Tuesday, June 10 - Plenary Session

Name:  Bart De Pontieu

Affiliation:  Lockheed-Martin Solar & Astrophysics Lab.

Title:  The Solar Chromosphere and Transition Region as Viewed by the Interface Region Imaging Spectrograph (IRIS)

The Interface Region Imaging Spectrograph (IRIS) was launched in June 2013 and has been obtaining high-resolution (0.33 arcsec) spectra and images of the chromosphere and transition region since end of July 2013. I will describe the IRIS instrument and its diagnostics, which include strong lines in the far-ultraviolet (e.g., C II 1335, Si IV 1402) and near-ultraviolet (Mg II k 2796 and Mg II h 2803). I will present an overview of recent results based on IRIS observations, including: 1. detection of small-scale and dynamic transition region loops that were previously unresolved but whose existence had been hypothesized to explain the excess brightness in the transition region (so-called "unresolved fine structure"), 2. the pervasiveness of twist on very small scales in the chromosphere and transition region on a variety of different dynamic features and associated heating to transition region temperatures, 3. exploiting observations of the chromospheric response to coronal energy deposition to help constrain the coronal heating mechanism, 4. spatio-temporal characterization of the dominant heating mechanism in the chromosphere and its connection to that of the corona. Numerical simulations form an integral part of the IRIS science investigation. I will provide a comparison of IRIS observations with advanced radiative MHD simulations, which include the effects of ion-neutral interactions, and describe how such comparisons lead to new insights into the dynamics and energetics of the low solar atmosphere.