J/A+A/688/A196 GJ 1289 and GJ 3378 RV, B and DetlaT (Moutou+, 2024)
Characterizing planetary systems with SPIRou:
Temperate sub-Neptune exoplanet orbiting the nearby fully convective star
GJ 1289 and a candidate around GJ 3378.
Moutou C., Ould-Elhkim M., Donati J.-F., Charpentier P., Cadieux C.,
Delfosse X., Artigau E., Arnold L., Baruteau C., Carmona A., Cook N.J.,
Cortes Zuleta P., Doyon R., Hebrard G., the SLS consortium
<Astron. Astrophys. 688, A196 (2024)>
=2024A&A...688A.196M 2024A&A...688A.196M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Infrared ;
Radial velocities ; Magnetic fields
Keywords: instrumentation: spectrographs - techniques: radial velocities -
stars: magnetic field - planetary systems -
stars: individual: GJ 1289 - stars: individual: GJ 3378
Abstract:
We report the discovery of two new exoplanet systems around fully
convective stars, found from the radial-velocity (RV) variations of
their host stars measured with the nIR spectropolarimeter CFHT/SPIRou
over multiple years. GJ 3378 b is a planet with minimum mass of
5.26+0.94-0.97M⊕ on an eccentric 24.73-day orbit around an
M4V star of 0.26M☉. GJ 1289 b has a minimum mass of
6.27±1.25M⊕ in a 111.74-day orbit, on a circular orbit
around an M4.5V star of mass 0.21M☉. Both stars are in the solar
neighbourhood, at 7.73 and 8.86 pc, respectively. The low-amplitude RV
signals are detected after line-by-line post-processing treatment.
These potential sub-Neptune class planets around cool stars may have
temperate atmospheres and be interesting nearby systems for further
studies. We also recovered the large-scale magnetic field of both
stars, found to be mostly axisymmetric and dipolar, with polar
strengths of 20-30G and 200-240G for GJ 3378 (in 2019-21) and GJ 1289
(in 2022-23), respectively. The rotation periods measured with the
magnetic field differ from the orbital periods and, in general,
stellar activity is not seen in the studied nIR RV time series of both
stars. GJ 3378 b detections have not been confirmed by optical RVs
and, therefore, they are solely considered a candidate for the present
purposes.
Description:
GJ 3378 was observed with SPIRou 181 times between 18 September 2019
and 31 January 2022, over a time span of 876 days. The airmass values
range from 1.301 to 2.037. The spectrum moves within a barycentric
Earth RV (BERV) range of ±24.5km/s due to the Earth motion around
the Sun, a configuration that is favourable to getting a clean stellar
template and good performance in telluric correction (Ould-Elhkim et
al, in prep.). The average exposure time is 544s per visit and the
mean obtained signal-to-noise ratio (S/N) is 212 per pixel in the H
band. GJ 1289 was observed with SPIRou 300 times between 15 May 2019
and 25 January 2024 with a time span of 1686 days. The airmass vales
range from 1.05 to 2.54 and observations have a maximum BERV range of
±25.2km/s. Average exposure times and S/N per nightly visit are,
respectively, 800s and 200 per pixel in the H band.
Tables contain GJ 3378 and GJ 1289 relative radial velocity, magnetic
field, and differential effective temperature measured by SPIRou.
Objects:
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RA (2000) DE Designation(s)
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06 01 11.04 +59 35 49.8 GJ 3378 = TIC 322347050
23 43 06.31 +36 32 13.1 GJ 1289 = TIC 352593978
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
gj1289.dat 79 294 GJ1289 data
gj3378.dat 79 176 GJ3378 data
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Byte-by-byte Description of file: gj1289.dat gj3378.dat
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Bytes Format Units Label Explanations
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1- 10 A10 "date" Date UT date of observation
12- 22 F11.5 d BJD Barycentric Julian Date (BJD-2400000)
24- 27 I4 --- SNR SNR per pixel in the H band
29- 34 F6.2 G Bl Longitudinal magnetic field
36- 40 F5.2 G e_Bl Error on Bl
42- 47 F6.2 G N Check value N
49- 53 F5.2 G e_N Error on N
55- 60 F6.2 m/s RV ?=99.9 Radial Velocity
62- 66 F5.2 m/s e_RV ?=99.9 Error on RV
68- 73 F6.2 K dET ?=99.9 Differential effective temperature
75- 79 F5.2 K e_dET ?=99.9 Error on dET
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Acknowledgements:
Claire Moutou, claire.moutou(at)irap.omp.eu
(End) Patricia Vannier [CDS] 24-Jul-2024