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2006 Annual Science Report

University of Hawaii, Manoa Reporting  |  JUL 2005 – JUN 2006

Habitability and Water Delivery in Binary-Planetary Systems

Project Summary

In the last year, a systematic study was completed of the formation and stability of planets, both giant and terrestrial, in multiple planets systems, as well as binary star systems. The motivation behind this study comes from the fact that among more than 180 extrasolar planets discovered to-date, 18 are in multiple planets systems, and approximately 20% are within binary star systems. Among these binary-planetary systems, γ Cephei has been the focus of my research.

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Project Progress

In the last year, a systematic study was completed of the formation and stability of planets, both giant and terrestrial, in multiple planets systems, as well as binary star systems. The motivation behind this study comes from the fact that among more than 180 extrasolar planets discovered to-date, 18 are in multiple planets systems, and approximately 20% are within binary star systems. Among these binary-planetary systems, γ Cephei has been the focus of my research. This system consists of a 1.6 solar-mass star as its primary, an M dwarf, at a distance of 19 AU, as its secondary, and a Jupiter-like planet that revolves around the primary star at 2.1 AU. To study the habitability of this system, the entire parameter-space of this system has been mapped and regions have been identified where an Earth-like planet can be stable (Figure 1).

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The calculations have also been expanded to include interactions among planetesimals at different locations in binary-planetary system in order to understand the formation of terrestrial planets in system with two stars. Results indicated that, it is possible for a binary star system to harbor terrestrial-class planets in closer distances. This has motivated the launching of an expansive numerical study of the formation of habitable planets in a binary star system with a giant planet. The results that were obtained from a large survey of the parameter-space of such systems, have indicated that it is indeed possible to form an Earth-like planet in the habitable zone of a star in a binary system if the eccentricity of the binary and its giant planets are moderate (i.e., between 0.2-0.3). See Figure 2.

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  • PROJECT INVESTIGATORS:
    Nader Haghighipour Nader Haghighipour
    Project Investigator
  • RELATED OBJECTIVES:
    Objective 1.1
    Models of formation and evolution of habitable planets