Dynamical evolution of viscous disks around be stars. II : polarimetry
| Full text | |
| Author(s): |
Vieira, R. G.
;
Carciofi, A. C.
;
Bjorkman, J. E.
;
Rivinius, Th.
;
Baade, D.
;
Rimulo, L. R.
Total Authors: 6
|
| Document type: | Journal article |
| Source: | Monthly Notices of the Royal Astronomical Society; v. 464, n. 3, p. 3071-3089, JAN 2017. |
| Web of Science Citations: | 19 |
| Abstract | |
We apply the viscous decretion disc (VDD) model to interpret the infrared disc continuum emission of 80 Be stars observed in different epochs. In this way, we determined 169 specific disc structures, namely their density scale, rho 0, and exponent, n. We found that the n values range mainly between 1.5 and 3.5, and rho 0 varies between 10(-12) and 10(-10) g cm(-3), with a peak close to the lower value. Our large sample also allowed us to firmly establish that the discs around early-type stars are denser than in late-type stars. Additionally, we estimated the disc mass decretion rates and found that they range between 10(-12) and 10(-9)M(circle dot)yr(-1). These values are compatible with recent stellar evolution models of fast-rotating stars. One of the main findings of this work is a correlation between the rho 0 and n values. In order to find out whether these relations can be traced back to the evolution of discs or have some other origin, we used the VDD model to calculate temporal sequences under different assumptions for the time profile of the disc mass injection. The results support the hypothesis that the observed distribution of disc properties is due to a common evolutionary path. In particular, our results suggest that the time-scale for disc growth, during which the disc is being actively fed by mass injection episodes, is shorter than the time-scale for disc dissipation, when the disc is no longer fed by the star and dissipates as a result of the viscous diffusion of the disc material. (AU) | |
| FAPESP's process: | 15/17967-7 - Viscous decretion disks: theory and observations |
| Grantee: | Alex Cavaliéri Carciofi |
| Support type: | Regular Research Grants |
| 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 type: | Multi-user Equipment Program |
| FAPESP's process: | 12/20364-4 - Beyond dust survival: the inner regions of protoplanetary disks |
| Grantee: | Rodrigo Georgetti Vieira |
| Support type: | Scholarships in Brazil - Post-Doctorate |