Searching for new molecular tracers to outline the disk-like structures of B[e] supergiants

TORRES, ANDREA; KRAUS, MICHAELA; VALLVERDÚ, RODOLFO; CIDALE, LYDIA

Tõravere, Tartu

Workshop; Massie Stars in Transition Phases; 2017

Tartu Observatory

B[e] supergiants display circumstellar disk-like structures that can be outlined by different atomic and molecular tracers.The innermost regions are usually traced by permitted and forbidden transitions of neutral and singly ionized metal lines which reveal the dynamics and physical structure of these complex regions. The outermost regions are characterized by emission from warm dust, and in between these two regions the conditions are optimal for the formation of various molecules. Up to now, all information on the molecular disk properties was derived using the emission bands of CO, and only in a few cases SiO molecular band emission was detected. Our goal is to vastly improve the current knowledge of the chemical composition of B[e] supergiant stars´ disks. We will model the expected emission from a diversity of diatomic molecules, such as VO, CaO and CS, which are expected to form in significant amounts. These computed spectra will then be confronted with observations. The detection of new molecules is not an easy task since telluric absorption veils the stellar spectrum. Hence detailed and accurate molecular models are necessary to unambiguously identify the presumably very weak molecular emission coming from the circumstellar disks.