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<p>We present Aditya-L1/VELC spectroscopic observations of 5303Å coronal emission line widths before and after coronal mass ejections (CMEs) which showed coronal dimming. The sit &amp; stare mode of observations enabled us to study the changes in the line widths for the ‘limb’ CMEs noticed on 16 July 2024 and 05 August 2024. The emission line widths during the pre-CME phase are higher than the thermal values in both the cases. After the onset of the CMEs, the widths increased further by <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\({\approx }15\%\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo>≈</mo> <mn>15</mn> <mo>%</mo> </mrow> </math></EquationSource> </InlineEquation> on 16 July 2024 and <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\({\approx }7\%\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo>≈</mo> <mn>7</mn> <mo>%</mo> </mrow> </math></EquationSource> </InlineEquation> on 05 August 2024. We find that the power spectral density (PSD) distributions of the line widths for the two events exhibits a power-law behavior. The PSD slopes, measured before and after the CMEs are nearly the same, and close to the Kolmogorov slope of <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\({-5/3}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo>-</mo> <mn>5</mn> <mo stretchy="false">/</mo> <mn>3</mn> </mrow> </math></EquationSource> </InlineEquation>. The results suggest that the observed larger than thermal width of the 5303Å emission line, before and after CMEs, is mostly due to turbulence. The additional increase in the line widths after the onset of the CMEs in both the cases are likely because of enhanced turbulence caused by the CME associated coronal dimmings and subsequent coronal magnetic field reconfiguration.</p>

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Aditya-L1/VELC observations of CME associated broadening of 5303Å coronal emission line

  • 期刊论文

  • 发表日期：

    2026年7月22日

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  • K Sasikumar Raja,
  • V Muthu Priyal,
  • R Ramesh,
  • Jagdev Singh,
  • Prasad Subramanian

摘要

We present Aditya-L1/VELC spectroscopic observations of 5303Å coronal emission line widths before and after coronal mass ejections (CMEs) which showed coronal dimming. The sit & stare mode of observations enabled us to study the changes in the line widths for the ‘limb’ CMEs noticed on 16 July 2024 and 05 August 2024. The emission line widths during the pre-CME phase are higher than the thermal values in both the cases. After the onset of the CMEs, the widths increased further by \({\approx }15\%\) ≈ 15 % on 16 July 2024 and \({\approx }7\%\) ≈ 7 % on 05 August 2024. We find that the power spectral density (PSD) distributions of the line widths for the two events exhibits a power-law behavior. The PSD slopes, measured before and after the CMEs are nearly the same, and close to the Kolmogorov slope of \({-5/3}\) - 5 / 3 . The results suggest that the observed larger than thermal width of the 5303Å emission line, before and after CMEs, is mostly due to turbulence. The additional increase in the line widths after the onset of the CMEs in both the cases are likely because of enhanced turbulence caused by the CME associated coronal dimmings and subsequent coronal magnetic field reconfiguration.