Artículo
Diffuse component spectra of solar active regions at submillimeter wavelengths
Silva, Adriana V. R.; Laganá, Tatiana F.; Gimenez de Castro, C. Guillermo; Kaufmann, Pierre; Costa, Joaquim E. R.; Levato, Orlando Hugo
; Rovira, Marta Graciela
Fecha de publicación:
12/2005
Editorial:
Springer
Revista:
Solar Physics
ISSN:
0038-0938
Idioma:
Inglés
Tipo de recurso:
Artículo publicado
Clasificación temática:
Resumen
Solar maps at 212 and 405 GHz obtained by the Solar Submillimetric Telescope (SST) show regions of enhanced brightness temperature, which coincide with the location of active regions. A statistical study of the radio emission from these active regions was performed for the first time at such high frequencies during 23 days on June and July 2002, when the atmospheric opacity was low. The brightest regions on the maps were chosen for this study, where the brightness excess observed varies from 3 to 20% above quiet Sun levels (i.e., 200–1000 K) at both wavelengths. Sizes of the regions of enhanced emission calculated at half the maximum value were estimated to be between 2′ and 7′. These sizes agree with observed sizes of active regions at other wavelengths such as Hα and ultraviolet. An important result is that the flux density spectra of all sources increase toward submillimeter frequencies, yielding flux density spectral index with an average value of 2.0. The flux density of the active region sources were complemented with that from maps at 17 and 34 GHz from the Nobeyama Radio Heliograph. The resulting spectra at all four frequencies were fit considering the flux density to be due to thermal bremsstrahlung from the active region. In the calculations, the source radius was assumed to be the mean of the measured values at 212 and 405 K. The effective temperatures of the radio emitting source, assumed homogeneous, obtained from this fit were 0.6–2.9 × 104 K, for source diameters of 2′–7′.
Palabras clave:
Solar Physics
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Articulos(IAFE)
Articulos de INST.DE ASTRONOMIA Y FISICA DEL ESPACIO(I)
Articulos de INST.DE ASTRONOMIA Y FISICA DEL ESPACIO(I)
Articulos(ICATE)
Articulos de INST.D/CS ASTRONOMICAS D/LA TIERRA Y DEL ESPACIO
Articulos de INST.D/CS ASTRONOMICAS D/LA TIERRA Y DEL ESPACIO
Citación
Silva, Adriana V. R.; Laganá, Tatiana F.; Gimenez de Castro, C. Guillermo; Kaufmann, Pierre; Costa, Joaquim E. R.; et al.; Diffuse component spectra of solar active regions at submillimeter wavelengths; Springer; Solar Physics; 227; 2; 12-2005; 265-281
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