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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. Astronomical Journal, 163 (4). Art. No. 160. ISSN 0004-6256. doi:10.3847/1538-3881/ac53a7.

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We present a catalog of stellar companions to host stars of Transiting Exoplanet Survey Satellite 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. Among 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 nonisotropic 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:Article
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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:© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2021 October 8; revised 2022 January 24; accepted 2022 February 8; published 2022 March 11. We thank Dan Fabrycky, Josh Winn, Simon Albrect, 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. DGE1745301. Software: Astropy (Astropy Collaboration et al. 2013, 2018).
Group:Astronomy Department
Funding AgencyGrant Number
NSF Graduate Research FellowshipDGE-1745301
Subject Keywords:Binary stars; Exoplanet dynamics; Astrometry; Bayesian statistics; Hierarchical models
Issue or Number:4
Classification Code:Unified Astronomy Thesaurus concepts: Binary stars (154); Exoplanet dynamics (490); Astrometry (80); Bayesian statistics (1900); Hierarchical models (1925)
Record Number:CaltechAUTHORS:20220315-625037000
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Official Citation:Aida Behmard et al 2022 AJ 163 160
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:113907
Deposited By: George Porter
Deposited On:17 Mar 2022 19:54
Last Modified:17 Mar 2022 19:54

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