J/A+A/707/A238 TOI-2431 RV and flux curves (Tas+, 2026)
An Earth-sized planet in a 5.4h orbit around a nearby K dwarf.
Tas K.H., Stefansson G., Fariz S.N.M., Garg E., Espinoza-Retamal J.I.,
Koo E., Bruijne D., Luhn J.K., Ford E.B., Mahadevan S., Logsdon S.E.,
Canas C.I., Han T., Everett M.E., Alvarado-Montes J.A., Blake C.,
Cochran W.D., Dong J., Fernandes R.B., Giovinazzi M.R., Halverson S.,
Kanodia S., Krolikowski D., McElwain M., Ninan J., Paredes L.A.,
Robertson P., Schwab C.
<Astron. Astrophys. 707, A238 (2026)>
=2026A&A...707A.238T 2026A&A...707A.238T (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Stars, K-type ;
Photometry ; Optical
Keywords: techniques: photometric - techniques: radial velocities -
planets and satellites: detection - planets and satellites: general -
planets and satellites: terrestrial planets
Abstract:
We present the discovery and confirmation of the ultra-short period
(USP) planet TOI-2431 b orbiting a nearby (d∼36pc) late K star
(Teff=4109±28K) using observations from the Transiting Exoplanet
Survey Satellite (TESS), precise radial velocities with the NEID and
the Habitable-zone Planet Finder (HPF) spectrographs, as well as
ground-based high contrast imaging from NESSI. TOI-2431 b has a period
of 5 hours and 22 minutes, making it one of the shortest-period
exoplanets known to date. TOI-2431 b has a radius of 1.536±0.033Re,
and a mass of 6.2±1.2Me, suggesting it has a density compatible with
an Earth-like composition and, due to its high irradiation, is likely
a 'lava-world' with a Teq=2063±30K. We estimate that the current
orbital period is only 30% larger than the Roche-limit orbital period,
and that it has an expected orbital decay timescale of only ∼31Myr.
Finally, due to the brightness of the host star (V=10.9, K=7.6),
TOI-2431 b has a high Emission Spectroscopy Metric of 27, making it
one of the best USP systems for atmospheric phase-curve analysis.
Description:
Host star TOI-2431's radial velocity measurements obtained with the
NEID and HPF spectrographs, as well as the TESS photometric time
series used for the transit analysis.
Objects:
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RA (2000) DE Designation(s)
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02 31 03.28 +08 22 55.1 TOI-2431 = HIP 11707
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
rv_data.dat 37 15 Radial velocity data from NEID and HPF (table B1)
lc_data.dat 42 73522 Transit data from TESS
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Byte-by-byte Description of file: rv_data.dat
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Bytes Format Units Label Explanations
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1- 14 F14.6 d Time Barycentric Julian Date (TDB)
18- 22 F5.1 m/s RV Radial Velocity
27- 30 F4.1 m/s e_RV Uncertainty of Radial Velocity
32- 35 A4 --- Inst Instrument name (NEID or HPF)
37 A1 --- FCO [Y/N] Used in FCO analysis
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Byte-by-byte Description of file: lc_data.dat
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Bytes Format Units Label Explanations
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3- 18 F16.8 d Time Time of Observation (BJD_TDB)
21- 28 F8.6 --- Flux Normalized flux
35- 42 F8.6 --- e_Flux Uncertainty of normalized flux
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Acknowledgements:
Kaya Han Tas, kayahantas07(at)gmail.com
(End) Patricia Vannier [CDS] 26-Dec-2025