Simultaneous solar maximum mission (SMM) and very large array (VLA) observations of solar active regions. Final technical report, 1 February 1985-31 January 1991

Technical Report · Fri Feb 01 04:00:00 EST 1991

OSTI ID:5913127

Willson, R F

Very Large Array observations at 20 cm wavelength can detect the hot coronal plasma previously observed at soft x ray wavelengths. Thermal cyclotron line emission was detected at the apex of coronal loops where the magnetic field strength is relatively constant. Detailed comparison of simultaneous Solar Maximum Mission (SMM) Satellite and VLA data indicate that physical parameters such as electron temperature, electron density, and magnetic field strength can be obtained, but that some coronal loops remain invisible in either spectral domain. The unprecedent spatial resolution of the VLA at 20 cm wavelength showed that the precursor, impulsive, and post-flare components of solar bursts originate in nearby, but separate loops or systems of loops.. In some cases preburst heating and magnetic changes are observed from loops tens of minutes prior to the impulsive phase. Comparisons with soft x ray images and spectra and with hard x ray data specify the magnetic field strength and emission mechanism of flaring coronal loops. At the longer 91 cm wavelength, the VLA detected extensive emission interpreted as a hot 10(exp 5) K interface between cool, dense H alpha filaments and the surrounding hotter, rarefield corona. Observations at 91 cm also provide evidence for time-correlated bursts in active regions on opposite sides of the solar equator; they are attributed to flare triggering by relativistic particles that move along large-scale, otherwise-invisible, magnetic conduits that link active regions in opposite hemispheres of the Sun.

• Research Organization: Tufts Univ., Medford, MA (USA)
• OSTI ID: 5913127
• Report Number(s): N-91-18916; NASA-CR--187907; NAS--1.26:187907; CNN: NAG5-501
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
BREMSSTRAHLUNG
CYCLOTRON RADIATION
DATA
DOCUMENT TYPES
ELECTROMAGNETIC RADIATION
ELECTRON DENSITY
EXPERIMENTAL DATA
INFORMATION
MAGNETIC FLUX
NUMERICAL DATA
PLASMA
PROGRESS REPORT
RADIATIONS
RADIOWAVE RADIATION
RESOLUTION
SOLAR ACTIVITY
SOLAR CORONA
SOLAR FLARES
SOLAR RADIO BURSTS
SPATIAL RESOLUTION
SPECTRA
STELLAR ATMOSPHERES
STELLAR CORONAE
THERMAL RADIATION
X-RAY SPECTRA