Helioseismic signature of chromospheric downflows in acoustic travel-time measurements from Hinode

Kaori Nagashima, Takashi Sekii, Alexander G. Kosovichev, Junwei Zhao, Theodore D. Tarbell

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

We report on a signature of chromospheric downflows in two emerging flux regions detected by time-distance helioseismology analysis. We use both chromospheric intensity oscillation data in the Ca II H line and photospheric Dopplergrams in the Fe I 557.6 nm line obtained by Hinode/SOT for our analyses. By cross-correlating the Ca II oscillation signals, we have detected a travel-time anomaly in the plage regions; outward travel times are shorter than inward travel times by 0.5-1 minute. However, such an anomaly is absent in the Fe I data. These results can be interpreted as evidence of downflows in the lower chromosphere. The downflow speed is estimated to be below 10 km s -1. This result demonstrates a new possibility of studying chromospheric flows by time-distance analysis.

Original languageEnglish (US)
Pages (from-to)L115-L119
JournalAstrophysical Journal
Volume694
Issue number2
DOIs
StatePublished - 2009
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • Sun: chromosphere
  • Sun: faculae, plages
  • Sun: helioseismology

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