WHAT DO IRIS OBSERVATIONS OF Mg II k TELL US ABOUT THE SOLAR PLAGE CHROMOSPHERE?
Number of Authors: 3
2015 (English)In: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 809, no 2, L30Article in journal (Refereed) Published
We analyze observations from the Interface Region Imaging Spectrograph of the Mg II k line, the Mg II UV subordinate lines, and the O I 135.6 nm line to better understand the solar plage chromosphere. We also make comparisons with observations from the Swedish 1-m Solar Telescope of the H alpha line, the Ca II 8542 line, and Solar Dynamics Observatory/Atmospheric Imaging Assembly observations of the coronal 19.3 nm line. To understand the observed Mg II profiles, we compare these observations to the results of numerical experiments. The single-peaked or flat-topped Mg II k profiles found in plage imply a transition region at a high column mass and a hot and dense chromosphere of about 6500 K. This scenario is supported by the observed large-scale correlation between moss brightness and filled-in profiles with very little or absent self-reversal. The large wing width found in plage also implies a hot and dense chromosphere with a steep chromospheric temperature rise. The absence of emission in the Mg II subordinate lines constrain the chromospheric temperature and the height of the temperature rise while the width of the O I 135.6 nm line sets a limit to the non-thermal velocities to around 7 km s(-1).
Place, publisher, year, edition, pages
2015. Vol. 809, no 2, L30
Sun: atmosphere, Sun: chromosphere, Sun: faculae, plages
IdentifiersURN: urn:nbn:se:su:diva-121682DOI: 10.1088/2041-8205/809/2/L30ISI: 000360715500013OAI: oai:DiVA.org:su-121682DiVA: diva2:889671