Abstract
The discovery of exosolar planets in binary star systems and particularly in narrow (< 20 AU) systems like for example Gamma Cephei (Campbell et al., 1988; Hatzes et al., 2003) or Alpha Centauri (Dumusque et al., 2012) has put special demands on planet formation theories. The tidal forces acting on the proto-planetery disk due to the binary companion change the structure of the disk drastically by creating massive spiral arms and making the disk excentric. In Müller and Kley (2012) we investigate this by two-dimensional simulations which include the heating of the disk due to viscous heating and pdV work and the cooling of the disk through local radiative cooling. We show that the disk becomes less eccentric compared to isothermal models, which makes planet formation more likely. These simulations do not take the self-gravity of the disk into account. To treat self-gravity correctly it is necessary to account for the vertical extend of the disk. As this is not directly possible in two-dimensional simulations the gravitational potential is smoothed by a smoothing parameter epsilon to get similar results. A similar problems occurs with the gravitational forces from a planet embedded in the disk. We address this problem in Müller et al. (2012) by comparing the real forces between two points within the disk or between a point within the disks and the planet with the approximated forces created by a smoothed potential. We identify values for epsilon which depend on the distance between the points or the point and the planet which give the best possible approximation. Until now, no planets have been observed during their formation phase. Transitional disks are proto-planetery disks with an inner hole which could be created by a planet. Therefore transitional disks are a hot candidate for observations of forming planets. Despite the inner hole, transitional disks show mass accretion onto the star. One possibilty to bring material through the gap onto the star is with the help of a planet. Additionally the disk gets eccentric for massive (> Mjup) planets and this also helps to push material through the gap. In Müller and Kley (2013) we investigate the accretion through the disk onto the star in isothermal and radiative simulations. All so far mentioned simulations were performed using the FARGO Code, which uses the FARGO algorithm (Masset, 2000) to speed-up calculations. The applicability of this algorithm to our problems has been put into question by Dong et al. (2011). The authors claim that very large resolutions and an additional timestep criterion are needed to produce correct results. We address these concerns in Kley et al. (2012) and show by comparison simulations with five different Codes that they are groundless. For planets in binary star system the question of habitability arises as well. In Müller and Haghighipour (2014) we extend work by Kaltenegger and Haghighipour (2013) and Haghighipour and Kaltenegger (2013) on habitability in binary star systems to the case multiple stellar systems. We show that the idea of an inner and outer radius of the habitable zone is not valid for multiple stellar systems and show an alternative definition. In addition we present and interactive website for calculating the habitable zones of multiple stellar systems.
Author and committee
dc:creator, dc:contributor.*- Author
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- Müller, Tobias Wolfgang Andreas
Identifiers
dc:identifier.*- Identifier
- hdl:10900/50022