Characteristics of the Solar Coronal Line Profiles from Fabry–Perot Interferometric Observations

Abstract

This article reports the analysis of a set of Fabry-Perot interferograms that were studied to probe the physical parameters of the inner solar corona. The observations were carried out in the coronal green line, Fe XIV 5302.86Å, during the total solar eclipse of 21 June 2001 which occurred in Lusaka, Zambia. The study was performed in the radial range of 1.1-1.5 R ⊙ and examines the Doppler velocity, halfwidth, centroid and asymmetry and their correlations with each other at various points in the corona. It is found that 59 % of the line profiles are blueshifted, 34 % of them are single components and only 7 % of them are redshifted. The variations of halfwidth and Doppler velocity with respect to coronal height have a large scatter and shows no significant changes. It has been found that the variations of halfwidth with Doppler velocity or centroid follow a parabolic trend with a weak correlation, whereas the relation between halfwidth and the asymmetry is inconclusive. These results may provide more insight to the coronal dynamics and help in understanding the coronal physical problems.

Line Profile Studies of Coronal Active Regions in Fe xii λ195.12 Using Hinode/EIS

“…The aim of the paper is to study the coronal active regions using the emission-line profiles. In our earlier work (Prabhakar et al 2019) we found some correlation of the line width with the Doppler velocity and the centroid. This is from the ground-based eclipse observations that lasted for just 3 minutes and 37 s. Hinode also provides a great opportunity to study the long-term behavior of the corona.…”

“…It can be seen that the variation is not linear but can be fitted with a higher-degree polynomial. As seen from our earlier paper (Prabhakar et al 2019), a second-degree polynomial gives a good fitting, and there is no substantial improvement in a thirddegree polynomial fit. It can also be seen that the estimated velocities and centroids in the single Gaussian fit are much smaller than the actual values.…”

“…In Prabhakar et al (2019), these authors have reported 59% blueshifts and only 7% redshifts of the Doppler velocity in the coronal green line profiles. However, in the present study, we see an almost equal distribution of blueshifts and redshifts in the Doppler velocity.…”

“…Figures 12(a versus Doppler velocity and line width versus centroid distributions of different data sets. We have earlier studied the correlation between these quantities from ground-based eclipse observation of the coronal green line Fe XIV λ5303 and found that a quadratic polynomial gives the best fit (Prabhakar et al 2019). Therefore, we have tried the quadratic polynomial fits here.…”

2023 Astrophotonics Roadmap: pathways to realizing multi-functional integrated astrophotonic instruments

“…The cavity transmits a discrete set of modes, with wavelengths and line widths dictated by basic properties of the cavity such as mirror spacing, mirror reflectivity, and refractive index of the cavity medium. It is these transmitted modes that can serve as calibration features for a variety of spectroscopic applications, ranging from laser stabilization [446] to stellar spectroscopy [447][448][449]. In astronomy, FPEs have most recently been used as highly precise wavelength calibration references for high resolution, broadband Echelle spectrometers, as they are capable of producing sharp spectral features across wide wavelength ranges.…”