The Habitability and Stability of Earth-Like Planets in Binary Star Systems
Date
2012-5
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of Delaware
Abstract
In 2011, NASA's Kepler spacecraft observed the first planet to be detected in
a known binary star system, Kepler 16-b. Its discovery has sparked new discussion on
the potential of binary systems supporting habitable Earth-like planets. In this study,
by using relatively simple computation models, we are able to shed new light and
place new limitations on this discussion. Habitable Zone geometry in binary systems
is discussed as a part of this study, in which we are able to classify binary habitable
zones into two major classes of merged and unmerged, with important special cases of
each class presented. We were able to learn a good deal about the behavior of planets
in S-type binary orbits, and the possibility of life on those planets. The effect of the
orbit of the planet on the climate as well as how the planet experiences day and night
are discussed, and we also present a lower limit for the binary separation at which a
binary system would fail to have a habitable S-type orbit. In addition, we explore the
possibility that a planet could remain habitable in a transfer orbit between the system's
two stars or in orbit around one of the system's Lagrange Points. In this endeavor, we
derive an analytical expression for the surface temperature of an Earth-like planet at
a binary system's stable L4 and L5 Lagrange Points, which closely match simulated
results. We find definite possibilities for habitable L4 and L5 Lagrange Points in binary
systems over a wide range of stellar masses and mass ratios. Finally, we propose many
extensions and improvements to this study that would be worthwhile to pursue.
Description
Keywords
binary star systems, Earth-like planets, S-type binary orbits, binary habitable zones