Orbital Parameter Determination for Wide Stellar Binary Systems in the Age of textit{Gaia}. (arXiv:2003.11106v1 [astro-ph.SR])

Orbital Parameter Determination for Wide Stellar Binary Systems in the Age of textit{Gaia}. (arXiv:2003.11106v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Pearce_L/0/1/0/all/0/1">Logan A. Pearce</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kraus_A/0/1/0/all/0/1">Adam L. Kraus</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dupuy_T/0/1/0/all/0/1">Trent J. Dupuy</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mann_A/0/1/0/all/0/1">Andrew W. Mann</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Newton_E/0/1/0/all/0/1">Elisabeth R. Newton</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tofflemire_B/0/1/0/all/0/1">Benjamin N. Tofflemire</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vanderburg_A/0/1/0/all/0/1">Andrew W. Vanderburg</a>

The orbits of binary stars and planets, particularly eccentricities and
inclinations, encode the angular momentum within these systems. Within stellar
multiple systems, the magnitude and (mis)alignment of angular momentum vectors
among stars, disks, and planets probes the complex dynamical processes guiding
their formation and evolution. The accuracy of the textit{Gaia} catalog can be
exploited to enable comparison of binary orbits with known planet or disk
inclinations without costly long-term astrometric campaigns. We show that
textit{Gaia} astrometry can place meaningful limits on orbital elements in
cases with reliable astrometry, and discuss metrics for assessing the
reliability of textit{Gaia} DR2 solutions for orbit fitting. We demonstrate
our method by determining orbital elements for three systems (DS Tuc AB, GK/GI
Tau, and Kepler-25/KOI-1803) using textit{Gaia} astrometry alone. We show that
DS Tuc AB’s orbit is nearly aligned with the orbit of DS Tuc Ab, GK/GI Tau’s
orbit might be misaligned with their respective protoplanetary disks, and the
Kepler-25/KOI-1803 orbit is not aligned with either component’s transiting
planetary system. We also demonstrate cases where textit{Gaia} astrometry
alone fails to provide useful constraints on orbital elements. To enable
broader application of this technique, we introduce the python tool
texttt{lofti_gaiaDR2} to allow users to easily determine orbital element
posteriors.

The orbits of binary stars and planets, particularly eccentricities and
inclinations, encode the angular momentum within these systems. Within stellar
multiple systems, the magnitude and (mis)alignment of angular momentum vectors
among stars, disks, and planets probes the complex dynamical processes guiding
their formation and evolution. The accuracy of the textit{Gaia} catalog can be
exploited to enable comparison of binary orbits with known planet or disk
inclinations without costly long-term astrometric campaigns. We show that
textit{Gaia} astrometry can place meaningful limits on orbital elements in
cases with reliable astrometry, and discuss metrics for assessing the
reliability of textit{Gaia} DR2 solutions for orbit fitting. We demonstrate
our method by determining orbital elements for three systems (DS Tuc AB, GK/GI
Tau, and Kepler-25/KOI-1803) using textit{Gaia} astrometry alone. We show that
DS Tuc AB’s orbit is nearly aligned with the orbit of DS Tuc Ab, GK/GI Tau’s
orbit might be misaligned with their respective protoplanetary disks, and the
Kepler-25/KOI-1803 orbit is not aligned with either component’s transiting
planetary system. We also demonstrate cases where textit{Gaia} astrometry
alone fails to provide useful constraints on orbital elements. To enable
broader application of this technique, we introduce the python tool
texttt{lofti_gaiaDR2} to allow users to easily determine orbital element
posteriors.

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