The spectroscopic imprint of the pre-eruptive configuration resulting into two major coronal mass ejections

Abstract

We present a spectroscopic analysis of the pre-eruptive configuration of active region NOAA 11429, prior to two very fast coronal mass ejections (CMEs) on March 7, 2012 that are associated with this active region. We study the thermal components and the dynamics associated with the ejected flux ropes. Using differential emission measure (DEM) analysis of Hinode/EIS and SDO/AIA observations, we identify the emission components of both the flux rope and the host active region. We then follow the time evolution of the flux rope emission components by using AIA observations. The plasma density and the Doppler and non-thermal velocities associated with the flux ropes are also calculated from the EIS data. The eastern and western parts of the active region, in which the two different fast CMEs originated during two X-class flares, were studied separately. In both regions we identified an emission component in the temperature range of $\log T=6.8-7.1$ associated with the presence of flux ropes. The time evolution of the eastern region showed an increase in the mean DEM in this temperature range by an order of magnitude, 5 hours prior to the first CME. This was associated with a gradual rise and heating of the flux rope as manifested by blue-shifts and increased non-thermal velocities in \ion{Ca}{XV}~200.97Å, respectively. An overall upward motion of the flux ropes was measured (relative blue-shifts of $\sim 12$~\kms). The measured electron density was found to be $4\times 10^9-2\times 10^{10}$ cm${}^{-3}$ (using the ratio of \ion{Ca}{XV}~181.90Å over \ion{Ca}{XV}~200.97Å). We compare our findings with other works on the same AR to provide a unified picture of its evolution.

14 pages, 12 figures, 4 tables

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• Origin and Structures of Solar Eruptions I: Magnetic Flux Rope (Invited Review)
• Non-neutralized electric currents in solar active regions and flare productivity
• Transient Inverse-FIP Plasma Composition Evolution within a Confined Solar Flare
• Analysis and modelling of recurrent solar flares observed with Hinode/EIS on March 9, 2012
• Recurrent CME-like eruptions in emerging flux regions. I. On the mechanism of eruptions
• Which Photospheric Characteristics are Most Relevant to Active-Region Coronal Mass Ejections?
• When do solar erupting hot magnetic flux ropes form?
• The emergence of magnetic flux and its role on the onset of solar dynamic events
• Spectroscopic diagnostics of the non-Maxwellian $\kappa$-distributions using SDO/EVE observations of the 2012 March 7 X-class flare
• The characteristics of flare- and CME-productive solar active regions
• Influence of coronal holes on CME deflections: numerical study
• A new trigger mechanism for coronal mass ejections: the role of confined flares and photospheric motions in the formation of hot flux ropes
• Eruptions and Flaring Activity in Emerging Quadrupolar Regions
• Modeling of the sunspot-associated microwave emission using a new method of DEM inversion
• Spectroscopic Diagnostics of Solar Magnetic Flux Ropes Using Iron Forbidden Line
• Recurrent CME-like Eruptions in Emerging Flux Regions. II. Scaling of Energy and Collision of Successive Eruptions