Estimation of Solar Prominence Magnetic Fields Based on the Reconstructed 3D Trajectories of Prominence Knots

Abstract

We present an estimation of the lower limits of local magnetic field strengths in quiescent, activated, and active (surges) prominences, based on reconstructed threedimensional (3D) trajectories of individual prominence knots. The 3D trajectories, velocities, tangential and centripetal accelerations of the knots were reconstructed using observational data collected with a single ground-based telescope equipped with a Multi-channel Subtractive Double Pass imaging spectrograph. Lower limits of magnetic fields channeling observed plasma flows were estimated under assumption of the equipartition principle. Assuming approximate electron densities of the plasma n e = 5 × 10 11 cm −3 in surges and n e = 5 × 10 10 cm −3 in quiescent/activated prominences, we found that the magnetic fields channeling two observed surges range from 16 to 40 Gauss, while in quiescent and activated prominences they were less than 10 Gauss. Our results are consistent with previous detections of weak local magnetic fields in the solar prominences.

Reconstruction of a helical prominence in 3D from IRIS spectra and images

“…Using the 3D trajectory reconstruction method described in Zapiór & Rudawy (2012), the positions of 15 knots in x and y are computed by polynomial approximations. Only nine knots are shown in the bottom right panel of Figure 10 for clarity.…”

“…Helical motions have been detected in prominences (Martínez González et al 2015;Zapiór & Martínez-Gómez 2016). For example, knot trajectories along elliptical loops have been computed using a method of 3D reconstruction developed in Zapiór & Rudawy (2012). We shall use the same method in the present paper.…”

Coronal Magnetic Fields Derived with Images Acquired during the 2017 August 21 Total Solar Eclipse

“…Values of the magnetic field (or at least a lower limit of it, considering other energies being neglected) can be derived from the above simple relationship, once the plasma density ρ and velocity v are known. This equality has been assumed for the measurement of magnetic fields in the solar photosphere (e.g., Beckers 1971), and in prominences from the observations of moving blobs (e.g., Ballester & Kleczek 1984), or knots (Zapiór & Rudawy 2012;Zapiór & Martínez-Gómez 2016), hence in regimes where β > 1. An equipartition between magnetic and kinetic energy densities also holds for Alfvén waves (e.g., Cranmer & van Ballegooijen 2005) in the corona.…”

Comparison of magnetic fields in quiescent solar prominences measured by D3 HeI and Hα lines

“…позже эти данные о столь сильных полях не подтвердились: по измерениям со спектросканирующим магнитографом, в протуберанцах B 30 Гс [9]. Последующие измерения приводили к оценкам от нескольких десятков гаусс [7,8,15,17] до 1000 Гс [4,16]. Последнее значение получено для активного и яркого протуберанца, содержащего в спектре много узких линий металлов [4] и активного участка волокна в фотосфере [16].…”