Spectral signature of solar active region in millimetre and submillimetre wavelengths

Author(s)

Valle Silva, J. F. ^[1] ; Gimenez de Castro, C. G. ^{[1, 2]} ; Selhorst, C. L. ^[3] ; Raulin, J-P ^[1] ; Valio, A. ^[1]

Affiliation

^[1] Univ Presbiteriana Mackenzie, CRAAM, BR-01302907 Sao Paulo, SP - Brazil

^[2] Consejo Nacl Invest Cient & Tecn, Inst Astron & Fis Espacio, C1033AAJ, Buenos Aires, DF - Argentina

^[3] Univ Cruzeiro Sul, Univ Cidade Sao Paulo, Nucleo Astrofis, NAT, Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: Monthly Notices of the Royal Astronomical Society; v. 500, n. 2, p. 1964-1969, JAN 2021.
• Web of Science Citations: 0

Abstract

Active regions were observed with different instruments covering the spectral band from 17 to 405 GHz. The observations were made with the Nobeyama Radioheliograph (17 GHz), the Atacama Large Millimetre Array (107 and 238 GHz), and the Solar Submillimeter Telescope (212 and 405 GHz). A procedure was developed that allows the comparison between observations taken with telescopes of different operational characteristics and mainly of different spatial resolution. The brightness temperature and density flux spectra of several active regions corresponding to a different phase of its lifetime were obtained. The flux density invariably increases in all cases from 107 to 405 GHz and the mean spectral index is similar to 2 showing that the dominant emission mechanism at submillimeter frequencies is still thermal. We show that Solar Submillimeter Telescope (SST) and Atacama Large Millimeter/submillimeter Array (ALMA) observations are compatible within the uncertainties, a result of great interest for future joint observations. (AU)

• FAPESP's process: 13/24155-3 - Solar flare diagnostic in an unprecedented frequency range from microwaves to THz frequencies: challenges for interpretation (flat)
• Grantee: Carlos Guillermo Giménez de Castro
• Support Opportunities: Research Projects - Thematic Grants