Discovery of a Third Transiting Planet in the Kepler-47 Circumbinary System. (arXiv:1904.07255v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Orosz_J/0/1/0/all/0/1">Jerome A. Orosz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Welsh_W/0/1/0/all/0/1">William F. Welsh</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Haghighipour_N/0/1/0/all/0/1">Nader Haghighipour</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Quarles_B/0/1/0/all/0/1">Billy Quarles</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Short_D/0/1/0/all/0/1">Donald R. Short</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mills_S/0/1/0/all/0/1">Sean M. Mills</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Satyal_S/0/1/0/all/0/1">Suman Satyal</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Torres_G/0/1/0/all/0/1">Guillermo Torres</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Agol_E/0/1/0/all/0/1">Eric Agol</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fabrycky_D/0/1/0/all/0/1">Daniel C. Fabrycky</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jontof_Hutter_D/0/1/0/all/0/1">Daniel Jontof-Hutter</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Windmiller_G/0/1/0/all/0/1">Gur Windmiller</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Muller_T/0/1/0/all/0/1">Tobias W. A. Müller</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hinse_T/0/1/0/all/0/1">Tobias C. Hinse</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cochran_W/0/1/0/all/0/1">William D. Cochran</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Endl_M/0/1/0/all/0/1">Michael Endl</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ford_E/0/1/0/all/0/1">Eric B. Ford</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mazeh_T/0/1/0/all/0/1">Tsevi Mazeh</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lissauer_J/0/1/0/all/0/1">Jack J. Lissauer</a>
Of the nine confirmed transiting circumbinary planet systems, only Kepler-47
is known to contain more than one planet. Kepler-47 b (the “inner planet”) has
an orbital period of 49.5 days and a radius of about $3,R_{oplus}$. Kepler-47
c (the “outer planet”) has an orbital period of 303.2 days and a radius of
about $4.7,R_{oplus}$. Here we report the discovery of a third planet,
Kepler-47 d (the “middle planet”), which has an orbital period of 187.4 days
and a radius of about $7,R_{oplus}$. The presence of the middle planet allows
us to place much better constraints on the masses of all three planets, where
the $1sigma$ ranges are less than $26,M_{oplus}$, between
$7-43,M_{oplus}$, and between $2-5,M_{oplus}$ for the inner, middle, and
outer planets, respectively. The middle and outer planets have low bulk
densities, with $rho_{rm middle} < 0.68$ g cm$^{-3}$ and $rho_{rm outer} <
0.26$ g cm$^{-3}$ at the $1sigma$ level. The two outer planets are "tightly
packed," assuming the nominal masses, meaning no other planet could stably
orbit between them. All of the orbits have low eccentricities and are nearly
coplanar, disfavoring violent scattering scenarios and suggesting gentle
migration in the protoplanetary disk.
Of the nine confirmed transiting circumbinary planet systems, only Kepler-47
is known to contain more than one planet. Kepler-47 b (the “inner planet”) has
an orbital period of 49.5 days and a radius of about $3,R_{oplus}$. Kepler-47
c (the “outer planet”) has an orbital period of 303.2 days and a radius of
about $4.7,R_{oplus}$. Here we report the discovery of a third planet,
Kepler-47 d (the “middle planet”), which has an orbital period of 187.4 days
and a radius of about $7,R_{oplus}$. The presence of the middle planet allows
us to place much better constraints on the masses of all three planets, where
the $1sigma$ ranges are less than $26,M_{oplus}$, between
$7-43,M_{oplus}$, and between $2-5,M_{oplus}$ for the inner, middle, and
outer planets, respectively. The middle and outer planets have low bulk
densities, with $rho_{rm middle} < 0.68$ g cm$^{-3}$ and $rho_{rm outer} <
0.26$ g cm$^{-3}$ at the $1sigma$ level. The two outer planets are “tightly
packed,” assuming the nominal masses, meaning no other planet could stably
orbit between them. All of the orbits have low eccentricities and are nearly
coplanar, disfavoring violent scattering scenarios and suggesting gentle
migration in the protoplanetary disk.
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