Projects per year
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 (V = 9.7 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 Rp = 2.5 ± 0.1 R⊕ and a mass of Mp = 10.5+2.2-2.1 M⊕, implying a bulk density of ρp = 3.6 ± 0.8 g cm-3. 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+0.08-0.07, 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.
| Original language | English |
|---|---|
| Article number | stae1767 |
| Number of pages | 26 |
| Journal | Monthly Notices of the Royal Astronomical Society |
| Volume | 533 |
| Issue number | 1 |
| Early online date | 31 Jul 2024 |
| DOIs | |
| Publication status | Published - 1 Sept 2024 |
Keywords
- Techniques: photometric
- Techniques: radial velocities
- Planets and satellites: composition
- Planets and satellites: interiors
- Stars: individual: TOI-757 (TIC 130924120)
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- 4 Finished
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AO2 - Professor Andrew Cameron: Project AO2 - Andrew Cameron
Cameron, A. (PI)
Science & Technology Facilities Council
1/04/21 → 31/03/24
Project: Standard
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H2020 MSCA ITN EJD 2019: H2020 MSCA ITN EJD 2019 CHAMELEON
Helling, C. (PI)
Joint Research Centre European Commission
1/06/20 → 31/05/24
Project: Standard
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Astronomy at St Andrews 2018-2021: Astronomy at St Andrews 2018-2021
Jardine, M. (PI), Bonnell, I. (CoI), Cameron, A. (CoI), Cyganowski, C. (CoI), Dominik, M. (CoI), Helling, C. (CoI), Horne, K. (CoI), Scholz, A. (CoI), Tojeiro, R. (CoI), Weijmans, A.-M. (CoI), Wild, V. (CoI), Woitke, P. (CoI), Wood, K. (CoI) & Zhao, H. (CoI)
1/04/18 → 31/03/22
Project: Standard
Datasets
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TOI–757 b: an eccentric transiting mini–Neptune on a 17.5–d orbit (dataset)
Cameron, A. C. (Creator), VizieR On-line Data Catalog, 2024
https://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/533/1
Dataset
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