000006963 001__ 6963
000006963 005__ 20240415135615.0
000006963 037__ $$aCTALK-2024-0112
000006963 100__ $$aVanden Broeck, Grégory
000006963 245__ $$aComparison of the magnetic structures in full-disk solar Ca II K images and Sun-as-a-star S-Index
000006963 260__ $$c2023
000006963 269__ $$c2023-07-13
000006963 520__ $$aThe chromospheric emission in the Ca II K line is a primary tracer of magnetic activity in the Sun and other Sun-like stars. Our goal is to study the long-term brightness variation of the chromosphere in this line, taking into account the different chromospheric structures (plages, network, sunspots). Those structures are the main contributors to the variability of the solar irradiance, which plays a important role in the chemistry of the Earth atmosphere. For this, we exploit the archives of synoptic full-disc images taken at the Royal Observatory of Belgium with the Uccle Solar Equatorial Table (USET). Ca II K images were recorded since 2012, allowing us to study the second half of the cycle 24 and the beginning of the cycle 25. We first describe the methods to determine the area fraction covered by bright plages, based on the USET images. In a Sun-as-a-star approach, we then compare our results with the S-index data from the TIGRE telescope, located in Guanajuato, Mexico, observing the integrated solar spectrum reflected by the Moon. The S-index measures the magnetic activity in stars and is calculated as the ratio of the flux in two spectral lines, Ca II H and K, which are sensitive to magnetic activity in stars. Our solar Ca II K images can thus serve as a "Rosetta stone" to study the similar mechanisms acting in other sun-like stars.
000006963 594__ $$aNO
000006963 6531_ $$aSun: activity
000006963 6531_ $$aSun: chromosphere
000006963 6531_ $$aSun: plages
000006963 6531_ $$aSun: Sun-as-a-star
000006963 6531_ $$aSun: rotation period
000006963 6531_ $$aStar: S-Index
000006963 700__ $$aBechet, Sabrina
000006963 700__ $$aRauw, Gregor
000006963 700__ $$aClette, Frédéric
000006963 773__ $$tInternational Union of Geodesy and Geophysics, Berlin, Germany
000006963 8560_ $$fgregory.vandenbroeck@ksb-orb.be
000006963 8564_ $$s15299549$$uhttp://publi2-as.oma.be/record/6963/files/IUGG2023_VandenBroeck_Gregory.pptx$$yPowerpoint of the oral presentation
000006963 906__ $$aContributed
000006963 980__ $$aCTALKCONT