A 36.34-day Sub-Neptune Candidate Transiting the Nearby K Dwarf TIC 402710280
Abstract
Transiting sub-Neptunes on orbits longer than a month are rare around bright stars. We report a candidate with a 36.34-day period around TIC 402710280, a V = 10.0 K dwarf at 66.8 pc that the Transiting Exoplanet Survey Satellite (TESS) has observed only in full-frame images. Four transits from 2021 to 2026, reduced by three independent pipelines, have consistent depths (mean 2092 ± 47 ppm) and a duration of 5.27 ± 0.05 h. Two are 36.36 days apart. The light curves exclude every shorter period consistent with both down to one day, and the duration disfavors still shorter ones, leaving P = 36.33986 ± 0.00051 d. The candidate's radius is 3.75 ± 0.22 R⊕ and its equilibrium temperature 498 ± 21 K. Difference-image centroids place the signal 1.5'' ± 1.3'' from the target, and eclipse models of the only nearby Gaia source, 3.5'' away, fit worse than a planet by Δχ2 ≥ 142 for every main-sequence pair. TRICERATOPS gives a false-positive probability of 0.003 ± 0.004; without high-resolution imaging, the object remains a candidate. The transit times scatter about a linear ephemeris by 21.8 min (rms), and an independent reduction reproduces the largest departure. Four transits cannot separate timing systematics from transit-timing variations. A second signal, of 407 ± 26 ppm at 3.78 days, may come from the target, an unresolved companion, or the background star. We predict a transit in TESS Sector 114 on 2027 February 19.
Related
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BibTeX
@misc{vora20263634day,
title = {{A 36.34-day Sub-Neptune Candidate Transiting the Nearby K Dwarf TIC 402710280}},
author = {Rishit Vora},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.26056},
eprint = {2610.26056},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.26056},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - A 36.34-day Sub-Neptune Candidate Transiting the Nearby K Dwarf TIC 402710280
AU - Rishit Vora
PY - 2026
DA - 2026/10/22
PB - arXiv
DO - 10.48550/arxiv.2610.26056
UR - https://arxiv.org/abs/2610.26056
AB - Transiting sub-Neptunes on orbits longer than a month are rare around bright stars. We report a candidate with a 36.34-day period around TIC 402710280, a V = 10.0 K dwarf at 66.8 pc that the Transiting Exoplanet Survey Satellite (TESS) has observed only in full-frame images. Four transits from 2021 to 2026, reduced by three independent pipelines, have consistent depths (mean 2092 ± 47 ppm) and a duration of 5.27 ± 0.05 h. Two are 36.36 days apart. The light curves exclude every shorter period consistent with both down to one day, and the duration disfavors still shorter ones, leaving P = 36.33986 ± 0.00051 d. The candidate's radius is 3.75 ± 0.22 R_⊕ and its equilibrium temperature 498 ± 21 K. Difference-image centroids place the signal 1.5'' ± 1.3'' from the target, and eclipse models of the only nearby Gaia source, 3.5'' away, fit worse than a planet by Δχ^2 ≥ 142 for every main-sequence pair. TRICERATOPS gives a false-positive probability of 0.003 ± 0.004; without high-resolution imaging, the object remains a candidate. The transit times scatter about a linear ephemeris by 21.8 min (rms), and an independent reduction reproduces the largest departure. Four transits cannot separate timing systematics from transit-timing variations. A second signal, of 407 ± 26 ppm at 3.78 days, may come from the target, an unresolved companion, or the background star. We predict a transit in TESS Sector 114 on 2027 February 19.
ER -