Photospheric Magnetic Energy Input and the Atmospheric Response
Abstract
How are the chromospheres and coronae of the Sun and solar-like stars heated to much higher temperatures than their photospheres? Understanding atmospheric heating has been a major, unsolved problem in solar and stellar astrophysics for many decades now. Convective motions at the photosphere acting on the footpoints of coronal magnetic fields are presumed to inject magnetic energy into the Sun's atmosphere, where it is later released as heat. To investigate this hypothesis, the upward flux of magnetic energy across the photosphere --- quantified by the Poynting flux --- can be estimated by combining photospheric vector magnetic field measurements with horizontal photospheric velocities inferred by local correlation tracking (LCT) applied to magnetogram sequences. Recently published estimates of the net upward Poynting flux were roughly consistent with the expected energy demand required for chromospheric and coronal heating. But how are variations in magnetic energy injected across the photosphere related to variations in emission in the chromosphere, transition region, and corona? Comparisons between the estimated upward transport of magnetic energy and the atmospheric response are an essential step toward a comprehensive understanding of the physical processes that drive chromospheric and coronal heating. To address this issue, we have begun efforts to compare variations in chromospheric, transition region, and coronal emission observed by IRIS and SDO/AIA with estimates of the photospheric Poynting flux derived from sequential Hinode/SOT SpectroPolarimeter and Narrowband Filter Imager magnetograms of plage magnetic fields in active regions. Here, we will present initial results of our comparisons. This work is supported by NASA under contract NNG09FA40C (IRIS).
- Publication:
-
AAS/AGU Triennial Earth-Sun Summit
- Pub Date:
- April 2015
- Bibcode:
- 2015TESS....111105W