor and AIA context imaging, the authors demonstrate that prominences are bright in He I 1083 nm and detectable up to the instrument's field of view during eruptions, enabling estimates of line-of-sight velocities. They discuss instrument limitations such as saturation and background subtraction, and they assess the association rate of He I 1083 nm eruptions with LASCO CMEs, underscoring the potential and constraints for near-term space weather diagnostics. Overall, the results establish He I 1083 nm observations as a robust supplementary diagnostic for CME evolution and a path toward ground-based, near real-time space weather forecasting when integrated with other observatories.

Abstract

Coronal mass ejections (CMEs) are a major driver of space weather as they propagate through the heliosphere. Many CMEs have associated prominence material entangled in their magnetic structure which contains cooler plasma. This cooler CME component contains significant amounts of neutral elements, which emit brightly in permitted atomic lines. It has been hypothesized that permitted transitions of neutral elements in eruptions could be used for inferring the magnetic field in CMEs, which is crucial for space weather forecasting. We present observations made with the Upgraded Coronal Multi-channel Polarimeter (UCoMP) in He I 1083 nm that clearly show the presence of neutral helium in eruptive prominences associated with CMEs as they propagate through the lower and middle corona. We find that solar prominence eruptions can be detected in He I 1083 nm observations up to the edge of the instrument field of view at about 2 solar radii, providing valuable spectral information that complements existing extreme ultraviolet and white-light coronal imaging observatories. These results illustrate the capability of UCoMP to probe the dynamic behavior of prominence eruptions, allowing for their line-of-sight velocity estimation, and potentially improving space weather forecasting by enabling earlier and more accurate identification of Earth-directed eruptions.
Paper Structure (7 sections, 7 figures)

This paper contains 7 sections, 7 figures.

Table of Contents

  1. Introduction
  2. Observations from the UCoMP Commissioning Phase
  3. UCoMP Data
  4. Context imaging during the UCoMP commissioning campaign: K-Cor and AIA
  5. Properties of prominence eruptions as observed in the He$\;$ 1083 line
  6. Discussion
  7. Conclusions

Figures (7)

  • Figure 1: A context illustration of the solar eruption on 2021 July 15; panel (a): MLSO/K-COR white light coronagraph difference image at 22:05:25 UT; panel (b): UCoMP He$\;$1083 line core intensity at 21:53:22 UT; panel (c): SDO/AIA 211,193,171 Å RGB composite from the AIA LMSAL webpage at 21:55:46 UT; panel (d): SOHO/LASCO C3 coronograph white light image at 02:42:05 UT on 2021 July 16. The red arrow in the K-COR and SDO/AIA plots point to the observed eruption. The red rectangular box in the K-Cor plot represents the field of view of UCoMP.
  • Figure 2: Transmission of the UCoMP Lyot filter in the He$\;$ 1083 window. The on-band channel corresponds to the blue curve with a single peak, whereas the off-band channel, used for the background subtraction, is shown in orange and has a double peaked profile.
  • Figure 3: Intensity of the prominence eruption on 2021 July 15 across the He$\;$ 1083 spectral line in units of millionths of disc brightness ($\mu$B). The top row shows the on-band data, and the bottom row shows the off-band continuum channel. The Doppler velocities in the bottom panel of Figure 3 correspond a wavelength shift equal to the difference between the He$\;$1083 line peak and the wavelength at which the off-band image was tuned. They are intended to be a guide to the reader and we do not imply them to be present in the emitting plasma. Due to the non-linear camera detection regime of the bright prominence, the intensity estimates are lower bounds of the real intensities.
  • Figure 4: Intensity of the solar eruption on 2021 July 30 across the He$\;$ 1083 spectral line window in units of millionths of disc brightness ($\mu$B). The same caveats for the data presented in Figure \ref{['fig:amp_figure_20210715']} apply.
  • Figure 5: Same as Figure \ref{['fig:amp_figure_20210730']} for the prominence eruption observed on 2021 August 28.
  • ...and 2 more figures