Discovery of an inflated hot Jupiter around a slightly evolved star TOI-1789
Journal article, 2022

We report here the discovery of a hot Jupiter at an orbital period of 3.208664 ± 0.000015 d around TOI-1789 (TYC 1962-00303-1, TESSmag = 9.1) based on the TESS photometry, ground-based photometry, and high-precision radial velocity (RV) observations. The high-precision RV observations were obtained from the high-resolution spectrographs, PARAS at Physical Research Laboratory (PRL), India, and TCES at Thüringer Landessternwarte Tautenburg (TLS), Germany, and the ground-based transit observations were obtained using the 0.43-m telescope at PRL with the Bessel-R filter. The host star is a slightly evolved (log g∗ = 3.943+0.023-0.043), late F-type (Teff= 5991 ± 55 K), metal-rich star ([Fe/H] = 0.373+0.071-0.086 dex) with a radius of R ∗ = 2.168+0.036}-0.034 R located at a distance of 223.53+0.91-0.90} pc. The simultaneous fitting of the multiple light curves and the RV data of TOI-1789 reveals that TOI-1789 b has a mass of MP = 0.70 ± 0.16 MJ, a radius of RP = 1.44+0.24-0.14, RJ, and a bulk density of ρP = 0.28+0.14-0.12 g cm-3 with an orbital separation of a = 0.04882+0.00063-0.0016 au. This puts TOI-1789 b in the category of inflated hot Jupiters. It is one of the few nearby evolved stars with a close-in planet. The detection of such systems will contribute to our understanding of mechanisms responsible for inflation in hot Jupiters and also provide an opportunity to understand the evolution of planets around stars leaving the main-sequence branch.

techniques: radial velocities

techniques: photometric

planets and satellites: detection

stars: individual: TOI-1789-planetary system


Akanksha Khandelwal

Physical Research Laboratory

Indian Institute of Technology Gandhinagar

Priyanka Chaturvedi

Thüringer Landessternwarte Tautenburg

Abhijit Chakraborty

Physical Research Laboratory

Rishikesh Sharma

Physical Research Laboratory

Eike W. Guenther

Thüringer Landessternwarte Tautenburg

Carina Persson

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics

Malcolm Fridlund

Leiden University

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics

A. Hatzes

Thüringer Landessternwarte Tautenburg

Neelam J.S.S.V. Prasad

Physical Research Laboratory

Massimiliano Esposito

Thüringer Landessternwarte Tautenburg

Sireesha Chamarthi

Thüringer Landessternwarte Tautenburg

German Aerospace Center (DLR)

Ashirbad Nayak

Physical Research Laboratory

D. Dishendra

Physical Research Laboratory

Steve B. Howell

NASA Ames Research Center

Monthly Notices of the Royal Astronomical Society

0035-8711 (ISSN) 1365-2966 (eISSN)

Vol. 509 3 3339-3354

Subject Categories

Evolutionary Biology

Astronomy, Astrophysics and Cosmology




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1/4/2022 1