Discovery and Characterization of the TOI-4468 Planetary System: A Transiting Hot Jupiter with a Lone Nearby Outer Companion
Abstract We report the discovery of two planets, a hot Jupiter (HJ) and a nearby outer sub-Neptune, orbiting the star TOI-4468. This system is unique among the current exoplanet census in that it features a close outer companion to a HJ without an accompanying inner companion. By jointly fitting radial velocity (RV) measurements taken with the NEID spectrograph and transit photometry from the Transiting Exoplanet Survey Satellite (TESS) and several ground-based observatories, we constrain the orbital periods, masses, and radii of these two planets. We confirm the planetary nature of the HJ TOI-4468 b ( R = 1.01 R J , m = 0.54 M J , P = 2.77 days). We also validate the outer planet TOI-4468 c ( R = 0.28 R J , P = 7.01 days) statistically, incorporating constraints from ground-based observations. We also identify, but cannot confirm, an additional RV signal that may be due to an outer giant in this system with an orbital period of 624 days. From the observed geometry of this system, we argue that it must never have encountered an early secular resonance that is thought to excite the mutual inclination of other HJ/outer companion systems. We discuss the possibility of an undetected inner companion, as well as potential implications for HJ formation.
Authors
- Ivan A. Strakhov (ORCID: https://orcid.org/0000-0003-0647-6133)
- Robert Aloisi (ORCID: https://orcid.org/0000-0003-2822-616X)
- Benjamin J. Hord (ORCID: https://orcid.org/0000-0001-5084-4269)
- H. Parviainen (ORCID: https://orcid.org/0000-0001-5519-1391)
- Karen A. Collins (ORCID: https://orcid.org/0000-0001-6588-9574)
- Adam Popowicz (ORCID: https://orcid.org/0000-0003-3184-5228)
- Richard P. Schwarz (ORCID: https://orcid.org/0000-0001-8227-1020)
- Andrew M. Vanderburg (ORCID: https://orcid.org/0000-0001-7246-5438)
- Thomas G. Beatty (ORCID: https://orcid.org/0000-0002-9539-4203)
- Melinda Soares-Furtado (ORCID: https://orcid.org/0000-0001-7493-7419)
- Guđmundur Stefánsson (ORCID: https://orcid.org/0000-0001-7409-5688)
- Lizhou Sha (ORCID: https://orcid.org/0000-0001-5401-8079)
- Joseph R. Livesey (ORCID: https://orcid.org/0000-0003-3888-3753)
- Joseph E. Rodriguez (ORCID: https://orcid.org/0000-0001-8812-0565)
- Keivan Guadalupe Stassun (ORCID: https://orcid.org/0000-0002-3481-9052)
- Manfred Raetz (ORCID: https://orcid.org/0000-0002-2190-3319)
- Alyssa R. Jankowski (ORCID: https://orcid.org/0000-0003-4287-004X)
- Fabian Rodriguez Frustaglia
- Eva Stafne (ORCID: https://orcid.org/0009-0001-2913-792X)
- Juliette Becker
- Maxwell A. Kroft (ORCID: https://orcid.org/0009-0002-2757-4138)
- Thomas MacLean
- Judith Korth (ORCID: https://orcid.org/0000-0002-0076-6239)
- Chelsea X. Huang
- Khalid Barkaoui
- Coleman Nelson (ORCID: https://orcid.org/0009-0009-2277-799X)
- Elise Koo (ORCID: https://orcid.org/0009-0007-0740-0954)
- Paul Foster
- Zijun He
- Kinga Kasprzyk
- Devansh Mathur
Institutions
- Silesian University of Technology (PL)
- California Institute of Technology (US)
- Goddard Space Flight Center (US)
- University of Wisconsin–Madison (US)
- University of Liège (BE)
- Universidad de La Laguna (ES)
- University of Southern Queensland (AU)
- Lund University (SE)
- Lomonosov Moscow State University (RU)
- Vanderbilt University (US)
- Princeton University (US)
- California State University Los Angeles (US)
- Center for Astrophysics Harvard & Smithsonian (US)
- Instituto de Astrofísica de Canarias (ES)
- Massachusetts Institute of Technology (US)
- Michigan State University (US)
- University of Amsterdam (NL)
- Netherlands Institute for Radio Astronomy (NL)
- Stanford University (US)
Publication Details
- Journal
- The Astronomical Journal
- Published
- 2026-10-29
- DOI
- https://doi.org/10.3847/1538-3881/aeaee4
- Primary Topic
- Stellar, planetary, and galactic studies
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- National Science Foundation
- National Aeronautics and Space Administration
- Wisconsin Alumni Research Foundation
- Oak Ridge Associated Universities
- University of Pennsylvania
- California Institute of Technology
- University of Wisconsin-Madison
- Pennsylvania State University
- NASA Exoplanet Science Institute
- Universidad de La Laguna
- European Commission
- Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung
- Ministry of Science, ICT and Future Planning
- Vetenskapsrådet
- Ministerio de Ciencia e Innovación
- Lomonosov Moscow State University
- Goddard Space Flight Center
- Science Mission Directorate
- Office of the Vice Chancellor for Research, University of Illinois at Chicago
- Ministerio de Universidades