Análise multitécnica dos parâmetros fotosféricos de Achernar : interferometria e espectroscopia

Abstract

Be stars are young objects with high rotational rates. This characteristic causes temperature, radius, and gravity to vary with latitude. Achernar is the most observed Be star to date, due to its proximity. As a result, there is an abundance of observational data for this object, which facilitates its analysis. In 2011, Achernar completely lost its disk. The analysis of observations from that period represents a unique opportunity to study its photospheric properties, avoiding contamination from the disk. Accordingly, the photospheric parameters of this star have been determined both through optical interferometry in 2014 and spectroscopic data in 2023. In this context, our goal is to employ a multi-technique approach, using interferometric and spectroscopic observations in the visible, to determine the photospheric parameters of Achernar. To study this star, we use a spectral synthesis model that accounts for the effects caused by rapid rotation. In this regime, properties such as temperature, gravity, and radius depend on the latitude across the stellar surface. We performed a combined fit of these observations, which had not been done until now. As a result of the simultaneous fitting of the spectrum and visibility, we obtained Tpole = 17017 ± 128 K, Req = 8.97 ± 0.13 R⊙, Ω/Ωk = 0.79 ± 0.04, and i = 60.3 ◦ ± 1.6 ◦ . The joint fit yielded smaller uncertainties and agreed with results found in the literature.