Analysis of Time-Distance Helioseismology for Detection of Emerging Active Regions

John T. Stefan, Alexander G. Kosovichev, Andrey M. Stejko

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


A time-distance helioseismic technique, similar to the one used by Ilonidis et al., is applied to two independent numerical models of subsurface sound-speed perturbations to determine the spatial resolution and accuracy of phase travel time shift measurements. The technique is also used to examine pre-emergence signatures of several active regions observed by the Michelson Doppler Imager and the Helioseismic Magnetic Imager. In the context of similar measurements of quiet-Sun regions, three of the five studied active regions show strong phase travel time shifts several hours prior to emergence. These results form the basis of a discussion of noise in the derived phase travel time maps and possible criteria to distinguish between true and false-positive detection of emerging flux.

Original languageEnglish (US)
Article number87
JournalAstrophysical Journal
Issue number2
StatePublished - Jun 1 2021

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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