2023/09/12 by Pradeep Kayshap, Peter R. Young, Kayshap, Pradeep +1 · 1 citation
Physics and Astronomy · #Astrophysics and Star Formation Studies #FOS: Physical sciences #Solar and Space Plasma Dynamics #Solar and Stellar Astrophysics (astro-ph.SR) #Stellar, planetary, and galactic studies
paper · pdf · doi:10.48550/arxiv.2309.06360
openalex publication_date 2023/09/12 · openalex created_date 2023/09/14 · openalex updated_date 2026/07/28
The center-to-limb variations (CLV) of Gaussian fit parameters of the transition region Si~\sc iv 1402.77~Å spectral line in quiet Sun (QS) and coronal hole (CH) regions are presented. The results are derived from a full-disk mosaic scan obtained by the Interface Region Imaging Spectrograph on 24 September 2017. The CLV for a CH transition region line has not previously been reported, and the parameters are found to show variations consistent with the QS. The intensity increases towards the limb, consistent with an increasing plasma column depth due to line-of-sight effects. The Doppler velocity is normalized to be zero at the limb for both QS and CH and increases to +4.8~\kms (redshift) at disk center for CH and +5.2~\kms for QS. Non-thermal broadening in the CH decreases from a maximum of 24~\kms at the limb to 10~\kms at disk center. For QS the broadening decreases from 25~\kms at the limb to 14~\kms at disk center. Both Doppler velocities and non-thermal velocities vary linearly with cos θ, where θ is the heliocentric angle. The QS results for both parameters are consistent with earlier work.