First high-resolution spectroscopic observations of an erupting prominence within a coronal mass ejection by the Interface Region Imaging Spectrograph (IRIS)

Liu, Wei, De Pontieu, Bart, Vial, Jean-Claude, Title, Alan M., Carlsson, Mats, Uitenbroek, Han, Okamoto, Takenori J., Berger, Thomas E. and Antolin, Patrick (2015) First high-resolution spectroscopic observations of an erupting prominence within a coronal mass ejection by the Interface Region Imaging Spectrograph (IRIS). The Astrophysical Journal, 803 (2). p. 85. ISSN 0004-637X

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Official URL: https://doi.org/10.1088/0004-637X/803/2/85

Abstract

Spectroscopic observations of prominence eruptions associated with coronal mass ejections (CMEs), although relatively rare, can provide valuable plasma and three-dimensional geometry diagnostics. We report the first observations by the Interface Region Imaging Spectrograph mission of a spectacular fast CME/prominence eruption associated with an equivalent X1.6 flare on 2014 May 9. The maximum plane-of-sky and Doppler velocities of the eruption are 1200 and 460 km s−1, respectively. There are two eruption components separated by ~200 km s−1 in Doppler velocity: a primary, bright component and a secondary, faint component, suggesting a hollow, rather than solid, cone-shaped distribution of material. The eruption involves a left-handed helical structure undergoing counterclockwise (viewed top-down) unwinding motion. There is a temporal evolution from upward eruption to downward fallback with less-than-free-fall speeds and decreasing nonthermal line widths. We find a wide range of Mg ii k/h line intensity ratios (less than ~2 expected for optically-thin thermal emission): the lowest ever reported median value of 1.17 found in the fallback material, a comparably high value of 1.63 in nearby coronal rain, and intermediate values of 1.53 and 1.41 in the two eruption components. The fallback material exhibits a strong (>5α ) linear correlation between the k/h ratio and the Doppler velocity as well as the line intensity. We demonstrate that Doppler dimming of scattered chromospheric emission by the erupted material can potentially explain such characteristics.

Item Type: Article
Uncontrolled Keywords: Sun: activity, Sun: corona, Sun: coronal mass ejections: CMEs, Sun: filaments, Prominences, Sun: UV radiation
Subjects: F300 Physics
F500 Astronomy
Department: Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering
Depositing User: Elena Carlaw
Date Deposited: 25 Oct 2019 15:16
Last Modified: 25 Oct 2019 15:30
URI: http://nrl.northumbria.ac.uk/id/eprint/41256

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