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Stellar Companions to TESS Objects of Interest: A Test of Planet-Companion Alignment

Behmard, Aida and Dai, Fei and Howard, Andrew W. (2022) Stellar Companions to TESS Objects of Interest: A Test of Planet-Companion Alignment. . (Unpublished)

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We present a catalog of stellar companions to host stars of TESS Objects of Interest (TOIs) identified from a marginalized likelihood ratio test that incorporates astrometric data from the Gaia Early Data Release 3 catalog (EDR3). The likelihood ratio is computed using a probabilistic model that incorporates parallax and proper motion covariances and marginalizes the distances and 3D velocities of stars in order to identify comoving stellar pairs. We find 172 comoving companions to 170 non-false positive TOI hosts, consisting of 168 systems with two stars and 2 systems with three stars. Amongst the 170 TOI hosts, 54 harbor confirmed planets that span a wide range of system architectures. We conduct an investigation of the mutual inclinations between the stellar companion and planetary orbits using Gaia EDR3, which is possible because transiting exoplanets must orbit within the line-of-sight, thus stellar companion kinematics can constrain mutual inclinations. While the statistical significance of the current sample is weak, we find that 73⁺¹⁴₋₂₀% of systems with Kepler-like architectures (R_P ≤ 4 R_⊕ and a < 1 AU) appear to favor a non-isotropic orientation between the planetary and companion orbits with a typical mutual inclination α of 35 ± 24∘. In contrast, 65⁺²⁰₋₃₅% of systems with close-in giants (P < 10 days and R_P > 4 R_⊕) favor a perpendicular geometry (α = 89 ± 21∘) between the planet and companion. Moreover, the close-in giants with large stellar obliquities (planet-host misalignment) are also those that favor significant planet-companion misalignment.

Item Type:Report or Paper (Discussion Paper)
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URLURL TypeDescription Paper
Behmard, Aida0000-0003-0012-9093
Dai, Fei0000-0002-8958-0683
Howard, Andrew W.0000-0001-8638-0320
Additional Information:Attribution 4.0 International (CC BY 4.0). We thank Dan Fabrycky, Josh Winn, and Heather Knutson for insightful comments that improved the final manuscript. A.B. acknowledges funding from the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1745301. Software: Astropy (Astropy Collaboration et al. 2013, 2018)
Group:Astronomy Department
Funding AgencyGrant Number
NSF Graduate Research FellowshipDGE-1745301
Record Number:CaltechAUTHORS:20220228-183332903
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:113657
Deposited By: George Porter
Deposited On:28 Feb 2022 21:43
Last Modified:28 Feb 2022 21:43

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