Effects of dust on light-curves of ɛ Aurigae-type stars
Abstract
Context.ɛ Auriga is one of the most mysterious objects in the sky. Previous modeling of its light-curve assumed a dark, inclined, non-transparent or semi-transparent dusty disk with a central hole. The hole was necessary to explain the light-curve with a sharp mid-eclipse brightening.
Aims: The aim of the present paper is to study the effects of dust on the light-curves of eclipsing binary stars and to develop an alternative physical model for ɛ Aur-type objects that is based on the optical properties of dust grains.
Methods: The code Shellspec was modified to calculate the light-curves and spectra of these objects. The code solves the radiative transfer along the line of sight in interacting binaries. Dust and angle-dependent Mie scattering were included in the code for this purpose.
Results: Our model of ɛ Aur consists of two geometrically thick flared disks: an internal optically thick disk and an external optically thin disk, which absorbs and scatters radiation. Disks are in the orbital plane and are almost edge-on. We argue that there is no need for a highly inclined disk with a hole to explain the current eclipse of ɛ Aur even if there is a possible shallow mid-eclipse brightening. We demonstrate that phase-dependent light scattering and the optical properties of the dust can have a significant effect on the light-curves of these stars and can even produce a mid-eclipse brightening. This is a natural consequence of the strong forward scattering. We also demonstrate that shallow mid-eclipse brightening might result from eclipses by nearly edge-on flared (dusty or gaseous) disks.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- August 2011
- DOI:
- 10.1051/0004-6361/201117320
- arXiv:
- arXiv:1107.3517
- Bibcode:
- 2011A&A...532L..12B
- Keywords:
-
- accretion;
- accretion disks;
- scattering;
- binaries: eclipsing;
- circumstellar matter;
- stars: individual:ɛAur;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- A&