Simultaneous SMM flat crystal spectrometer and Very Large Array observations of solar active regions

Journal Article · Sun Nov 01 04:00:00 EST 1987 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/165798· OSTI ID:5345738

Lang, K R; Willson, R F; Smith, K L; Strong, K T

High-resolution images of the quiescent emission from two solar active regions at 20 cm (VLA) and soft X-ray (SMM FCS) wavelengths are compared. There are regions where the X-ray coronal loops have been completely imaged at 20 cm wavelength. In other regions, the X-ray radiation was detected without detectable 20 cm radiation, and vice versa. The X-ray data were used to infer average electron temperatures of about 3-million K and average electron densities of about 2.5 x 10 to the 9th/cu cm for the X-ray emitting plasma in the two active regions. The thermal bremsstrahlung of the X-ray emitting plasma is optically thin at 20 cm wavelength. The 20 cm brightness temperatures were always less than T(e), which is consistent with optically thin bremsstrahlung. The low T(B) can be explained if a higher, cooler plasma covers the hotter X-ray emitting plasma. Thermal gyroresonance radiation must account for the intense 20 cm radiation near and above sunspots where no X-ray radiation is detected. 26 references.

• Research Organization: Tufts Univ., Medford, MA; Lockheed Research Labs., Palo Alto, CA
• OSTI ID: 5345738
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 322; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
COMPARATIVE EVALUATIONS
ELECTROMAGNETIC RADIATION
ELECTRON DENSITY
ELECTRON TEMPERATURE
IONIZING RADIATIONS
MEASURING INSTRUMENTS
PLASMA
RADIATIONS
RADIOWAVE RADIATION
SOFT X RADIATION
SOLAR ACTIVITY
SOLAR CORONA
SPECTROMETERS
STELLAR ATMOSPHERES
STELLAR CORONAE
X RADIATION