TEMPORAL STABILITY OF SUNSPOT UMBRAL INTENSITIES: 1986-2012

Journal Article · Wed Jul 10 00:00:00 EDT 2013 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/771/2/L22· OSTI ID:22118707

De Toma, G. ^[1]; Chapman, G. A.; Cookson, A. M.

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1. High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80301 (United States)

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.

• OSTI ID: 22118707
• Journal Information: Astrophysical Journal Letters, Vol. 771, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ASTRONOMY
ASTROPHYSICS
IMAGES
MAGNETISM
PHOTOMETRY
PHOTOSPHERE
SOLAR CYCLE
STABILITY
SUN
SUNSPOTS
SURFACES
TIME DEPENDENCE
VARIATIONS