A transit timing variation observed for the long-period extremely low-density exoplanet HIP 41378 f

Bryant, Edward M; Bayliss, Daniel; Santerne, Alexandre; Wheatley, Peter J; Nascimbeni, Valerio; Ducrot, Elsa; Burdanov, Artem; Acton, Jack S; Alves, Douglas R; Anderson, David R; Armstrong, David J; Awiphan, Supachai; Cooke, Benjamin F; Burleigh, Matthew R; Casewell, Sarah L; Delrez, Laetitia; Demory, Brice-Olivier; Eigmüller, Philipp; Fukui, Akihiko; Gan, Tianjun; ... (2021). A transit timing variation observed for the long-period extremely low-density exoplanet HIP 41378 f. Monthly notices of the Royal Astronomical Society - letters, 504(1), L45-L50. Oxford University Press 10.1093/mnrasl/slab037

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HIP 41378 f is a temperate 9.2 ± 0.1 R⊕ planet with period of 542.08 d and an extremely low density of 0.09 ± 0.02 g cm−3. It transits the bright star HIP 41378 (V = 8.93), making it an exciting target for atmospheric characterization including transmission spectroscopy. HIP 41378 was monitored photometrically between the dates of 2019 November 19 and 28. We detected a transit of HIP 41378 f with NGTS, just the third transit ever detected for this planet, which confirms the orbital period. This is also the first ground-based detection of a transit of HIP 41378 f. Additional ground-based photometry was also obtained and used to constrain the time of the transit. The transit was measured to occur 1.50 h earlier than predicted. We use an analytic transit timing variation (TTV) model to show the observed TTV can be explained by interactions between HIP 41378 e and HIP 41378 f. Using our TTV model, we predict the epochs of future transits of HIP 41378 f, with derived transit centres of TC, 4 = 2459355.087+0.031−0.022 (2021 May) and TC, 5 = 2459897.078+0.114−0.060 (2022 November).

Item Type:

Journal Article (Original Article)


10 Strategic Research Centers > Center for Space and Habitability (CSH)

UniBE Contributor:

Demory, Brice-Olivier Denys


500 Science > 520 Astronomy




Oxford University Press




Brice-Olivier Denys Demory

Date Deposited:

04 Apr 2022 15:14

Last Modified:

02 Mar 2023 23:36

Publisher DOI:






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