Modeling brightness temperature of sunspots using ALMA single‐dish observations
Loading...
Author (Corporation)
Publication date
2026
Type of student thesis
Course of study
Collections
Type
01A - Journal article
Editors
Editor (Corporation)
Supervisor
Parent work
Astronomische Nachrichten
Special issue
DOI of the original publication
Link
Related research data
Series
Series number
Volume
347
Issue / Number
4
Pages / Duration
Patent number
Publisher / Publishing institution
Wiley
Place of publication / Event location
Edition
Version
Programming language
Assignee
Practice partner / Client
Abstract
We model sunspot brightness temperature in the wavelength range 0.3–10 mm using the Atacama Large Millimeter/submillimeter Array (ALMA) single‐dish measurements together with other instruments. Our modeling idea starts from an existing model, the 1D semi‐empirical Avrett‐Tian‐Landi‐Curdt‐Wülser (ATLCW) model for sunspots. The original model is then modified in density and temperature with a constant factor over all heights. A least‐square fit in both density and temperature to the observed values yields an improved model for sunspot brightness temperature. Observations show that sunspots are darker than QS at wavelengths below 2 mm and brighter beyond, while fitting of the ATLCW sunspot model imply that sunspots should be darker than QS over the entire ALMA range. The best‐fitted sunspot brightness temperature profiles resulted in 3.6–4.0 times lower sunspot density compared to the original sunspot ATLCW model, or 1.4–1.8 times higher density compared to QS. The temperature came out around 1.2 times higher than the original ATLCW predictions for sunspots, or 1.2 times lower than QS temperature. Even with improved density and temperature parameters, the remaining discrepancy between the best‐fitted models and observations indicated that additional improvements are needed in the ATLCW model and modeling assumptions.
Keywords
Subject (DDC)
Event
Exhibition start date
Exhibition end date
Conference start date
Conference end date
Date of the last check
ISBN
ISSN
0004-6337
1521-3994
1521-3994
Language
English
Created during FHNW affiliation
Yes
Strategic action fields FHNW
Publication status
Published
Review
peer-reviewed
Open access category
Closed
Citation
Matković, F., Brajša, R., Benz, A. O., Ludwig, H.-G., Selhorst, C. L., Skokić, I., Sudar, D., & Hanslmeier, A. (2026). Modeling brightness temperature of sunspots using ALMA single‐dish observations. Astronomische Nachrichten, 347(4). https://doi.org/10.1002/asna.70089