@PhDThesis{Trevisan:1991:EsMuEx,
author = "Trevisan, Rute Helena",
title = "Estudos multiespectrais das explos{\~o}es solares associadas com
a fase impulsiva do flare",
school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
year = "1991",
address = "S{\~a}o Jos{\'e} dos Campos",
month = "1991-03-26",
keywords = "explos{\~o}es solares, ondas de r{\'a}dio, estudos
multiespectrais, solar explosions, radio waves, multispectral
studies.",
abstract = "Existem poucos estudos de observa{\c{c}}{\~o}es multiespectrais
com alta sensibilidade e resolu{\c{c}}{\~a}o em
tempo/frequ{\^e}ncia/energia. A import{\^a}ncia de tais
investiga{\c{c}}{\~o}es e que estes estudos nos permitem
observar o desenvolvimento do fen{\^o}meno associado
simultaneamente em varias alturas na atmosfera solar, e do qual
podemos obter informa{\c{c}}{\~o}es sobre a regi{\~a}o de
acelera{\c{c}}{\~a}o, propaga{\c{c}}{\~a}o de
part{\'{\i}}culas aceleradas na dire{\c{c}}{\~a}o da
fotosfera, e coroa e emiss{\~a}o causada por essas
part{\'{\i}}culas. Essas informa{\c{c}}{\~o}es podem nos
explicar melhor os processos de libera{\c{c}}{\~a}o de energia
no flare solar. Nos investigamos aqui, explos{\~o}es solares em
H- , raios-X, microondas, ondas decim{\'e}tricas e m{\'e}tricas,
na fase impulsiva do flare. Os estudos simult{\^a}neos das
explos{\~o}es solares de ondas milim{\'e}tricas e m{\'e}tricas
e suas estruturas-finas, tem sugerido que as part{\'{\i}}culas
s{\~a}o aceleradas para energias de at{\'e} 200 KeV;
estruturas-finas s{\~a}o geradas por part{\'{\i}}culas
aceleradas em processos secund{\'a}rios. Al{\'e}m disso
aquecimento e acelera{\c{c}}{\~a}o ocorrem simultaneamente no
flare solar. As observa{\c{c}}{\~o}es foram realizadas com a
antena de 13,7 m de di{\^a}metro de Atibaia, pela primeira vez
operando na faixa de decim{\'e}tricas (1663 MHz) com alta
sensibilidade e resolu{\c{c}}{\~a}o temporal. N{\'o}s
observamos pela primeira vez: i) blips acima de 1000 MHz, ii)
explos{\~o}es homologas-like em microondas e spikes de baixa
intensidade de fluxo. As investiga{\c{c}}{\~o}es mostraram que
blips s{\~a}o variantes das explos{\~o}es tipo III e s{\~a}o
geradas pela intera{\c{c}}{\~a}o do feixe de el{\'e}tros com
plasma, no segundo harm{\^o}nico. Spikes s{\~a}o gerados por
ECM, e, assumindo-se a instabilidade MHD as dimens{\~o}es de
fonte s{\~a}o estimadas em 50 Km. Os flares hom{\'o}logos-like
de per{\'{\i}}odo longos de repeti{\c{c}}{\~a}o (~ 40 min),
s{\~a}o explicados pela oscila{\c{c}}{\~a}o de
proemin{\^e}ncia, como tamb{\'e}m os hom{\'o}logos de
per{\'{\i}}odos curtos de repeti{\c{c}}{\~a}o (~ 10s).
Investiga{\c{c}}{\~o}es mais detalhadas dessas explos{\~o}es
apresentadas aqui, leva-nos finalmente a sugerir que a energia do
flare solar e liberada em pequenos volumes e escalas de tempo 1.e.
ocorre a fragmenta{\c{c}}{\~a}o de energia quando o fluxo
emergente entra em contato com o campo magn{\'e}tico existente.
ABSTRACTS: There are a few studies of multispectral observations
with high sensitivity and time/frequency/energy resolution.
Importance of such investigations is that these studies allow to
see time development of the associated phenomenon simultaneously
at various heights in the solar atmosphere, from which one can
gather information about the region of acceleration, propagation
of accelerated particles towards and away from the photosphere and
emission caused by these particles, which can throw light on the
processes of liberation of energy in solar fiares. Here,we have
investigated solar bursts occurring in H-a, hard X-rays,
microwave, decimeter and meter wave in impulsive phase of the
solar flare. Simultaneous studies of millimeter-wave and
meter-wave bursts and its fine structure have suggested that
particles are accelerated up to energies ~200 keV , and
\λ-meter-wave fine structure 1 generated by the particles
accelerated in a secondary process. Moreover heating and
acceleration occurs simultaneously in the solar flare. Using 13.7
m Atibaia antena decimetric, 1663 MHz, observations have been
carried out for the first time with high sensitivity and high time
resolution. We observed for the first time low flux level blips
above 1000 MHz , spikes and microwave homologous like bursts.
Investigations showed that blips are variants of type III bursts
and are generated by beam plasma interaction at second harmonic.
Spikes are assumed to be generated by E.C.M. and, assuming M. H.
D. instability, estimated dimensions of radio sources are of the
order of 50 km. Oscillations of prominences offer better
explanation for long period , 40 minute, homologous bursts and can
explain small periodicities of the order of 10 seconds. More
detailed investigations of the bursts presented here, finally lead
us to suggest that the flare energy is liberated in a small volume
over small time scales i.e. there is fragmentation of energy when
emerging magnetic flux comes in contact with the existing magnetic
field.",
committee = "Kane, Rajaram Purushottam (presidente) and Sawant, Hanumant
Shankar (orientador) and Landaberry, Sayd Jos{\'e} Codina and
L{\'e}pine, Jacques Raymond Daniel and Gonzalez-Alarcon, Walter
Dem{\'e}trio and Scalise J{\'u}nior, Eug{\^e}nio",
copyholder = "SID/SCD",
englishtitle = "Multiespectral studies of the solar bursts associated with
impulsive phase.",
language = "pt",
pages = "204",
ibi = "6qtX3pFwXQZ3P8SECKy/DFbxQ",
url = "http://urlib.net/ibi/6qtX3pFwXQZ3P8SECKy/DFbxQ",
targetfile = "Rute Helena Trevisan 06_02_19.pdf",
urlaccessdate = "20 abr. 2024"
}