Launch of a CME-associated eruptive prominence as observed with IRIS and ancillary instruments

P Zhang,É Buchlin,J.-C Vial

doi:10.1051/0004-6361/201834259

Abstract

Aims. In this paper we focus on the possible observational signatures of the processes which have been put forward for explaining eruptive prominences. We also try to understand the variations in the physical conditions of eruptive prominences and estimate the masses leaving the Sun versus the masses returning to the Sun during eruptive prominences.Methods. As far as velocities are concerned, we combined an optical flow method on the Atmospheric Imaging Assembly (AIA) 304 Å and Interface Region Imaging Spectrograph (IRIS). Mg IIh&k observations in order to derive the plane-of-sky velocities in the prominence, and a Doppler technique on the IRIS Mg IIh&k profiles to compute the line-of-sight velocities. As far as densities are concerned, we compared the absolute observed intensities with values derived from non-local thermodynamic equilibrium radiative transfer computations to derive the total (hydrogen) density and consequently compute the mass flows.Results. The derived electron densities range from 1.3 × 109to 6.0 × 1010cm−3and the derived total hydrogen densities range from 1.5 × 109to 2.4 × 1011cm−3in different regions of the prominence. The mean temperature is around 1.1 × 104K, which is higher than in quiescent prominences. The ionization degree is in the range of 0.1–10. The total (hydrogen) mass is in the range of 1.3 × 1014–3.2 × 1014g. The total mass drainage from the prominence to the solar surface during the whole observation time of IRIS is about one order of magnitude smaller than the total mass of the prominence.

Highlights

The issues of formation, stability, and eruption of solar prominences are very actively explored for many reasons ranging from the unanswered questions they raise in plasma physics to space weather aspects because of the close link between prominence eruptions (PEs), flares, and coronal mass ejections (CMEs); a recent overview can be found in Vial & Engvold (2015)
Much progress has been made in the last decades with the advent of both synoptic measurements from space (with the Extreme ultraviolet Imaging Telescope (EIT) onboard the Solar and Heliospheric Observatory (SOHO), the Atmospheric Imaging Assembly (AIA) telescope onboard the Solar Dynamics Observatory (SDO) and the Extreme-Ultraviolet Imagers (EUVI) on the Sun-Earth Connection Coronal and Heliospheric Investigation (SECCHI) suite of telescopes onboard the Solar Terrestrial Relations Observatory (STEREO)) and multiwavelength spectroimaging
We find profiles that have more than two peaks, which indicate a combination of different structures with different velocities along the LOS

Summary

Introduction

The issues of formation, stability, and eruption of solar prominences are very actively explored for many reasons ranging from the unanswered questions they raise in plasma physics to space weather aspects because of the close link between prominence eruptions (PEs), flares, and coronal mass ejections (CMEs); a recent overview can be found in Vial & Engvold (2015). Simultaneous full-disk He ii 304 Å observations with 1 min cadence were made by the Atmospheric Imaging Assembly (AIA, Lemen et al 2012) of the Solar Dynamics Observatory (SDO, Pesnell et al 2012), together with six other extreme ultraviolet (EUV) spectral channels The He ii 304 Å channel was chosen as being sensitive to chromosphere and transition region temperatures, and most representative of the cool prominence material. The top of the prominence reaches the of AIA FOV boundary around 19:10 UT Afterwards it is continuously tracked in K-COR images in white light, this does not necessarily correspond to the same features as seen in the 304 Å channel. Zhang et al.: Launch of a CME-associated eruptive prominence as observed with IRIS and ancillary instruments top at 15:17 and 19:34 UT are on the order of 5 to 20 km s−1 They are consistent with the results of prominence top tracking They are consistent with the results of prominence top tracking (Sect. 3.2.1)

Doppler velocities

Findings

Discussion and conclusions