The TESS–Keck Survey. XIII. An Eccentric Hot Neptune with a Similar-mass Outer Companion around TOI-1272
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MacDougall_2022_AJ_164_97.pdf
Description
Published version
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1.91 MB
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Adobe PDF
Checksum (MD5)
7af370150f97f56b8044f04a73ba6a24
Author(s)
Seager, Sara
Date Issued
2022
Journal
Astronomical Journal
Publisher
American Astronomical Society
Citation
Seager, Sara. 2022. "The TESS–Keck Survey. XIII. An Eccentric Hot Neptune with a Similar-mass Outer Companion around TOI-1272." Astronomical Journal, 164 (3).
Version
Final published version
Abstract
We report the discovery of an eccentric hot Neptune and a non-transiting outer planet around TOI-1272. We identified the eccentricity of the inner planet, with an orbital period of 3.3 days and Rp,b = 4.1 ± 0.2 R⊕, based on a mismatch between the observed transit duration and the expected duration for a circular orbit. Using ground-based radial velocity (RV) measurements from the HIRES instrument at the Keck Observatory, we measured the mass of TOI-1272b to be Mp,b = 25 ± 2 M⊕. We also confirmed a high eccentricity of eb = 0.34 ± 0.06, placing TOI-1272b among the most eccentric well-characterized sub-Jovians. We used these RV measurements to also identify a non-transiting outer companion on an 8.7 day orbit with a similar mass of Mp,c sin i = 27 ± 3 M⊕ and ec ≲ 0.35. Dynamically stable planet–planet interactions have likely allowed TOI-1272b to avoid tidal eccentricity decay despite the short circularization timescale expected for a close-in eccentric Neptune. TOI-1272b also maintains an envelope mass fraction of fenv ≈ 11% despite its high equilibrium temperature, implying that it may currently be undergoing photoevaporation. This planet joins a small population of short-period Neptune-like planets within the "Hot Neptune Desert" with a poorly understood formation pathway.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
Terms of Use
Creative Commons Attribution 4.0 International license
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DOI of Published Version
https://doi.org/10.3847/1538-3881/AC7CE1
