{"id":1949,"date":"2022-07-07T07:50:22","date_gmt":"2022-07-07T06:50:22","guid":{"rendered":"https:\/\/pepsi.aip.de\/?p=1949"},"modified":"2022-07-07T07:53:11","modified_gmt":"2022-07-07T06:53:11","slug":"characterization-of-chromospheric-activity-based-on-sun%e2%80%91as%e2%80%91a%e2%80%91star-spectral-and-disk%e2%80%91resolved-activity-indices","status":"publish","type":"post","link":"https:\/\/pepsi.aip.de\/?p=1949","title":{"rendered":"Characterization of chromospheric activity based on Sun\u2011as\u2011a\u2011star  spectral and disk\u2011resolved activity indices"},"content":{"rendered":"\n<p>The strong chromospheric absorption lines Ca H &amp; K are tightly connected to stellar surface magnetic fields. Only for the Sun, spectral activity indices can be related to evolving magnetic features on the solar disk. The Solar Disk-Integrated (SDI) telescope feeds the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) of the Large Binocular Telescope (LBT) at Mt. Graham International Observatory (MGIO), Arizona, U.S.A. We present high-resolution, high-fidelity spectra that were recorded on 184 &amp; 82 days in 2018 &amp; 2019 and derive the Ca H &amp; K emission ratio, i.e., the S-index. In addition, we compile excess brightness and area indices based on full-disk Ca K line-core filtergrams of the Chromospheric Telescope (ChroTel) at Observatorio del Teide, Tenerife, Spain and full-disk ultraviolet (UV) 1600 \u00c5 images of the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). Thus, Sun-as-a-star spectral indices are related to their counterparts derived from resolved images of the solar chromosphere. All indices display signatures of rotational modulation, even during the very low magnetic activity in the minimum of Solar Cycle 24. Bringing together different types of activity indices has the potential to join disparate chromospheric datasets, yielding a comprehensive description of chromospheric activity across many solar cycles.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"570\" src=\"https:\/\/pepsi.aip.de\/wp-content\/uploads\/2022\/07\/Sun-as-a-star-1024x570.png\" alt=\"\" class=\"wp-image-1948\" srcset=\"https:\/\/pepsi.aip.de\/wp-content\/uploads\/2022\/07\/Sun-as-a-star-1024x570.png 1024w, https:\/\/pepsi.aip.de\/wp-content\/uploads\/2022\/07\/Sun-as-a-star-300x167.png 300w, https:\/\/pepsi.aip.de\/wp-content\/uploads\/2022\/07\/Sun-as-a-star-768x427.png 768w, https:\/\/pepsi.aip.de\/wp-content\/uploads\/2022\/07\/Sun-as-a-star-1536x855.png 1536w, https:\/\/pepsi.aip.de\/wp-content\/uploads\/2022\/07\/Sun-as-a-star-2048x1140.png 2048w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption>(a) Average Ca II H &amp; K spectrum computed from 60 consecutive exposures obtained by PEPSI\/SDI on June 21, 2018. Details of the line fitting procedure are shown in the \u00b11.2 \u00c5 range around the cores of (b) the Ca II K and (c) the Ca II H chromospheric absorption lines. <\/figcaption><\/figure>\n\n\n\n<p>Read more: <a href=\"https:\/\/ui.adsabs.harvard.edu\/abs\/2022AN....34323996D\/abstract\">Dineva et al. 2022, AN 343, article id e23996<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>The strong chromospheric absorption lines Ca H &amp; K are tightly connected to stellar surface magnetic fields. Only for the Sun, spectral activity indices can be related to evolving magnetic features on the solar disk. The Solar Disk-Integrated (SDI) telescope feeds the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) of the Large Binocular Telescope (LBT) &hellip; <a href=\"https:\/\/pepsi.aip.de\/?p=1949\" class=\"more-link\">Continue reading <span class=\"screen-reader-text\">Characterization of chromospheric activity based on Sun\u2011as\u2011a\u2011star  spectral and disk\u2011resolved activity indices<\/span> <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":5,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[11],"tags":[],"class_list":["post-1949","post","type-post","status-publish","format-standard","hentry","category-publications"],"_links":{"self":[{"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=\/wp\/v2\/posts\/1949","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1949"}],"version-history":[{"count":3,"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=\/wp\/v2\/posts\/1949\/revisions"}],"predecessor-version":[{"id":1952,"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=\/wp\/v2\/posts\/1949\/revisions\/1952"}],"wp:attachment":[{"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1949"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1949"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/pepsi.aip.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1949"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}