Published May 2024 | Published
Journal Article Open

The TESS-Keck Survey. XVIII. A Sub-Neptune and Spurious Long-period Signal in the TOI-1751 System

  • 1. ROR icon University of California, Berkeley
  • 2. ROR icon Open University of Israel
  • 3. ROR icon University of California, Santa Cruz
  • 4. ROR icon University of Hawaii at Manoa
  • 5. ROR icon Princeton University
  • 6. ROR icon University of Kansas
  • 7. ROR icon California Institute of Technology
  • 8. ROR icon University of California, Riverside
  • 9. ROR icon California State University, San Marcos
  • 10. ROR icon University of Sydney
  • 11. ROR icon University of Southern Queensland
  • 12. ROR icon University of California, Irvine
  • 13. ROR icon University of California, Los Angeles
  • 14. ROR icon University of Copenhagen
  • 15. ROR icon Gemini North Observatory
  • 16. ROR icon Yale University
  • 17. ROR icon University of Notre Dame
  • 18. ROR icon Harvard-Smithsonian Center for Astrophysics
  • 19. ROR icon Technical University of Denmark
  • 20. ROR icon Ames Research Center
  • 21. ROR icon Goddard Space Flight Center
  • 22. ROR icon Search for Extraterrestrial Intelligence
  • 23. ROR icon Massachusetts Institute of Technology
  • 24. ROR icon Centro de Astrobiología
  • 25. ROR icon Catholic University of the Most Holy Conception
  • 26. ROR icon Vanderbilt University
  • 27. Planetary Discoveries

Abstract

We present and confirm TOI-1751 b, a transiting sub-Neptune orbiting a slightly evolved, solar-type, metal-poor star (Teff = 5996 ± 110 K, log(g)=4.2±0.1V = 9.3 mag, [Fe/H] = −0.40 ± 0.06 dex) every 37.47 days. We use TESS photometry to measure a planet radius of 2.77_(−0.07)_(+0.15)R⊕. We also use both Keck/HIRES and APF/Levy radial velocities (RV) to derive a planet mass of 14.5_(−3.14)_(+3.15)M⊕, and thus a planet density of 3.6 ± 0.9 g cm−3. There is also a long-period (∼400 days) signal that is observed in only the Keck/HIRES data. We conclude that this long-period signal is not planetary in nature and is likely due to the window function of the Keck/HIRES observations. This highlights the role of complementary observations from multiple observatories to identify and exclude aliases in RV data. Finally, we investigate the potential compositions of this planet, including rocky and water-rich solutions, as well as theoretical irradiated ocean models. TOI-1751 b is a warm sub-Neptune with an equilibrium temperature of ∼820 K. As TOI-1751 is a metal-poor star, TOI-1751 b may have formed in a water-enriched formation environment. We thus favor a volatile-rich interior composition for this planet.

Copyright and License

© 2024. 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.

Acknowledgement

Some of the data presented in this paper 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. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this sacred mountain which is now colonized land.

This paper made use of data collected by the TESS mission and is publicly available from the Mikulski Archive for Space Telescopes (MAST) operated by the Space Telescope Science Institute (STScI; MAST Team 2021). Funding for the TESS mission is provided by NASA's Science Mission Directorate. We acknowledge the use of public TESS data from pipelines at the TESS Science Office and at the TESS Science Processing Operations Center. Resources supporting this work were provided by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center for the production of the SPOC data products.

J. Akana Murphy, C. Brinkman, F. Dai, S. Giacalone, J. Lubin, M. Rice, and J. van Zandt contributed >10 observations of TOI-1751 using Keck/HIRES.

We thank Artem Aguichine for useful discussions on interpreting composition models and Andreia Carrillo for insight on the galactic context of TOI-1751. We also acknowledge Erik Petigura and BJ Fulton for their contributions to the construction, design, and team management of the TESS-Keck Survey.

M. Rice acknowledges support from the Heising-Simons Foundation grant. #2023-4478. J.M.A.M. is supported by the National Science Foundation (NSF) Graduate Research Fellowship Program (GRFP) under grant No. DGE-1842400. A.D. would like to acknowledge the UC Berkeley Physics Undergraduate Research Scholars Program and the UC Berkeley Mathematical & Physical Sciences Scholars for funding their work. E.V.T. acknowledges support from a David & Lucile Packard Foundation grant. C.H. acknowledges support from the National Science Foundation Graduate Research Fellowship Program under grant No. DGE 2146752. D.H. acknowledges support from the Alfred P. Sloan Foundation, the National Aeronautics and Space Administration (80NSSC21K0652), and the Australian Research Council (FT200100871). M.H. would like to acknowledge NASA support via the FINESST Planetary Science Division, NASA award number 80NSSC21K1536.

Facilities

Keck :I - , APF - , TESS - .

Software References

This research made use of exoplanet (Foreman-Mackey et al. 20212021) and its dependencies (Astropy Collaboration et al. 2013; Salvatier et al. 2016; Theano Development Team 2016; Astropy Collaboration et al. 2018; Kumar et al. 2019; Agol et al. 2020; Astropy Collaboration et al. 2022). This research also made use of Lightkurve, a Python package for Kepler and TESS data analysis (Lightkurve Collaboration et al. 2018), and its dependencies (Astropy Collaboration et al. 20132018; Brasseur et al. 2019; Ginsburg et al. 2019). Additionally, this work made use of the following Python packages: numpy (Harris et al. 2020), pandas (pandas development team 2020), matplotlib (Hunter 2007), corner (Foreman-Mackey 2016), RadVel (Fulton et al. 2018), SpecMatch-Emp (Yee et al. 2017), SpecMatch-Synth (Petigura et al. 2017), and CMasher (Van der Velden 2020).

Files

Desai_2024_AJ_167_194.pdf
Files (2.3 MB)
Name Size Download all
md5:d61d5c937e3fb2f528d6f15063d2a9e8
2.3 MB Preview Download

Additional details

Created:
February 28, 2025
Modified:
February 28, 2025