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Previous issue date: 2009-08-08 / Mira and R Coronae Borealis (R CrB) variable stars are evolved objects surrounded by circumstellar envelopes (CSE) composed of the ejected stellar material. We present a detailed high-spatial resolution morfological study of the CSE of three stars: IRC+10216, the closest and more studied Carbon-Rich Mira; o Ceti, the prototype of the Mira class; and RY Sagitarii (RY Sgr), the brightest R CrB variable of the south hemisphere. JHKL near-infrared adaptive optics images of IRC+10216 with high dynamic range and Vband images with high angular resolution and high depth, collected with the VLT/NACO
and VLT/FORS1 instruments, were analyzed. NACO images of o Ceti were also analyzed. Interferometric observations of RY Sgr collected with the VLTI/MIDI instrument allowed us to explore its CSE innermost regions (?20 40 mas). The CSE of IRC+10216 exhibit, in near-infrared, clumps with more complex relative displacements than proposed in previous studies. In V-band, the majority of the non-concentric shells, located in the
outer CSE layers, seem to be composed of thinner elongated shells. In a global view, the morphological connection between the shells and the bipolar core of the nebulae, located
in the outer layers, together with the clumps, located in the innermost regions, has a difficult interpretation. In the CSE of o Ceti, preliminar results would be indicating the presence of possible clumps. In the innermost regions (.110 UA) of the CSE of RY Sgr, two clouds were detected in different epochs, embedded in a variable gaussian envelope. Based on a rigorous verification, the first cloud was located at ?100 R? (or ?30 AU) from the centre, toward the east-north-east direction (modulo 180o) and the second one was almost at a perpendicular direction, having aproximately 2? the distance of the first cloud. This study introduces new constraints to the mass-loss history of these kind of variables and to the morphology of their innermost CSE regions / As vari?veis de tipo Mira e R Coronae Borealis (R CrB) est?o em est?gios evolutivos muito avan?ados e acumularam em seus entornos uma espessa camada do material estelar.
Apresentamos um estudo morfol?gico detalhado, em alta resolu??o espacial, sobre os ambientes em torno da estrela IRC+10216, a vari?vel de tipo Mira rica em Carbono mais
pr?oxima da Terra; o Ceti, o prot?tipo da classe Mira; e RY Sagitarii (RY Sgr), a vari?vel de tipo R CrB mais brilhante do hemisf?rio sul. Imagens de IRC+10216, nas bandas J,
H, K e L, com?tica adaptativa e alto intervalo din?mico, e imagens de alta profundidade no vis?vel, com alta resolu??o angular, coletadas com os instrumentos VLT/NACO e VLT/FORS1, foram analisadas, assim como observa??es NACO de o Ceti nas bandas I e J. Observa??es de RY Sgr, com o interfer?metro VLTI/MIDI, nos permitiram explorar as regi?es mais internas em torno da estrela central. O entorno de IRC+10216 apresenta, no infravermelho pr?ximo, concentra??es de mat?ria (grumos), cujos movimentos relativos
parecem mais complexos do que aqueles propostos em estudos anteriores. No vis?vel, a maioria das conchas n?o-conc?ntricas, localizadas nas camadas mais externas do envolt?rio, parece ser composta de outras conchas menos espessas. Globalmente, a conex?o morfol?gica das conchas e da bipolaridade da nebulosa das camadas mais externas, com os grumos das regi?es mais internas ? complexa e de dif?cil interpreta??o. No entorno de o Ceti, resultados preliminares estariam indicando a presen?a de poss?veis grumos. Nas regi?es mais internas de RY Sgr (.110 UA), duas nuvens de poeira foram detectadas em
?pocas diferentes, dentro de um envoltorio gaussiano variavel. Com base numa criteriosa verifica??o, a primeira estava a ?100 R? (ou ?30 UA) do centro, ao longo da dire??o
leste-nordeste (modulo 180o) e a segunda tinha quase o dobro da dist?ncia e dire??o aproximadamente perpendicular. Este estudo introduz novos v?nculos sobre a hist?ria da perda de massa das vari?veis estudadas e sobre a morfologia de suas regi?es mais internas
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/16557 |
| Date | 08 August 2009 |
| Creators | Le?o, Izan de Castro |
| Contributors | CPF:08896135400, http://lattes.cnpq.br/9151590034650501, L?pine, Jacques Raymond Daniel, CPF:02783096820, http://lattes.cnpq.br/9833768521859653, Pacheco, Eduardo Janot, CPF:07425864800, http://lattes.cnpq.br/0350534280247463, Nascimento J?nior, Jos? Dias do, CPF:85106038472, http://lattes.cnpq.br/5498036360601584, Martins, Bruno Leonardo Canto, CPF:96670193491, http://lattes.cnpq.br/2673267660389058, Pires, Nilza, CPF:38110326404, http://lattes.cnpq.br/2463198529477607, Medeiros, Jos? Renan de |
| Publisher | Universidade Federal do Rio Grande do Norte, Programa de P?s-Gradua??o em F?sica, UFRN, BR, F?sica da Mat?ria Condensada; Astrof?sica e Cosmologia; F?sica da Ionosfera |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Format | application/pdf |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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