A coplanar circumbinary protoplanetary disk in the TWA 3 triple M dwarf system. (arXiv:2102.11875v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Czekala_I/0/1/0/all/0/1">Ian Czekala</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ribas_A/0/1/0/all/0/1">Álvaro Ribas</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cuello_N/0/1/0/all/0/1">Nicolás Cuello</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chiang_E/0/1/0/all/0/1">Eugene Chiang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Macias_E/0/1/0/all/0/1">Enrique Macías</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Duchene_G/0/1/0/all/0/1">Gaspard Duchêne</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Andrews_S/0/1/0/all/0/1">Sean M. Andrews</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Espaillat_C/0/1/0/all/0/1">Catherine C. Espaillat</a>
We present sensitive ALMA observations of TWA~3, a nearby, young ($sim$10
Myr) hierarchical system composed of three pre-main sequence M3–M4.5 stars.
For the first time, we detected ${}^{12}$CO and ${}^{13}$CO $J$=2-1 emission
from the circumbinary protoplanetary disk around TWA~3A. We jointly fit the
protoplanetary disk velocity field, stellar astrometric positions, and stellar
radial velocities to infer the architecture of the system. The Aa and Ab stars
($0.29pm0.01,M_odot$ and $0.24pm0.01,M_odot$, respectively) comprising
the tight ($P=35$ days) eccentric ($e=0.63pm0.01$) spectroscopic binary are
coplanar with their circumbinary disk (misalignment $< 6^{circ}$ with 68%
confidence), similar to other short-period binary systems. From models of the
spectral energy distribution, we found the inner radius of the circumbinary
disk ($r_mathrm{inner} = 0.50 – 0.75$ au) to be consistent with theoretical
predictions of dynamical truncation $r_mathrm{cav}/a_mathrm{inner} approx
3$. The outer orbit of the tertiary star B ($0.40pm0.28,M_odot$, $asim65
pm 18$ au, $e=0.3pm0.2$) is not as well constrained as the inner orbit,
however, orbits coplanar with the A system are still preferred (misalignment $
< 20^{circ}$). To better understand the influence of the B orbit on the TWA 3A
circumbinary disk, we performed SPH simulations of the system and found that
the outer edge of the gas disk ($r_mathrm{outer}=8.5pm0.2$ au) is most
consistent with truncation from a coplanar, circular or moderately eccentric
orbit, supporting the preference from the joint orbital fit.
We present sensitive ALMA observations of TWA~3, a nearby, young ($sim$10
Myr) hierarchical system composed of three pre-main sequence M3–M4.5 stars.
For the first time, we detected ${}^{12}$CO and ${}^{13}$CO $J$=2-1 emission
from the circumbinary protoplanetary disk around TWA~3A. We jointly fit the
protoplanetary disk velocity field, stellar astrometric positions, and stellar
radial velocities to infer the architecture of the system. The Aa and Ab stars
($0.29pm0.01,M_odot$ and $0.24pm0.01,M_odot$, respectively) comprising
the tight ($P=35$ days) eccentric ($e=0.63pm0.01$) spectroscopic binary are
coplanar with their circumbinary disk (misalignment $< 6^{circ}$ with 68%
confidence), similar to other short-period binary systems. From models of the
spectral energy distribution, we found the inner radius of the circumbinary
disk ($r_mathrm{inner} = 0.50 – 0.75$ au) to be consistent with theoretical
predictions of dynamical truncation $r_mathrm{cav}/a_mathrm{inner} approx
3$. The outer orbit of the tertiary star B ($0.40pm0.28,M_odot$, $asim65
pm 18$ au, $e=0.3pm0.2$) is not as well constrained as the inner orbit,
however, orbits coplanar with the A system are still preferred (misalignment $
< 20^{circ}$). To better understand the influence of the B orbit on the TWA 3A
circumbinary disk, we performed SPH simulations of the system and found that
the outer edge of the gas disk ($r_mathrm{outer}=8.5pm0.2$ au) is most
consistent with truncation from a coplanar, circular or moderately eccentric
orbit, supporting the preference from the joint orbital fit.
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