J/A+A/712/A142 TOI-4409 b TESS light curves (Reller+, 2026)
Confirmation of the long-period exoplanet TOI-4409 b.
Reller P., Brahm R., Merin B., Waldmann I., Trifonov T., Standing M.R.,
Vojtekova A., Guenther M., Guillot T., Stassun K.G., del Burgo C.,
Heras A.M., Lueftinger T., Triaud A.H.M.J., Isaak K., Dransfield G.,
Crouzet N., Pala A.F., Abe L., Mekarnia D., Schmider F.-X., Suarez O.,
Bendjoya P., Agabi A., Mura D., Gasparetto T., Buttu M., Eberhardt J.,
Henning T., Hobson M.J., Jordan A., Rojas F.I., Tala Pinto M., Teske J.,
Butler R.P., Crane J.D., Shectman S., Osip D., Boyle G., Leiva R., Suc V.,
Bakos G.A., Bhatti W., Hartman J.D., Csubry Z., Collins K.A., Watkins C.N.,
Schwarz R.P., Relles H.M., Srdoc G., Tan T.-G., Ziegler C.
<Astron. Astrophys. 712, A142 (2026)>
=2026A&A...712A.142R 2026A&A...712A.142R (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Photometry ; Optical
Keywords: methods: data analysis - techniques: photometric -
techniques: radial velocities - planets and satellites: detection -
planets and satellites: fundamental parameters -
planets and satellites: individual: TOI-4409 b
Abstract:
Long-period transiting planets are essential edge-cases for
understanding exoplanet formation and evolution. Their detection is
challenging due to the infrequent nature of their transits, making
every observation of these objects very valuable.
Our goal is to confirm and further characterise the long-period
planetary candidate TOI-4409 b (initially identified by TESS) through
additional observations using the Antarctica-based ASTEP telescope,
supplemented with CHAT, OMES, LCOGT, and PEST light-curve data and
radial-velocity (RV) measurements collected with the HARPS, FEROS, and
PFS instruments.
We jointly analysed the photometric data from eight TESS, four ASTEP,
one CHAT, two OMES, four LCOGT, and one PEST light curve(s), and RV
data from the HARPS, FEROS, and PFS instruments, covering observations
from 2018 to 2024.
TOI-4409 b is a bona fide puffy warm super-Neptune exoplanet with a
planet radius of 7.44±0.19R⊕ and a mass of 0.047±0.017MJ
(3σ upper limit <0.095MJ) orbiting a low-mass main-sequence
star (effective temperature of 4928±48 K and a stellar radius of
0.720±0.018R☉) with a period of 92.49179±0.00010 days. The
integration of various observational methods and consistent transit
signals across multiple instruments confirms the planetary nature of
TOI-4409 b. The combined transit, imaging, chromaticity, and RV
evidence supports the confirmation of the planet.
With a radius of 7.44±0.19R⊕ and a low bulk density of
0.20±0.07g/cm3, TOI-4409 b occupies a sparsely populated region
of parameter space among warm, puffy super-Neptunes on long-period
orbits. The detection of candidate transit timing variations with an
∼10-minute semi-amplitude hints at the presence of an additional body
in the system. The favourable host-star brightness and extended
transit duration (∼7 hours) make TOI-4409 b a promising target for
atmospheric characterisation with JWST and Ariel.
Description:
TOI-4409 b is a long-period (P=92.49 days) transiting warm
super-Neptune around a low-mass main-sequence star (Teff=4928±48K,
R*=0.720±0.018R☉). It has a planet radius of
7.44±0.19R⊕ and a mass of 0.047±0.017MJup (3-sigma upper
limit <0.095MJup), giving a low bulk density of 0.20±0.07g/cm3.
Confirmation rests on joint analysis of TESS, ASTEP, CHAT, OMES,
LCOGT, and PEST photometry plus HARPS, FEROS, and PFS radial
velocities collected from 2018 to 2024. Candidate transit-timing
variations with a ∼10-minute semi-amplitude hint at a companion.
TESS photometric time series for the eight transit windows of TOI-4409
b observed by TESS between 2018 and 2023. Each file covers
approximately two days centred on one transit event and contains
normalised PDCSAP flux extracted from the TESS pipeline products. The
data were prepared using a transit-window extraction script that
selects a baseline window around each transit epoch. Cadences range
from 20s (sectors 31, 38) through 120 s (sectors 28, 65) to 1800s
(sectors 1, 4, 8, 11).
Objects:
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RA (2000) DE Designation(s)
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05 27 16.49 -54 56 46.2 TOI-4409 = TIC 382200986
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
t1336.dat 38 94 TESS LC, transit window near BTJD 1336
t1429.dat 38 96 TESS LC, transit window near BTJD 1429
t1521.dat 38 95 TESS LC, transit window near BTJD 1521
t1614.dat 38 93 TESS LC, transit window near BTJD 1614
t2076.dat 38 1727 TESS LC, transit window near BTJD 2076
t2169.dat 38 10367 TESS LC, transit window near BTJD 2169
t2354.dat 38 10314 TESS LC, transit window near BTJD 2354
t3094.dat 38 1440 TESS LC, transit window near BTJD 3094
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Byte-by-byte Description of file: t*.dat
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Bytes Format Units Label Explanations
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1- 10 F10.5 d BJD [1335.42/3094.76] Mid-exposure time, TDB
(BJD-2457000) (1)
12- 23 F12.10 --- Flux [0.964/1.033] Normalised PDCSAP flux (2)
25- 38 F14.12 --- e_Flux [0.0006/0.0111] Per-cadence flux uncertainty
(1-sigma) (3)
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Note (1): Barycentric TESS Julian Date, defined as BJDTDB-2457000.0,
following the native TESS pipeline convention.
To recover full BJD, add 2457000.0 to the BTJD values.
Note (2): Flux is normalised Pre-search Data Conditioning Simple
Aperture Photometry (PDCSAP) flux from the TESS Science Processing
Operations Centre (SPOC) pipeline. Nominal out-of-transit level
is 1.0. Transit events produce dips of approximately 0.01 (1%).
Note (3): The eight files correspond to eight observed transits of
TOI-4409 b across TESS sectors 1, 4, 8, 11, 28, 31, 38, and 65.
File naming encodes the approximate BTJD of the transit midpoint.
Cadence varies: 1800 s (sectors 1, 4, 8, 11), 120 s
(sectors 28, 65), and 20 s (sectors 31, 38).
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Acknowledgements:
From Patricio Rellerm patricio.reller(at)ucl.ac.uk
This work uses data from the Transiting Exoplanet Survey Satellite
(TESS) mission, obtained from the Mikulski Archive for Space
Telescopes (MAST) at STScI.
License: CC-BY-4.0
References:
Ricker et al., TESS, 2015JATIS...1a4003R 2015JATIS...1a4003R
Jenkins et al., SPOC pipeline, 2016SPIE.9913E..3EJ
(End) Patricio Reller [UCL/ESA], Patricia Vannier [CDS] 26-May-2026