J/A+A/705/A243 GJ 4274 time series (Charpentier+, 2026)
SPIRou detects two planets around the nearby M4.5V star GJ 4274.
Charpentier P., Moutou C., Donati J.-F., Larue P., Delfosse X.,
Cortes-Zuleta P., Ould-Elhkim M., Artigau E., Cadieux C., Hebrard G.,
L'Heureux A., Carmona A., Debras F., Boisse I., Cook N.J.,
the SPIRou science Consortium
<Astron. Astrophys. 705, A243 (2026)>
=2026A&A...705A.243C 2026A&A...705A.243C (SIMBAD/NED BibCode)
ADC_Keywords: Stars, nearby ; Radial velocities ; Spectroscopy ; Magnetic fields
Keywords: techniques: radial velocities - techniques: spectroscopy
Abstract:
M dwarfs are prime targets in the search for exoplanets due to their
prevalence and the enhanced radial velocity (RV) detectability of
low-mass planets. Recent advancements in instrumentation have extended
RV observations from the optical to the near-infrared (nIR) domain,
enabling more effective study of M dwarfs, which are known to
frequently host rocky planets. The nIR range offers increased RV
sensitivity and potentially reduced stellar activity signals, making
it particularly well-suited for these stars.
We analyze spectropolarimetric data of the M4.5V star GJ 4274,
acquired using the nIR spectropolarimeter SPIRou, in order to
characterize its stellar activity and search for planetary signals. We
additionally examine the TESS photometric data to search for transits
corresponding to the potential signals in the RV data.
In this study, the line-by-line framework is employed to derive the RV
signal of GJ ,4274 acquired with SPIRou, and analyze it. From the
SPIRou spectra, we also derive and analyze the longitudinal large
scale magnetic field, Bell, and the surface temperature variations,
dTemp. We combine the SPIRou RV data with some RV measurements from
CARMENES, to model possible planetary signals with both circular and
eccentric orbits. The activity is modeled with a Quasi-Periodic
Gaussian Process. We also perform injection-recovery tests to the
photometric TESS data to assess transit detectability.
We report the discovery of two exoplanets around the nearby M dwarf
star GJ 4274. Both planets are in a circular orbit with respective
periods of Pb=1.6339±0.0001 and Pc=69.6+0.3-1.1d, this second
period being located beyond the habitable zone. From their RV
semi-amplitude signals (Kb=5.10+0.70-0.67m/s and
Kc=4.11±0.64m/s), we derived their minimum masses that are
respectively mbsini=2.97+0.54-0.50M⊕ and
mcsini=8.4±1.3M⊕. TESS photometric observations rule out
most transit scenarios, including the inner planet, yielding a maximum
inclination for the planet b of $i_b <=83^○$. We do not
detect RV variations related to stellar magnetic activity in the
SPIRou time series, despite a prominent large-scale magnetic field of
up to 206+158-62G of amplitude. We derive a rotation period for
the star of 4.600+0.011-0.006d from the activity indicators.
The two planets reported belong to the super-Earth/sub-Neptune class.
GJ 4274 b has one of the shortest orbital periods among planets around
<0.2M☉ M dwarfs within 15 pc, while GJ 4274 c lies in a sparsely
populated region of the mass-period diagram. Their discovery adds to
the census of nearby planetary systems and provides promising targets
for future surveys.
Description:
Radial velocities, longitudinal magnetic field and differential
temperature time series of GJ 4274 used in the paper.
Objects:
------------------------------------------------------------------
RA (2000) DE Designation(s)
------------------------------------------------------------------
22 23 06.99 -17 36 26.3 GJ 4274 = Gaia DR3 2595284016771502080
------------------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
rv.dat 166 128 SPIRou RV and wapiti components
dtemp.dat 71 134 Differential temperature time series
bl.dat 26 124 Longitudinal magnetic field time series
--------------------------------------------------------------------------------
Byte-by-byte Description of file: rv.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 20 F20.14 d BJD Time (BJD-240000)
22- 42 F21.15 m/s RV Radial velocity
44- 62 F19.17 m/s e_RV Error on RV
64- 88 E25.19 --- V1 First wapiti component
90-114 E25.18 -- V2 Second wapiti component
116-140 E25.18 --- V3 Third wapiti component
142-166 E25.18 km/s BERV Barrycentique Earth radial velocity
--------------------------------------------------------------------------------
Byte-by-byte Description of file: dtemp.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 20 F20.14 d BJD Time (BJD-240000)
22- 46 E25.18 K dtemp Differential temperature
48- 71 E24.18 K e_dtemp Error on dtemp
--------------------------------------------------------------------------------
Byte-by-byte Description of file: bl.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 F12.7 d BJD Time (BJD-2459000)
14- 20 F7.2 gauss Bl Longitudinal magnetic field
22- 26 F5.2 gauss e_Bl Error on Bl
--------------------------------------------------------------------------------
Acknowledgements:
Paul Charpentier, p.charpentier(at)irap.omp.eu
(End) Paul Charpentier [IRAP, France], Patricia Vannier [CDS] 10-Nov-2025