J/A+A/707/A73 TOI-3288 A b and TOI-4666 b light and RV curves (Frensch+, 2026)
TOI-3288 A b and TOI-4666 b: Two gas giants transiting low-mass stars
characterised by NIRPS.
Frensch Y.G.C., Bouchy F., Lo Curto G., L'Heureux A., de Lima Gomes R.,
Faria J., Dumusque X., Malo L., Cointepas M., Srivastava A., Bonfils X.,
Delgado-Mena E., Nari N., Artigau E., Baron F., Barros S.C.C., Benneke B.,
Bryan M., Canto Martins B.L., de Castro Leao I., Cloutier R., Cook N.J.,
Cowan N.B., Cristo E., De Medeiros J.R., Delfosse X., Doyon R.,
Ehrenreich D., Gonzalez Hernandez J.I., Lafreniere D., Lovis C., Melo C.,
Mignon L., Mordasini C., Pepe F., Rebolo R., Rowe J., Santos N.C.,
Segransan D., Suarez Mascareno A., Udry S., Valencia D., Wade G.,
Al Moulla K., Allart R., Almenara J.M., Barkaoui K., Cadieux C.,
Castro-Gonzalez A., Collins K.A., Fajardo-Acosta S.B., Forveille T., Gan T.,
Gomes da Silva J., Grieves N., Hobson M.J., Howell S., Lamontagne P.,
Messamah L., Nielsen L.D., Osborn A., Parc L., Piaulet-Ghorayeb C.,
Stassun K.G., Stefanov A.K., Striegel S., Ulmer-Moll S., Vaulato V.,
Watkins C.N.
<Astron. Astrophys. 707, A73 (2026)>
=2026A&A...707A..73F 2026A&A...707A..73F (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Stars, M-type ;
Photometry ; Optical ; Radial velocities ; Spectra, infrared
Keywords: techniques: photometric - techniques: radial velocities -
planets and satellites: gaseous planets -
stars: individual: TOI-3288 - stars: individual: TOI-4666
Abstract:
Gas giant planets orbiting low-mass stars (Teff≤4600K) are uncommon
outcomes of planet formation. Increasing the sample of
well-characterised giants around early M dwarfs will enable
population-level studies of their properties, offering valuable
insights into their formation and evolutionary histories.
We aim to confirm and characterise giant exoplanets transiting M
dwarfs identified by the TESS mission. To this end, we have started
the Gas giAnts Transiting lOw-mass Stars (GATOS) program within the
NIRPS Guaranteed Time Observations (GTO).
High-resolution spectroscopic data are obtained in the optical and
near-infrared (nIR), combining HARPS and NIRPS. We derive radial
velocities (RVs) via the cross-correlation function and implement a
novel post-processing procedure to further mitigate telluric
contamination in the nIR. The resulting RVs are jointly fit with TESS
and ground-based photometry to derive the orbital and physical
parameters of the systems.
We present the GATOS program and its first results. We confirm two gas
giants transiting the low-mass stars TOI-3288 A (K9V, Teff=3933±48K)
and TOI-4666 (M2.5V, Teff=3512±36K). TOI-3288 A hosts a hot Jupiter
with a mass of 2.11±0.08MJup and a radius of 1.00±0.03RJup,
with an orbital period of 1.43 days (Teq=1059±20K). TOI-4666 hosts a
0.70±0.06MJup warm Jupiter (Teq=713±14K) with a radius of
1.11±0.04RJup, with an orbital period of 2.91 days. At a
population level, we identify a decrease in planetary mass with
spectral type, where late M dwarfs host less massive giant planets
than early M dwarfs. More massive gas giants that deviate from this
trend are preferentially hosted by more metal-rich stars. Furthermore,
we find an increased binarity fraction among low-mass stars hosting
gas giants, which may play a role in enhancing giant planet formation
around low-mass stars.
These mass characterizations contribute to the growing catalogue of
well-defined giant exoplanets around low-mass stars. The observed
population trends agree with theoretical predictions, where higher
metallicity can compensate for lower disk masses, and wide binary
systems may influence planet formation and migration through
Kozai-Lidov cycles or disk instabilities.
Description:
Photometry and radial velocities used to confirm the planetary nature
of TOI-3288 A b and TOI-4666 b.
Objects:
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RA (2000) DE Designation(s)
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19 48 26.5 -43 01 04.8 TOI-3288 A = TIC 79920467
03 45 09.6 -39 03 47.5 TOI-4666 = TIC 165202476
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
toi3288l.dat 62 12741 TESS photometry of TOI-3288 A extracted with
optimized apertures to reduce contamination
(Sectors 13, 27, and 67) (table I1)
toi4666l.dat 62 3445 TESS photometry of TOI-4666 extracted with
optimized apertures to reduce contamination
(Sector 31) (table I2)
toi3288r.dat 85 45 HARPS and NIRPS radial velocities of TOI-3288 A
obtained under the NIRPS-GTO programs (PI: Bouchy)
(table H1)
toi4666r.dat 85 59 HARPS and NIRPS radial velocities of TOI-4666
obtained under the NIRPS-GTO programs (PI: Bouchy)
(table H2)
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Byte-by-byte Description of file: toi3288l.dat toi4666l.dat
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Bytes Format Units Label Explanations
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1- 18 F18.12 d BJD Reduced barycentric Julian date (BJD-2400000)
20- 37 F18.16 --- Flux TESS normalized flux
39- 59 F21.19 --- e_Flux TESS normalized flux error
61- 62 I2 --- Sector TESS Sector
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Byte-by-byte Description of file: toi3288r.dat toi4666r.dat
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Bytes Format Units Label Explanations
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1- 10 F10.4 d BJD Reduced barycentric Julian date (BJD-2400000)
12- 20 F9.3 m/s RV Radial velocity
22- 28 F7.3 m/s e_RV Radial velocity error
30- 38 F9.3 m/s FWHM Full width at half maximum (FWHM) of the
cross-correlation function (CCF)
40- 47 F8.3 m/s e_FWHM Error of the FWHM of the CCF
49- 56 F8.3 % Contrast Contrast of the CCF
58- 66 F9.3 m/s BERV Barycentric Earth radial velocity
68- 74 F7.2 s Texp Exposure time
76- 80 A5 --- Inst Spectrograph
82- 85 A4 --- Mode Observing mode
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Acknowledgements:
Yolanda Frensch, yolanda.frensch(at)astro.up.pt
(End) Yolanda Frensch [CAUP, Portugal], Patricia Vannier [CDS] 14-Jan-2026