Authors: S Kholikov
Publish Date: 2013/06/05
Volume: 287, Issue: 1-2, Pages: 229-237
Abstract
Using SOHO/MDI and GONG observations we present time–distance deepfocusing measurements to examine the deeper layers of the solar convective zone The constructed traveltime maps show 10 – 15 second perturbations at depths of 40 – 75 Mm around active region locations before their emergence to the solar surface The majority of the active regions used in this study were the same as those used in the recent work published by Ilonidis Zhao and Kosovichev Science 333 993 2011 In order to confirm the capability of time–distance measurements to detect emerging active regions we used a technique similar to their time–distance scheme Our measurements only in some cases show a similar traveltime anomaly Additionally we have shown that the technique utilized in our study can provide more spatial details of the emerging flux configurationsThis work utilized data obtained by the Global Oscillation Network Group GONG program managed by the National Solar Observatory which is operated by AURA Inc under a cooperative agreement with the National Science Foundation The data were acquired by instruments operated by the Big Bear Solar Observatory High Altitude Observatory Learmonth Solar Observatory Udaipur Solar Observatory Instituto de Astrofísica de Canarias and Cerro Tololo Interamerican Observatory SOHO is a mission of international cooperation between NASA and ESA Many thanks to A Kosovichev for suggestions and useful comments which helped to improve the readability of the manuscript
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