OBSERVATION OF THE CHROMOSPHERIC SUNSPOT AT MILLIMETER RANGE WITH THE NOBEYAMA 45 m TELESCOPE

Journal Article · Fri May 01 00:00:00 EDT 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/804/1/48· OSTI ID:22522475

Iwai, Kazumasa ^[1]; Shimojo, Masumi ^[2]

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1. Nobeyama Solar Radio Observatory, National Astronomical Observatory of Japan, Minamimaki, Nagano 384-1305 (Japan)
2. National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan)

The brightness temperature of the radio free–free emission at millimeter range is an effective tool for characterizing the vertical structure of the solar chromosphere. In this paper, we report on the first single-dish observation of a sunspot at 85 and 115 GHz with sufficient spatial resolution for resolving the sunspot umbra using the Nobeyama 45 m telescope. We used radio attenuation material, i.e., a solar filter, to prevent the saturation of the receivers. Considering the contamination from the plage by the side lobes, we found that the brightness temperature of the umbra should be lower than that of the quiet region. This result is inconsistent with the preexisting atmospheric models. We also found that the brightness temperature distribution at millimeter range strongly corresponds to the ultraviolet continuum emission at 1700 Å, especially at the quiet region.

• OSTI ID: 22522475
• Journal Information: Astrophysical Journal, Vol. 804, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ATTENUATION
BRIGHTNESS
CHROMOSPHERE
EMISSION SPECTRA
GHZ RANGE
PLAGES
SPATIAL RESOLUTION
SUN
SUNSPOTS
TELESCOPES
TEMPERATURE DISTRIBUTION
ULTRAVIOLET RADIATION