Document Type
Article
Publication Date
9-2024
Abstract
We report the spectroscopic confirmation and fundamental properties of TOI 757 b, a mini Neptune on a 17.5 d orbit transiting a bright star ( mag) discovered by the TESS mission. We acquired high precision radial velocity measurements with the HARPS, ESPRESSO, and PFS spectrographs to confirm the planet detection and determine its mass. We also acquired space borne transit photometry with the CHEOPS space telescope to place stronger constraints on the planet radius, supported with ground based LCOGT photometry. WASP and KELT photometry were used to help constrain the stellar rotation period. We also determined the fundamental parameters of the host star. We find that TOI 757 b has a radius of and a mass of , implying a bulk density of g cm . Our internal composition modelling was unable to constrain the composition of TOI 757 b, highlighting the importance of atmospheric observations for the system. We also find the planet to be highly eccentric with e = 0.39 , making it one of the very few highly eccentric planets among precisely characterized mini Neptunes. Based on comparisons to other similar eccentric systems, we find a likely scenario for TOI 757 b’s formation to be high eccentricity migration due to a distant outer companion. We additionally propose the possibility of a more intrinsic explanation for the high eccentricity due to star star interactions during the earlier epoch of the Galactic disc formation, given the low metallicity and older age of TOI 757.
Recommended Citation
Alqasim, Ahlam, Nolan Grieves, N. M. Rosário, Davide Gandolfi, John H. Livingston, Sérgio Sousa, Karen A. Collins et al. "TOI–757 b: an eccentric transiting mini–Neptune on a 17.5–d orbit." Monthly Notices of the Royal Astronomical Society 533, no. 1 (2024): 1-26. https://doi.org/10.1093/mnras/stae1767
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Publication Title
Monthly Notices of the Royal Astronomical Society
DOI
https://doi.org/10.1093/mnras/stae1767
Comments
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