The OATMEAL Survey. I. Low Stellar Obliquity in the Transiting Brown Dwarf System GPX-1

Creators: Giacalone, Steven¹; Dai, Fei^{1, 2}; Zanazzi, J. J.³; Howard, Andrew W.¹; Dressing, Courtney D.³; Winn, Joshua N.⁴; Rubenzahl, Ryan A.¹; Carmichael, Theron W.²; Vowell, Noah^{5, 6}; Kesseli, Aurora^{1, 7}; Halverson, Samuel⁸; Isaacson, Howard^{3, 9}; Brodheim, Max¹⁰; Deich, William¹¹; Fulton, Benjamin J.¹; Gibson, Steven R.¹; Hill, Grant M.¹⁰; Holden, Bradford¹¹; Householder, Aaron¹²; Kaye, Stephen¹; Laher, Russ R.¹³; Lanclos, Kyle¹⁰; Payne, Joel¹⁰; Petigura, Erik A.¹⁴; Roy, Arpita¹⁵; Schwab, Christian¹⁶; Shaum, Abby P.¹; Sirk, Martin M.³; Smith, Chris³; Stefánsson, Guðmundur¹⁷; Walawender, Josh¹⁰; Wang, Sharon X.¹⁸; Weiss, Lauren M.¹⁹; Yeh, Sherry¹⁰

1. California Institute of Technology
2. University of Hawaii at Manoa
3. University of California, Berkeley
4. Princeton University
5. Harvard-Smithsonian Center for Astrophysics
6. Michigan State University
7. Infrared Processing and Analysis Center
8. Jet Propulsion Lab
9. University of Southern Queensland
10. W.M. Keck Observatory
11. University of California, Santa Cruz
12. Massachusetts Institute of Technology
13. NASA Exoplanet Science Institute
14. University of California, Los Angeles
15. Schmidt Sciences
16. Macquarie University
17. University of Amsterdam
18. Tsinghua University
19. University of Notre Dame

Abstract

We introduce the OATMEAL survey, an effort to measure the obliquities of stars with transiting brown dwarf companions. We observed a transit of the close-in (P_orb = 1.74 days) brown dwarf GPX-1 b using the Keck Planet Finder spectrograph to measure the sky-projected angle between its orbital axis and the spin axis of its early F-type host star (λ). We measured λ = 69 ± 100, suggesting an orbit that is prograde and well aligned with the stellar equator. Hot Jupiters around early F stars are frequently found to have highly misaligned orbits, with polar and retrograde orbits being commonplace. It has been theorized that these misalignments stem from dynamical interactions, such as von Zeipel–Kozai–Lidov cycles, and are retained over long timescales due to weak tidal dissipation in stars with radiative envelopes. By comparing GPX-1 to similar systems under the frameworks of different tidal evolution theories, we argued that the rate of tidal dissipation is too slow to have re-aligned the system. This suggests that GPX-1 may have arrived at its close-in orbit via coplanar high-eccentricity migration or migration through an aligned protoplanetary disk. Our result for GPX-1 is one of few measurements of the obliquity of a star with a transiting brown dwarf. By enlarging the number of such measurements and comparing them with hot-Jupiter systems, we will more clearly discern the differences between the mechanisms that dictate the formation and evolution of both classes of objects.

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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.

Acknowledgement

We thank Luke Bouma for his useful feedback and suggestions.

The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Keck Observatory occupies the summit of Maunakea, a place of significant ecological, cultural, and spiritual importance within the indigenous Hawaiian community. We understand and embrace our accountability to Maunakea and the indigenous Hawaiian community, and commit to our role in long-term mutual stewardship. We are most fortunate to have the opportunity to conduct observations from Maunakea.

We gratefully acknowledge the efforts and dedication of the Keck Observatory staff for support of KPF and remote observing.

S.G. is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-2303922.

This research was carried out, in part, at the Jet Propulsion Laboratory and the California Institute of Technology under a contract with the National Aeronautics and Space Administration and funded through the President's and Director's Research & Development Fund Program.

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The OATMEAL Survey. I. Low Stellar Obliquity in the Transiting Brown Dwarf System GPX-1

Abstract

Copyright and License

Acknowledgement

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