Differential interferometric phases at high spectral resolution as a sensitive physical diagnostic of circumstellar disks

Author(s)

Faes, D. M. ^{[1, 2]} ; Carciofi, A. C. ^[1] ; Rivinius, Th. ^[3] ; Stefl, S. ^[4] ; Baade, D. ^[5] ; de Souza, A. Domiciano ^[2]

Affiliation

^[1] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfericas, BR-05508900 Sao Paulo - Brazil

^[2] Univ Nice Sophia Antipolis, CNRS, Lab JL Lagrange, Observ Cote Azur, UMR 7293, F-06108 Nice - France

^[3] European Org Astron Res Souhtern Hemisphere, Santiago 19 - Chile

^[4] ALMA, European Org Astron Res Southern Hemisphere, Santiago - Chile

^[5] European Org Astron Res Southern Hemisphere, D-85748 Garching - Germany

• Document type: Journal article
• Source: Astronomy & Astrophysics; v. 555, JUL 2013.
• Web of Science Citations: 2

Abstract

Context. The circumstellar disks ejected by many rapidly rotating B stars (so-called Be stars) offer the rare opportunity of studying the structure and dynamics of gaseous disks at high spectral as well as angular resolution. Aims. This paper explores a newly identified effect in spectro-interferometric phase that can be used for probing the inner regions of gaseous edge-on disks on a scale of a few stellar radii. Methods. The origin of this effect (dubbed central quasi-emission phase signature, CQE-PS) lies in the velocity-dependent line absorption of photospheric radiation by the circumstellar disk. At high spectral and marginal interferometric resolution, photocenter displacements between star and isovelocity regions in the Keplerian disk reveal themselves through small interferometric phase shifts. To investigate the diagnostic potential of this effect, a series of models are presented, based on detailed radiative transfer calculations in a viscous decretion disk. Results. Amplitude and detailed shape of the CQE-PS depend sensitively on disk density and size and on the radial distribution of the material with characteristic shapes in differential phase diagrams. In addition, useful lower limits to the angular size of the central stars can be derived even when the system is almost unresolved. Conclusions. The full power of this diagnostic tool can be expected if it can be applied to observations over a full life-cycle of a disk from first ejection through final dispersal, over a full cycle of disk oscillations, or over a full orbital period in a binary system. (AU)

• FAPESP's process: 09/54006-4 - A computer cluster for the Astronomy Department of the University of São Paulo Institute of Astronomy, Geophysics and Atmospheric Sciences and for the Cruzeiro do Sul University Astrophysics Center
• Grantee: Elisabete Maria de Gouveia Dal Pino
• Support Opportunities: Multi-user Equipment Program
• FAPESP's process: 10/19029-0 - 3D radiative transfer models: bridging theory and observations
• Grantee: Alex Cavaliéri Carciofi
• Support Opportunities: Regular Research Grants
• FAPESP's process: 12/04916-7 - An interferometric view on hot star disks
• Grantee: Daniel Moser Faes
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate