Solar limb brightening in submillimeter wavelengths

Journal Article · Sun Feb 01 04:00:00 EST 1976 · Astrophys. J., v. 203, no. 3, pp. 753-759

DOI:https://doi.org/10.1086/154136· OSTI ID:4028483

Lindsey, C; Hudson, H S

Differential two-beam scans of the Sun in submillimeter wavelengths (350 $mu$-1 millimeter), made with the UCSD-University of Minnesota 1.5 m telescope at Mount Lemmon, indicate limb brightening approaching 1 percent at $mu$=0.6. 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 our system (about 2' FWHM), 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 order 1500 km. High-resolution images in the wings of the K-line show granular structure of about this horizontal scale. (AIP)

• Research Organization: Department of Physics, University of California, San Diego
• Sponsoring Organization: USDOE
• NSA Number: NSA-33-030741
• OSTI ID: 4028483
• Journal Information: Astrophys. J., v. 203, no. 3, pp. 753-759, Journal Name: Astrophys. J., v. 203, no. 3, pp. 753-759; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

*SOLAR ATMOSPHERE-- PHOTOMETRY
640104* --Physics Research--Astrophysics & Cosmology--Solar Phenomena
BRIGHTNESS
CHROMOSPHERE
INFRARED RADIATION
N56400* --Physics (Astrophysics & Cosmology)--Solar Phenomena
SOLAR GRANULATION