Reduced Coronal Emission Above Large Isolated Sunspots

B. I. Ryabov, Dale Gary, N. G. Peterova, K. Shibasaki, N. A. Topchilo

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

We analysed specific regions of reduced soft X-ray and microwave emission in five large isolated sunspots. The Nobeyama Radioheliograph 17 GHz observations reveal a local depression of microwave brightness in the peripheral area of the sunspots. The depression regions appear light (weak absorption) in the He 10830 Å line in areas with extended (open) field lines, as indicated by potential field source surface model (PFSS) extrapolations up to 1.5 R. The observed depressions of 3 – 8 % in ordinary mode at 17 GHz are interpreted as resulting from free–free emission when the plasma density is lower by 5 – 10 %. Our model estimates show that the decrease in density in both the coronal and the lower layers above the depression region accounts for the depression. These depression regions lend themselves well to marking the location of outward plasma motions.

Original languageEnglish (US)
Pages (from-to)21-35
Number of pages15
JournalSolar Physics
Volume290
Issue number1
DOIs
StatePublished - Jan 2015

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • Sun: corona, magnetic fields, radio emission

Fingerprint Dive into the research topics of 'Reduced Coronal Emission Above Large Isolated Sunspots'. Together they form a unique fingerprint.

Cite this