Solar limb brightening in submillimeter wavelengths

Abstract

view Abstract Citations (22) References (17) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Solar limb brightening in submillimeter wavelengths. Lindsey, C. ; Hudson, H. S. Abstract Differential two-beam scans of the sun in submillimeter wavelengths (350 microns to 1 millimeter) indicate limb brightening approaching 1 percent when the cosine of the angle from the normal equals 0.60. The observations also show considerable chromospheric structure, both in active and quiet regions, but with less relative amplitude than at millimeter and centimeter wavelengths. The limited angular resolution of the observing system, together with photometric errors due to fluctuating atmospheric transparency, make the brightness profile of the extreme limb uncertain. The observed degree of limb brightening is considerably less than that consistent with spherically symmetric model atmospheres based on continuum brightness-temperature measurements. The suppression of limb brightening suggests the existence of irregular granular structure with both horizontal and vertical characteristic sizes of the order of 1500 km. High-resolution images in the wings of the K-line show granular structure of about this horizontal scale. Publication: The Astrophysical Journal Pub Date: February 1976 DOI: 10.1086/154136 Bibcode: 1976ApJ...203..753L Keywords: Brightness Temperature; Chromosphere; Luminous Intensity; Solar Limb; Submillimeter Waves; Astronomical Models; Atmospheric Models; Infrared Radiation; Scale Height; Solar Atmosphere; Solar Granulation; Solar Physics full text sources ADS |