TOI-1408: Discovery and Photodynamical Modeling of a Small Inner Companion to a Hot Jupiter Revealed by Transit Timing Variations
Journal article, 2024

We report the discovery and characterization of a small planet, TOI-1408 c, on a 2.2 day orbit located interior to a previously known hot Jupiter, TOI-1408 b (P = 4.42 days, M = 1.86 ± 0.02 M Jup, R = 2.4 ± 0.5 R Jup) that exhibits grazing transits. The two planets are near 2:1 period commensurability, resulting in significant transit timing variations (TTVs) for both planets and transit duration variations for the inner planet. The TTV amplitude for TOI-1408 c is 15% of the planet’s orbital period, marking the largest TTV amplitude relative to the orbital period measured to date. Photodynamical modeling of ground-based radial velocity (RV) observations and transit light curves obtained with the Transiting Exoplanet Survey Satellite and ground-based facilities leads to an inner planet radius of 2.22 ± 0.06 R ⊕ and mass of 7.6 ± 0.2 M ⊕ that locates the planet into the sub-Neptune regime. The proximity to the 2:1 period commensurability leads to the libration of the resonant argument of the inner planet. The RV measurements support the existence of a third body with an orbital period of several thousand days. This discovery places the system among the rare systems featuring a hot Jupiter accompanied by an inner low-mass planet.

Author

Judith Korth

Lund University

Priyanka Chaturvedi

Tata Institute of Fundamental Research

Thüringer Landessternwarte Tautenburg

H. Parviainen

Instituto de Astrofísica de Canarias

University of La Laguna

Ilaria Carleo

University of La Laguna

Istituto nazionale di astrofisica (INAF)

Instituto de Astrofísica de Canarias

Michael Endl

College of Natural Sciences

The University of Texas at Austin

E. W. Guenther

Thüringer Landessternwarte Tautenburg

G. Nowak

Instituto de Astrofísica de Canarias

University of La Laguna

Nicolaus Copernicus University

Carina Persson

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics

P. MacQueen

College of Natural Sciences

A. J. Mustill

Lund University

J. Cabrera

German Aerospace Center (DLR)

William D. Cochran

The University of Texas at Austin

College of Natural Sciences

J. Lillo-Box

Centro de Astrobiologia (CAB)

D. Hobbs

Lund University

F. Murgas

Instituto de Astrofísica de Canarias

University of La Laguna

Michael Greklek-McKeon

California Institute of Technology (Caltech)

Hanna Kellermann

Ludwig Maximilian University of Munich (LMU)

G. Hebrard

Centre national de la recherche scientifique (CNRS)

Institut d 'Astrophysique de Paris

A. Fukui

Instituto de Astrofísica de Canarias

University of Tokyo

Enric Palle

Instituto de Astrofísica de Canarias

University of La Laguna

Jon M. Jenkins

National Aeronautics and Space Administration (NASA)

J. D. Twicken

SETI Institute

National Aeronautics and Space Administration (NASA)

Karen A. Collins

Harvard-Smithsonian Center for Astrophysics

Samuel N. Quinn

Harvard-Smithsonian Center for Astrophysics

J. Šubjak

Czech Academy of Sciences

Harvard-Smithsonian Center for Astrophysics

P. G. Beck

Instituto de Astrofísica de Canarias

University of La Laguna

D. Gandolfi

University of Turin

S. Mathur

Instituto de Astrofísica de Canarias

University of La Laguna

H. Deeg

University of La Laguna

Instituto de Astrofísica de Canarias

D. W. Latham

Harvard-Smithsonian Center for Astrophysics

Simon Albrecht

Aarhus University

D. Barrado

Centro de Astrobiologia (CAB)

I. Boisse

Centre national de la recherche scientifique (CNRS)

Laboratoire d'Astrophysique de Marseille

Hervé Bouy

Laboratoire d'Astrophysique de Bordeaux

Institut Universitaire de France

X. Delfosse

Institut de Planétologie et d’Astrophysique de Grenoble (IPAG)

O. Demangeon

University of Porto

R. A. García

University Paris-Saclay

A. Hatzes

Thüringer Landessternwarte Tautenburg

N. Heidari

Institut d 'Astrophysique de Paris

Kai Ikuta

University of Tokyo

Petr Kabath

Czech Academy of Sciences

H. Knutson

California Institute of Technology (Caltech)

J.H. Livingston

National Astronomical Observatory of Japan

National Institutes of Natural Sciences

The Graduate University for Advanced Studies (SOKENDAI)

E. Martioli

Laboratorio Nacional de Astrofisica, Itajuba

Institut d 'Astrophysique de Paris

M. Morales-Calderon

Centro de Astrobiologia (CAB)

Giuseppe Morello

Instituto de Astrofísica de Canarias

Spanish National Research Council (CSIC)

Norio Narita

University of Tokyo

Instituto de Astrofísica de Canarias

National Institutes of Natural Sciences

J. Orell-Miquel

Instituto de Astrofísica de Canarias

University of La Laguna

H. L.M. Osborne

University College London (UCL)

European Southern Observatory (ESO)

Dinil B. Palakkatharappil

University Paris-Saclay

Viktoria Pinter

University of Craiova

Nordic Optical Telescope

S. Redfield

Wesleyan University

Howard M. Relles

Harvard-Smithsonian Center for Astrophysics

R. Schwarz

Harvard-Smithsonian Center for Astrophysics

S. Seager

Massachusetts Institute of Technology (MIT)

Avi Shporer

Massachusetts Institute of Technology (MIT)

Marek Skarka

Czech Academy of Sciences

Masaryk University

G. Srdoc

Kotizarovci Observatory

M. Stangret

Istituto nazionale di astrofisica (INAF)

Luis Thomas

Ludwig Maximilian University of Munich (LMU)

Max Planck Society

Vincent Van Eylen

University College London (UCL)

Noriharu Watanabe

University of Tokyo

J. N. Winn

Princeton University

Astrophysical Journal Letters

2041-8205 (ISSN) 2041-8213 (eISSN)

Vol. 971 2 L28

Subject Categories (SSIF 2011)

Astronomy, Astrophysics and Cosmology

DOI

10.3847/2041-8213/ad65fd

More information

Latest update

3/18/2025