@MastersThesis{Targon:2008:InCaMa,
author = "Targon, Cristiane Godoy",
title = "A influ{\^e}ncia do campo magn{\'e}tico interestelar na
forma{\c{c}}{\~a}o estelar associada a jatos {\'o}pticos",
school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
year = "2008",
address = "S{\~a}o Jos{\'e} dos Campos",
month = "2008-08-01",
keywords = "Campo magn{\'e}tico, forma{\c{c}}{\~a}o estelar, jatos, meio
interestelar, objetos herbig-haro, polarimetria, magnetic field,
star formation, jets, outflows, interstellar medium, herbig-haro
objects, polarimetry.",
abstract = "Em regi{\~o}es de forma{\c{c}}{\~a}o estelar de nossa
Gal{\'a}xia, encontramos os objetos Herbig-Haro, que resultam do
choque supers{\^o}nico de efluxos (outflows) originados em
estrelas jovens com o meio interestelar adjacente. O mecanismo que
se acredita ser respons{\'a}vel pela gera{\c{c}}{\~a}o dos
jatos (processo de acelera{\c{c}}{\~a}o
magneto-centr{\'{\i}}fuga) envolve a presen{\c{c}}a de um campo
magn{\'e}tico possivelmente remanescente do colapso gravitacional
que deu origem ao sistema disco-protoestrela. A
propaga{\c{c}}{\~a}o do jato no MI tamb{\'e}m pode ser
influenciada pelas caracter{\'{\i}}sticas do campo
magn{\'e}tico interestelar. Este trabalho {\'e} um estudo
observacional baseado em polarimetria {\'o}ptica CCD para a
procura de correla{\c{c}}{\~o}es entre as
caracter{\'{\i}}sticas do campo magn{\'e}tico do meio
interestelar nas vizinhan{\c{c}}as de objetos Herbig-Haro e as
propriedades desses objetos e de suas fontes centrais. Nossa
amostra {\'e} composta de 28 campos contendo 1 ou mais objetos
Herbig-Haro. Os resultados obtidos foram: o alinhamento entre a
geometria do objeto estelar jovem e o campo magn{\'e}tico depende
da idade do objeto, sendo que {\'e} observado alinhamento para
objetos de Classe 0 e I, mas n{\~a}o para objetos de Classe II e
III; jatos mais extensos tendem a ser perpendiculares ao campo
magn{\'e}tico do meio interestelar; a dispersao m{\'e}dia do
campo magn{\'e}tico do meio interestelar {\'e} maior para
objetos mais evolu{\'{\i}}dos, evidenciando que a
forma{\c{c}}{\~a}o estelar deve transferir momentum para o meio;
objetos de maior massa tendem a se localizar em locais com maior
dispersao do campo magn{\'e}tico, sendo prov{\'a}vel que essa
maior dispersao seja uma caracter´{\'y}stica da regiao anterior
{\`a} forma{\c{c}}{\~a}o estelar de alta massa,
influenciando-a; a polariza{\c{c}}{\~a}o m{\'e}dia dos campos
cresce com o avermelhamento em regi{\~o}es de baixa massa, mas
decresce em regi{\~o}es de alta massa. ABSTRACT: Herbig-Haro
objects result from the shocks of outflows from young stellar
objects with the surrounding interstellar medium of our Galaxy.
The mechanism believed to be responsible for the generation of
jets (magneto-centrifugal acceleration) involves the presence of a
magnetic field. It can be remnant from the interstellar magnetic
field in the parent molecular cloud from which the protostellar
object has been formed. Moreover, the interstellar magnetic field
may influence the outflow propagation. We present an optical
polarimetric study for the search of correlations between the
interstellar magnetic field and the characteristics of Herbig-Haro
objects and its central sources. Our sample is composed of 28
fields having one or more Herbig- Haro objects. We have found that
there is an alignment between the jet and the interstellar
magnetic field for Class 0 and Class I objects, but not for Class
II and Class III objects. The most extended jets in our sample
tend to be perpendicular to the magnetic field. The average
dispersion of the magnetic field in the studied regions is larger
for older objects, showing that the star formation process can
transfer momentum to the medium. From a point of view of the mass
of the central source, larger magnetic field dispersions are found
in regions containing high mass objects. We suggest that the
observed dispersion is a characteristic of the region prior to
star formation, playing a role on the collapse of this kind of
object. The mean interstellar polarization grows with extinction
in low mass star forming regions, but decreases in the high mass
ones. It could be explained by a smaller polarizing efficiency in
these regions.",
committee = "Boas, Jos{\'e} Williams dos Santos (presidente) and
Rodrigu{\^e}s, Cl{\'a}udia Vilega (orientadora) and Cerqueira,
Adriano Hoth and Franco, Gabriel Armando Pellegatti",
copyholder = "SID/SCD",
englishtitle = "The role of the interstellar magnetic field in the star formation
associated to optical jets",
language = "pt",
pages = "163",
ibi = "6qtX3pFwXQZGivnK2Y/UNqrs",
url = "http://urlib.net/ibi/6qtX3pFwXQZGivnK2Y/UNqrs",
targetfile = "publicacao.pdf",
urlaccessdate = "05 maio 2024"
}