The Mg II h&k lines as seen by IRIS: what do they tell us about the solar chromosphere? (Invited)
Abstract
NASA's Interface Region Imaging Spectrograph (IRIS) small explorer mission studies how the outer solar atmosphere is energized. IRIS contains an imaging spectrograph that covers the Mg II h&k lines as well as a slit-jaw imager centered at Mg II k. The Mg II h&k line cores form just below the transition region in the very upper chromosphere. These lines provide a unique diagnostic window on a region of the solar atmosphere that cannot be obtained with other spectral lines. I will describe what physical information can be obtained from Mg II h&k based on 3D numerical simulation of the solar atmosphere and non-LTE modeling of the h&k lines. The central line depression intensity and Doppler-shift provide information on the relative height of the transition region and the local gas velocity. Combining the h&k lines allows measurement of the local velocity gradient. The line-core emission peaks provide information on mid-chromospheric temperatures, velocities and the velocity gradient between the mid and upper chromosphere. I will show how to use these relations to analyze IRIS observations and discuss the results that have been obtained so far.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFMSH12A..04L
- Keywords:
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- 7507 SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY Chromosphere;
- 7500 SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY