The First Spin-Orbit Obliquity of an M dwarf/brown dwarf system: an eccentric and aligned TOI-2119 b
ABSTRACT 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 d. For this analysis, we utilize NEID spectroscopic transit observations and ground-based simultaneous transit photometry from the Astrophysical Research Consortium and the Las Campanas Remote Observatory. 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 $\lambda =-0.8\pm 1.1^\circ$ and a three-dimensional obliquity of $\psi =15.7\pm 5.5^\circ$. Additionally, we spatially resolve the stellar surface of TOI-2119 utilizing the Reloaded Rossiter–McLaughlin technique to determine the projected star–planet obliquity as $\lambda =1.26 \pm 1.3^{\circ }$. Both of these results agree within $2\sigma$ 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.
Authors
- Lauren Doyle (ORCID: https://orcid.org/0000-0002-9365-2555)
- Dimitri Veras (ORCID: https://orcid.org/0000-0001-8014-6162)
- Theron W. Carmichael (ORCID: https://orcid.org/0000-0001-6416-1274)
- Caleb I. Cañas (ORCID: https://orcid.org/0000-0003-4835-0619)
- Chad F. Bender (ORCID: https://orcid.org/0000-0003-4384-7220)
- Daniel Bayliss (ORCID: https://orcid.org/0000-0001-6023-1335)
- D. J. Armstrong (ORCID: https://orcid.org/0000-0002-5080-4117)
- Jessica E. Libby-Roberts (ORCID: https://orcid.org/0000-0002-2990-7613)
- Shubham Kanodia (ORCID: https://orcid.org/0000-0001-8401-4300)
- S. L. Casewell (ORCID: https://orcid.org/0000-0003-2478-0120)
- Paul M. Robertson (ORCID: https://orcid.org/0000-0003-0149-9678)
- Andrea S. J. Lin (ORCID: https://orcid.org/0000-0002-9082-6337)
- M. Lafarga (ORCID: https://orcid.org/0000-0002-8815-9416)
- D. R. Anderson (ORCID: https://orcid.org/0000-0001-7416-7522)
- Suvrath Mahadevan (ORCID: https://orcid.org/0000-0001-9596-7983)
- H. M. Cegla (ORCID: https://orcid.org/0000-0001-8934-7315)
- Gumundur Stefánsson
- Andy Monson
Institutions
- Goddard Space Flight Center (US)
- Pennsylvania State University (US)
- University of Hawaii System (US)
- University of Arizona (US)
- University of Leicester (GB)
- Carnegie Institution for Science (US)
- University of California, Irvine (US)
- Universidad Católica del Norte (CL)
- University of Warwick (GB)
- Université Bourgogne Franche-Comté (FR)
- Astronomical Institute of the Slovak Academy of Sciences (SK)
- University of Amsterdam (NL)
Publication Details
- Journal
- Monthly Notices of the Royal Astronomical Society
- Published
- 2024-12-31
- DOI
- https://doi.org/10.1093/mnras/stae2819
- Citations
- 9
- Primary Topic
- Stellar, planetary, and galactic studies
- Type
- article
- Field-Weighted Citation Impact
- 2.98
Funders
- National Science Foundation
- National Aeronautics and Space Administration
- UK Research and Innovation
- Science and Technology Facilities Council