The First Spin-Orbit Obliquity of an M dwarf/brown dwarf System: An eccentric and aligned TOI-2119 b

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Main Authors: Doyle, Lauren, Cañas, Caleb I., Libby-Roberts, Jessica E., Cegla, Heather M., Stefánsson, Guðmundur K., Anderson, David, Armstrong, David J., Bender, Chad, Bayliss, Daniel, Carmichael, Theron W., Casewell, Sarah, Kanodia, Shubham, Lafarga, Marina, Lin, Andrea S. J., Mahadevan, Suvrath, Monson, Andy, Robertson, Paul, Veras, Dimitri
Format: Preprint
Published: 2024
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author Doyle, Lauren
Cañas, Caleb I.
Libby-Roberts, Jessica E.
Cegla, Heather M.
Stefánsson, Guðmundur K.
Anderson, David
Armstrong, David J.
Bender, Chad
Bayliss, Daniel
Carmichael, Theron W.
Casewell, Sarah
Kanodia, Shubham
Lafarga, Marina
Lin, Andrea S. J.
Mahadevan, Suvrath
Monson, Andy
Robertson, Paul
Veras, Dimitri
author_facet Doyle, Lauren
Cañas, Caleb I.
Libby-Roberts, Jessica E.
Cegla, Heather M.
Stefánsson, Guðmundur K.
Anderson, David
Armstrong, David J.
Bender, Chad
Bayliss, Daniel
Carmichael, Theron W.
Casewell, Sarah
Kanodia, Shubham
Lafarga, Marina
Lin, Andrea S. J.
Mahadevan, Suvrath
Monson, Andy
Robertson, Paul
Veras, Dimitri
contents We report the first instance of an M dwarf/brown dwarf obliquity measurement for the TOI-2119 system using the Rossiter-McLaughlin effect. TOI-2119 b is a transiting brown dwarf orbiting a young, active early M dwarf ($T_{\rm{eff}}$ = 3553 K). It has a mass of 64.4 M$_{\rm{J}}$ and radius of 1.08 R$_{\rm{J}}$, with an eccentric orbit ($e$ = 0.3) at a period of 7.2 days. For this analysis, we utilise NEID spectroscopic transit observations and ground based simultaneous transit photometry from the Astrophysical Research Consortium (ARC) and the Las Campanas Remote Observatory (LCRO). We fit all available data of TOI-2119 b to refine the brown dwarf parameters and update the ephemeris. The classical Rossiter-McLaughlin technique yields a projected star-planet obliquity of $λ=-0.8\pm1.1^\circ$ and a three-dimensional obliquity of $ψ=15.7\pm5.5^\circ$. Additionally, we spatially resolve the stellar surface of TOI-2119 utilising the Reloaded Rossiter-McLaughlin technique to determine the projected star-planet obliquity as $λ=1.26 \pm 1.3^{\circ}$. Both of these results agree within $2σ$ and confirm the system is aligned, where TOI-2119 b joins an emerging group of aligned brown dwarf obliquities. We also probe stellar surface activity on the surface of TOI-2119 in the form of centre-to-limb variations as well as the potential for differential rotation. Overall, we find tentative evidence for centre-to-limb variations on the star but do not detect evidence of differential rotation.
format Preprint
id arxiv_https___arxiv_org_abs_2411_18567
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The First Spin-Orbit Obliquity of an M dwarf/brown dwarf System: An eccentric and aligned TOI-2119 b
Doyle, Lauren
Cañas, Caleb I.
Libby-Roberts, Jessica E.
Cegla, Heather M.
Stefánsson, Guðmundur K.
Anderson, David
Armstrong, David J.
Bender, Chad
Bayliss, Daniel
Carmichael, Theron W.
Casewell, Sarah
Kanodia, Shubham
Lafarga, Marina
Lin, Andrea S. J.
Mahadevan, Suvrath
Monson, Andy
Robertson, Paul
Veras, Dimitri
Earth and Planetary Astrophysics
Solar and Stellar Astrophysics
We report the first instance of an M dwarf/brown dwarf obliquity measurement for the TOI-2119 system using the Rossiter-McLaughlin effect. TOI-2119 b is a transiting brown dwarf orbiting a young, active early M dwarf ($T_{\rm{eff}}$ = 3553 K). It has a mass of 64.4 M$_{\rm{J}}$ and radius of 1.08 R$_{\rm{J}}$, with an eccentric orbit ($e$ = 0.3) at a period of 7.2 days. For this analysis, we utilise NEID spectroscopic transit observations and ground based simultaneous transit photometry from the Astrophysical Research Consortium (ARC) and the Las Campanas Remote Observatory (LCRO). We fit all available data of TOI-2119 b to refine the brown dwarf parameters and update the ephemeris. The classical Rossiter-McLaughlin technique yields a projected star-planet obliquity of $λ=-0.8\pm1.1^\circ$ and a three-dimensional obliquity of $ψ=15.7\pm5.5^\circ$. Additionally, we spatially resolve the stellar surface of TOI-2119 utilising the Reloaded Rossiter-McLaughlin technique to determine the projected star-planet obliquity as $λ=1.26 \pm 1.3^{\circ}$. Both of these results agree within $2σ$ and confirm the system is aligned, where TOI-2119 b joins an emerging group of aligned brown dwarf obliquities. We also probe stellar surface activity on the surface of TOI-2119 in the form of centre-to-limb variations as well as the potential for differential rotation. Overall, we find tentative evidence for centre-to-limb variations on the star but do not detect evidence of differential rotation.
title The First Spin-Orbit Obliquity of an M dwarf/brown dwarf System: An eccentric and aligned TOI-2119 b
topic Earth and Planetary Astrophysics
Solar and Stellar Astrophysics
url https://arxiv.org/abs/2411.18567