NDLI: Determining Absorption, Emissivity Reduction, and Local Suppression Coefficients inside Sunspots

Content Provider	Springer Nature Link
Author	Ilonidis, Stathis Zhao, Junwei
Copyright Year	2010
Abstract	The power of solar acoustic waves is reduced inside sunspots mainly due to absorption, emissivity reduction, and local suppression. The coefficients of these power-reduction mechanisms can be determined by comparing time – distance cross-covariances obtained from sunspots and from the quiet Sun. By analyzing 47 active regions observed by SOHO/MDI without using signal filters, we have determined the coefficients of surface absorption, deep absorption, emissivity reduction, and local suppression. The dissipation in the quiet Sun is derived as well. All of the cross-covariances are width corrected to offset the effect of dispersion. We find that absorption is the dominant mechanism of the power deficit in sunspots for short travel distances, but gradually drops to zero at travel distances longer than about 6°. The absorption in sunspot interiors is also significant. The emissivity-reduction coefficient ranges from about 0.44 to 1.00 within the umbra and 0.29 to 0.72 in the sunspot, and accounts for only about 21.5% of the umbra’s and 16.5% of the sunspot’s total power reduction. Local suppression is nearly constant as a function of travel distance with values of 0.80 and 0.665 for umbrae and whole sunspots respectively, and is the major cause of the power deficit at large travel distances.
Starting Page	377
Ending Page	388
Page Count	12
File Format	PDF
ISSN	00380938
Journal	Solar Physics
Volume Number	268
Issue Number	2
e-ISSN	1573093X
Language	English
Publisher	Springer Netherlands
Publisher Date	2010-08-28
Publisher Place	Dordrecht
Access Restriction	One Nation One Subscription (ONOS)
Subject Keyword	Helioseismology Sunspots Absorption Emissivity reduction Local suppression Acoustic waves Extraterrestrial Physics, Space Sciences Meteorology/Climatology Astrophysics and Astroparticles
Content Type	Text
Resource Type	Article
Subject	Astronomy and Astrophysics Space and Planetary Science

Sl.	Authority	Responsibilities	Communication Details
1	Ministry of Education (GoI), Department of Higher Education	Sanctioning Authority	https://www.education.gov.in/ict-initiatives
2	Indian Institute of Technology Kharagpur	Host Institute of the Project: The host institute of the project is responsible for providing infrastructure support and hosting the project	https://www.iitkgp.ac.in
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
5	Website/Portal (Helpdesk)	Queries regarding NDLI and its services	support@ndl.gov.in
6	Contents and Copyright Issues	Queries related to content curation and copyright issues	content@ndl.gov.in
7	National Digital Library of India Club (NDLI Club)	Queries related to NDLI Club formation, support, user awareness program, seminar/symposium, collaboration, social media, promotion, and outreach	clubsupport@ndl.gov.in
8	Digital Preservation Centre (DPC)	Assistance with digitizing and archiving copyright-free printed books	dpc@ndl.gov.in
9	IDR Setup or Support	Queries related to establishment and support of Institutional Digital Repository (IDR) and IDR workshops	idr@ndl.gov.in

Local Helioseismology of Sunspots: Current Status and Perspectives

Determining Absorption, Emissivity Reduction, and Local Suppression Coefficients inside Sunspots

Determining Absorption, Emissivity Reduction, and Local Suppression Coefficients inside Sunspots

Constructing Semi-Empirical Sunspot Models for Helioseismology

Acoustic Power Absorption and its Relation to Vector Magnetic Field of a Sunspot

Toward Waveform Heliotomography: Observing Interactions of Helioseismic Waves with a Sunspot

Phase Jumps in Local Helioseismology

Multichannel Three-Dimensional SOLA Inversion for Local Helioseismology

Corrections to the Magnitude of Cross-Correlation Functions for Dispersion of Solar Acoustic Waves

Determining Absorption, Emissivity Reduction, and Local Suppression Coefficients inside Sunspots

Similar Documents

Local Helioseismology of Sunspots: Current Status and Perspectives

Determining Absorption, Emissivity Reduction, and Local Suppression Coefficients inside Sunspots

Determining Absorption, Emissivity Reduction, and Local Suppression Coefficients inside Sunspots

Constructing Semi-Empirical Sunspot Models for Helioseismology

Acoustic Power Absorption and its Relation to Vector Magnetic Field of a Sunspot

Toward Waveform Heliotomography: Observing Interactions of Helioseismic Waves with a Sunspot

Phase Jumps in Local Helioseismology

Multichannel Three-Dimensional SOLA Inversion for Local Helioseismology

Corrections to the Magnitude of Cross-Correlation Functions for Dispersion of Solar Acoustic Waves

Determining Absorption, Emissivity Reduction, and Local Suppression Coefficients inside Sunspots