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Projeto Observacional para 2009A - OI2009A-042
Título: Polarimetric observations of Mira stars
Resumo: Evolved from typically solar mass stars, with a high mass loss rate of about 10−6 solar mass / year, Miras significantly enrich the interstellar medium, producing planetary nebulae after a rapid mass loss phase. From near infrared interferometric observations made by our group and other teams, these stars have revealed a complex photosphere/envelope which is the location of shock front propagation, molecular formation and destruction, SiO maser emission, and dust formation. The mode of dust formation and mass ejection is unknown. By using the polarimeter on the 0.6m telescope, we wish to understand the nature of the dust around Mira stars by observing the polarized light they radiate. Associated with future and already existing high angular resolution observations, these measurements will constrain the dust formation scenarios and consequently the mass loss mecanisms occuring in Mira stars.