| Texto completo | |
| Autor(es): |
Menezes, Fabian
;
Selhorst, Caius L.
;
Gimenez de Castro, Carlos Guillermo
;
Valio, Adriana
Número total de Autores: 4
|
| Tipo de documento: | Artigo Científico |
| Fonte: | Monthly Notices of the Royal Astronomical Society; v. 511, n. 1, p. 9-pg., 2022-02-03. |
| Resumo | |
Measurements of the radius and limb brightening of the Sun provide important information about the solar atmosphere structure and temperature. The solar radius increases as the observation at radio frequency decreases, indicating that each emission originates higher in the atmosphere. Thus, different layers of the solar atmosphere can be probed by observing at multiple wavelengths. In this work, we determined the average radius and limb brightening at 100, 212, 230, and 405 GHz, using data from the Solar Submillimeter Telescope and Atacama Large Millimeter/submillimeter Array's single-dish observations. For the first time, limb brightening values for frequencies of 212 and 405 GHz were estimated. At sub-THz frequencies, the observed limb brightening may affect the solar radius measurements. We use two different and well-known approaches to determine the radius: The half-power method and the inflection-point method. We investigate how the antenna beam size and the limb brightening level, LB, can affect the radius measurements using both methods. Our results showed that the inflection-point method is the least affected by these parameters, and should thus be used for solar radius estimates at radio wavelengths. The measured average radii are 968 +/- 3 arcsec (100 GHz), 963 +/- 3 arcsec (212 GHz), 963 +/- 2 arcsec (230 GHz), and 963 +/- 5 arcsec (405 GHz). Finally, we used forward modelling to estimate the ranges of LB of the solar disc resulting in 5-19 per cent (100 GHz), 2-12 per cent (212 GHz), 6-18 per cent (230 GHz), and 3-17 per cent (405 GHz). Both radius and limb brightening estimates agree with previous measurements reported in the literature. (AU) | |
| Processo FAPESP: | 13/10559-5 - Investigação de fenômenos de altas energias e plasmas astrofísicos: teoria, simulações numéricas, observações e desenvolvimento de instrumentação para o Cherenkov Telescope Array (CTA) |
| Beneficiário: | Elisabete Maria de Gouveia Dal Pino |
| Modalidade de apoio: | Auxílio à Pesquisa - Projetos Especiais |
| Processo FAPESP: | 13/24155-3 - Diagnóstico de explosões solares em inédito intervalo espectral, de micro-ondas até frequências THz: desafios para interpretação (FLAT) |
| Beneficiário: | Carlos Guillermo Giménez de Castro |
| Modalidade de apoio: | Auxílio à Pesquisa - Temático |
| Processo FAPESP: | 19/03301-8 - Observação e modelagem de regiões ativas solares e estelares em ondas rádio mm/sub-mm |
| Beneficiário: | Caius Lucius Selhorst |
| Modalidade de apoio: | Auxílio à Pesquisa - Regular |