NDLI: Reduced Coronal Emission Above Large Isolated Sunspots

Content Provider	Springer Nature Link
Author	Ryabov, B. I. Gary, D. E. Peterova, N. G. Shibasaki, K. Topchilo, N. A.
Copyright Year	2014
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.
Starting Page	21
Ending Page	35
Page Count	15
File Format	PDF
ISSN	00380938
Journal	Solar Physics
Volume Number	290
Issue Number	1
e-ISSN	1573093X
Language	English
Publisher	Springer Netherlands
Publisher Date	2014-12-02
Publisher Place	Dordrecht
Access Restriction	One Nation One Subscription (ONOS)
Subject Keyword	Sun: corona, magnetic fields, radio emission Astrophysics and Astroparticles Atmospheric Sciences Extraterrestrial Physics, Space Sciences
Content Type	Text
Resource Type	Article
Subject	Astronomy and Astrophysics Space and Planetary Science

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1	Ministry of Education (GoI), Department of Higher Education	Sanctioning Authority	https://www.education.gov.in/ict-initiatives
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3	National Digital Library of India Office, Indian Institute of Technology Kharagpur	The administrative and infrastructural headquarters of the project	Dr. B. Sutradhar bsutra@ndl.gov.in
4	Project PI / Joint PI	Principal Investigator and Joint Principal Investigators of the project	Dr. B. Sutradhar bsutra@ndl.gov.in Prof. Saswat Chakrabarti will be added soon
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