Direct Observations of Plasma Upflows and Condensation in a Catastrophically Cooling Solar Transition Region Loop

Abstract

Minimal observational evidence exists for fast transition region (TR) upflows in the presence of cool loops. Observations of such occurrences challenge notions of standard solar atmospheric heating models, as well as their description of bright TR emission. Using the {\it EUV Imaging Spectrometer} (EIS) onboard {\it Hinode}, we observe fast upflows ($v_{\lambda }$\,$\le$\,$-$10 km s${}^{-1}$) over multiple TR temperatures (5.8\,$\le$\,$\log T$\,$\le$ 6.0) at the footpoint sites of a cool loop ($\log T$\,$\le$\,6.0). Prior to cool loop energizing, asymmetric flows of $+$\,5 km s${}^{-1}$ and $-$\,60 km s${}^{-1}$ are observed at footpoint sites. These flows speeds and patterns occur simultaneously with both magnetic flux cancellation (at site of upflows only) derived from the {\it Solar Dynamics Observatory}'s (SDOs) { \it Helioseismic Magnetic Imager}'s (HMI) line-of-sight magnetogram images, and a 30\% mass in-flux at coronal heights. The incurred non-equilibrium structure of the cool loop leads to a catastrophic cooling event, with subsequent plasma evaporation indicating the TR as the heating site. From the magnetic flux evolution we conclude that magnetic reconnection between the footpoint and background field are responsible for observed fast TR plasma upflows.

10 pages, 8 figures

References in corpus (10)

• Highly Efficient Modeling of Dynamic Coronal Loops
• Observing the Roots of Solar Coronal Heating - in the Chromosphere
• Search for high velocities in the disk counterpart of type II spicules
• Observations of Active Region Loops with the EUV Imaging Spectrometer on Hinode
• The Role of Type II Spicules in the Upper Solar Atmosphere
• Observational Signatures of Simulated Reconnection Events in the Solar Chromosphere and Transition Region
• Evolution of microflares associated with bright points in coronal holes and in quiet regions
• Temporal Pointing Variations of The Solar Dynamics Observatory's HMI and AIA Instruments on Sub-Weekly Time Scales
• Observations and modeling of the emerging EUV loops in the quiet Sun as seen with the Solar Dynamics Observatory
• Comparative Analysis of a Transition Region Bright Point with a Blinker and Coronal Bright Point Using Multiple EIS Emission Lines

Cited by in corpus (4)

• Heating and cooling of coronal loops observed by SDO
• On the spectroscopic detection of periodic plasma flows in loops undergoing thermal non-equilibrium
• Observations of an Energetically Isolated Quiet Sun Transient: Evidence of Quasi-Steady Coronal Heating
• Solar Atmospheric Magnetic Energy Coupling: Broad Plasma Conditions and Spectrum Regimes