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TESS giants transiting giants V – two hot Jupiters orbiting red giant hosts

L. F. Pereira, S. K. Grunblatt, A. Psaridi, T. L. Campante, M. S. Cunha, N. C. Santos, D. Bossini, D. Thorngren, C. Hellier, F. Bouchy, M. Lendl, D. Mounzer, S. Udry, C. Beard, C. L. Brinkman, H. Isaacson, S. N. Quinn, D. Tyler, G. Zhou, S. B. Howell, A. W. Howard, J. M. Jenkins, S. Seager, R. K. Vanderspek, J. N. Winn, N. Saunders, D. Huber

In this work, we present the discovery and confirmation of two hot Jupiters orbiting red giant stars, TOI-4377 b and TOI-4551 b, observed by Transiting Exoplanet Survey Satellite in the Southern ecliptic hemisphere and later followed-up with radial-velocity (RV) observations. For TOI-4377 b, we report a mass of 0.957-0.087 MJ and a inflated radius of 1.348 ± 0.081 RJ orbiting an evolved intermediate-mass star (1.36 M⊙ and 3.52 R⊙; TIC 394918211) on a period of of 4.378 d. For TOI-4551 b, we report a mass of 1.49 ± 0.13 MJ and a radius that is not obviously inflated of 1.058-0.062+0.110 RJ⁠, also orbiting an evolved intermediate-mass star (1.31 M⊙ and 3.55 R⊙; TIC 204650483) on a period of 9.956 d. We place both planets in context of known systems with hot Jupiters orbiting evolved hosts, and note that both planets follow the observed trend of the known stellar incident flux-planetary radius relation observed for these short-period giants. Additionally, we produce planetary interior models to estimate the heating efficiency with which stellar incident flux is deposited in the planet’s interior, estimating values of 1.71 ± 0.48 per cent and 2.19 ± 0.45 per cent for TOI-4377 b and TOI-4551 b, respectively. These values are in line with the known population of hot Jupiters, including hot Jupiters orbiting main-sequence hosts, which suggests that the radii of our planets have re-inflated in step with their parent star’s brightening as they evolved into the post-main sequence. Finally, we evaluate the potential to observe orbital decay in both systems.

exoplanets, planets and satellites: detection

Monthly Notices of the Royal Astronomical Society
Volume 527, Issue 3, Page 13
2024 January

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Faculdade de Ciências da Universidade de Lisboa Universidade do Porto Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia