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Title: TEMPORAL STABILITY OF SUNSPOT UMBRAL INTENSITIES: 1986-2012

Abstract

We examine the relative intensity of sunspot umbrae during the period from 1986 to 2012 using photometric images from the San Fernando Observatory. We confirm the presence of a relationship between the mean umbral core intensity and the mean sunspot area, as found in previous studies, and do not find a notable change in this relationship between cycles 22 and 23. We looked for a possible time variation in the sunspot umbral contrast during the 27 yr covering cycles 22, 23, and the rise of cycle 24, and we did not find a significant change. These findings do not indicate that sunspots have become less dark during cycles 23 and 24.

Authors:
 [1]; ;
  1. High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80301 (United States)
Publication Date:
OSTI Identifier:
22118707
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal Letters
Additional Journal Information:
Journal Volume: 771; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 2041-8205
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTRONOMY; ASTROPHYSICS; IMAGES; MAGNETISM; PHOTOMETRY; PHOTOSPHERE; SOLAR CYCLE; STABILITY; SUN; SUNSPOTS; SURFACES; TIME DEPENDENCE; VARIATIONS

Citation Formats

De Toma, G., Chapman, G. A., Cookson, A. M., and Preminger, D., E-mail: detoma@ucar.edu. TEMPORAL STABILITY OF SUNSPOT UMBRAL INTENSITIES: 1986-2012. United States: N. p., 2013. Web. doi:10.1088/2041-8205/771/2/L22.
De Toma, G., Chapman, G. A., Cookson, A. M., & Preminger, D., E-mail: detoma@ucar.edu. TEMPORAL STABILITY OF SUNSPOT UMBRAL INTENSITIES: 1986-2012. United States. https://doi.org/10.1088/2041-8205/771/2/L22
De Toma, G., Chapman, G. A., Cookson, A. M., and Preminger, D., E-mail: detoma@ucar.edu. 2013. "TEMPORAL STABILITY OF SUNSPOT UMBRAL INTENSITIES: 1986-2012". United States. https://doi.org/10.1088/2041-8205/771/2/L22.
@article{osti_22118707,
title = {TEMPORAL STABILITY OF SUNSPOT UMBRAL INTENSITIES: 1986-2012},
author = {De Toma, G. and Chapman, G. A. and Cookson, A. M. and Preminger, D., E-mail: detoma@ucar.edu},
abstractNote = {We examine the relative intensity of sunspot umbrae during the period from 1986 to 2012 using photometric images from the San Fernando Observatory. We confirm the presence of a relationship between the mean umbral core intensity and the mean sunspot area, as found in previous studies, and do not find a notable change in this relationship between cycles 22 and 23. We looked for a possible time variation in the sunspot umbral contrast during the 27 yr covering cycles 22, 23, and the rise of cycle 24, and we did not find a significant change. These findings do not indicate that sunspots have become less dark during cycles 23 and 24.},
doi = {10.1088/2041-8205/771/2/L22},
url = {https://www.osti.gov/biblio/22118707}, journal = {Astrophysical Journal Letters},
issn = {2041-8205},
number = 2,
volume = 771,
place = {United States},
year = {Wed Jul 10 00:00:00 EDT 2013},
month = {Wed Jul 10 00:00:00 EDT 2013}
}