The Eccentricity Distribution of Binary Star Systems at the Onset of Roche Lobe Overflow
Abstract
While it is commonly assumed that tidal friction will circularize any interacting binary systems prior to the onset of Roche Lobe Overflow (RLO), state-of-the-art population synthesis codes (e.g., StarTrack, Belczynski et al., 2008) have found that this tidal effect may not be strong enough to fully circularize the binary prior to RLO. To investigate this important class of systems, we examine the parameter distribution of systems with a non-zero eccentricity at the onset of RLO. Since there are very few systems observed to undergo eccentric RLO, it is expected that, if it exists, such an eccentric mass transfer phase is short-lived. Using the parameter distribution at the onset of eccentric RLO, we compare the static tidal evolution timescales to the timescales expected via mass transfer effects (see, e.g., Sepinsky et al. 2007b). Furthermore, asynchronous rotation and a non-zero eccentricity can significantly decrease the size of the Roche Lobe, causing RLO to occur even earlier in the binary lifetime than otherwise expect (Sepinsky, Willems, and Kalogera 2007a). Thus, we also update the calculation of the Roche Lobe Radius to include asynchronous rotation and non-zero eccentricity, noting the change in the parameter distribution for the two cases.
- Publication:
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American Astronomical Society Meeting Abstracts #219
- Pub Date:
- January 2012
- Bibcode:
- 2012AAS...21915345C