Viscous decretion disks: theory and observations

Abstract

Optical and infrared interferometry has allowed for great strides in many areas of astrophysics, in particular in stellar astrophysics, as it enables angularly resolved observations of nearby stars, providing unprecedented details about their photospheres and circumstellar environment. Pari passu with the observational advancements, there have been also quite significant advancements in numerical simulations.The BeACoN group, coordinated by the applicant since 2009, uses the HDUST code to bridge the most recent observations of Be stars, including state-of-de-art interferometric observations, and the theoretical models of Be stars and their circumstellar disks. BeACoN currently has 2 post-docs, 6 PhD students, 1 master student and 4 undergrad students, and has produced 26 refereed publications since 2009.Recently, major advances were implemented in HDUST that is now capable of handling He and other elements (in addition to H and dust) in the NLTE regime and in three-dimensional configurations. This new version of HDUST offers new and quite exciting scientific opportunities that will be actively pursued in the coming months/years by the applicant and his collaborators.Our main initial goals are i) to study how the inclusion of He will affect the thermal structure of gaseous disks, and ii) how the He I and II lines can be used to probe and constrain the properties of the inner parts of these disks.Besides these two new objectives we will carry on activities already started and that will mature in the next couple of years.The BeACoN group (as well as many others from the Astronomy Department of IAG/USP) uses heavily the computer clusters of the Laboratório de Astroinformática (LAi), which was built by the applicant between 2009 and 2012. The equipment requested in this project will address an important current limitation of LAi, namely the critical lack of disk space of the main storage device. It is important to stress that the requested investment will also benefit the entire Lai community, which 184 users from several institutions from Brazil and abroad. (AU)