_version_ 1866911477367046144
author García-Mejía, Juliana
de Beurs, Zoë L.
Tamburo, Patrick
Vanderburg, Andrew
Charbonneau, David
Collins, Karen A.
Barkaoui, Khalid
Watkins, Cristilyn N.
Stockdale, Chris
Schwarz, Richard P.
Forés-Toribio, Raquel
Muñoz, Jose A.
Isopi, Giovanni
Mallia, Franco
Zapparata, Aldo
Popowicz, Adam
Brudny, Andrzej
Agol, Eric
Alam, Munazza K.
Benkhaldoun, Zouhair
Emmanuel, Jehin
Ghachoui, Mourad
Gillon, Michaël
Horne, Keith
Pallé, Enric
Sefako, Ramotholo
Shporer, Avi
Timmermans, Mathilde
author_facet García-Mejía, Juliana
de Beurs, Zoë L.
Tamburo, Patrick
Vanderburg, Andrew
Charbonneau, David
Collins, Karen A.
Barkaoui, Khalid
Watkins, Cristilyn N.
Stockdale, Chris
Schwarz, Richard P.
Forés-Toribio, Raquel
Muñoz, Jose A.
Isopi, Giovanni
Mallia, Franco
Zapparata, Aldo
Popowicz, Adam
Brudny, Andrzej
Agol, Eric
Alam, Munazza K.
Benkhaldoun, Zouhair
Emmanuel, Jehin
Ghachoui, Mourad
Gillon, Michaël
Horne, Keith
Pallé, Enric
Sefako, Ramotholo
Shporer, Avi
Timmermans, Mathilde
contents We present a ground-based transit detection of HIP 41378 f, a long-period ($P = 542$ days), extremely low-density ($0.09 \pm 0.02$ g cm$^{-3}$) giant exoplanet in a dynamically complex system. Using photometry from Tierras, TRAPPIST-North, and multiple LCOGT sites, we constrain the transit center time to $T_{C,6} = 2460438.891 \pm 0.052$ BJD TDB. This marks only the second ground-based detection of HIP 41378 f, currently the longest-period and longest-duration transiting exoplanet observed from the ground. We use this new detection, along with a recently published transit time from Rossiter-McLaughlin observations, to update the TTV solution for HIP 41378 f. We predict the next two transits will occur at $T_{C,7} = 2460980.793^{+0.098}_{-0.129}$ BJD TDB (2025 November 1) and $T_{C,8} = 2461522.653^{+0.213}_{-0.238}$ BJD TDB (2027 April 27). Incorporating new TESS Sector 88 data, we also rule out the 101-day orbital period alias for HIP 41378 d, and find that the remaining viable solutions are centered on the 278, 371, and 1113-day aliases. The latter two imply dynamical configurations that challenge the canonical view of planet e as the dominant perturber of planet f. Our results suggest that HIP 41378 d may instead play the leading role in shaping the TTV of HIP 41378 f.
format Preprint
id arxiv_https___arxiv_org_abs_2506_20907
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A Ground-Based Transit Observation of the Long-Period Extremely Low-Density Planet HIP 41378 f
García-Mejía, Juliana
de Beurs, Zoë L.
Tamburo, Patrick
Vanderburg, Andrew
Charbonneau, David
Collins, Karen A.
Barkaoui, Khalid
Watkins, Cristilyn N.
Stockdale, Chris
Schwarz, Richard P.
Forés-Toribio, Raquel
Muñoz, Jose A.
Isopi, Giovanni
Mallia, Franco
Zapparata, Aldo
Popowicz, Adam
Brudny, Andrzej
Agol, Eric
Alam, Munazza K.
Benkhaldoun, Zouhair
Emmanuel, Jehin
Ghachoui, Mourad
Gillon, Michaël
Horne, Keith
Pallé, Enric
Sefako, Ramotholo
Shporer, Avi
Timmermans, Mathilde
Earth and Planetary Astrophysics
We present a ground-based transit detection of HIP 41378 f, a long-period ($P = 542$ days), extremely low-density ($0.09 \pm 0.02$ g cm$^{-3}$) giant exoplanet in a dynamically complex system. Using photometry from Tierras, TRAPPIST-North, and multiple LCOGT sites, we constrain the transit center time to $T_{C,6} = 2460438.891 \pm 0.052$ BJD TDB. This marks only the second ground-based detection of HIP 41378 f, currently the longest-period and longest-duration transiting exoplanet observed from the ground. We use this new detection, along with a recently published transit time from Rossiter-McLaughlin observations, to update the TTV solution for HIP 41378 f. We predict the next two transits will occur at $T_{C,7} = 2460980.793^{+0.098}_{-0.129}$ BJD TDB (2025 November 1) and $T_{C,8} = 2461522.653^{+0.213}_{-0.238}$ BJD TDB (2027 April 27). Incorporating new TESS Sector 88 data, we also rule out the 101-day orbital period alias for HIP 41378 d, and find that the remaining viable solutions are centered on the 278, 371, and 1113-day aliases. The latter two imply dynamical configurations that challenge the canonical view of planet e as the dominant perturber of planet f. Our results suggest that HIP 41378 d may instead play the leading role in shaping the TTV of HIP 41378 f.
title A Ground-Based Transit Observation of the Long-Period Extremely Low-Density Planet HIP 41378 f
topic Earth and Planetary Astrophysics
url https://arxiv.org/abs/2506.20907