J/A+A/684/A22 ESPRESSO and HARPS S-BART RVs of GJ9827 (Passegger+, 2024)
The compact multi-planet system GJ 9827 revisited with ESPRESSO.
Passegger V.M., Suarez Mascareno A., Allart R., Gonzalez Hernandez J.I.,
Lovis C., Lavie B., Silva A.M., Mueller H.M., Tabernero H.M., Cristiani S.,
Pepe F., Rebolo R., Santos N.C., Adibekyan V., Alibert Y.,
Allende Prieto C., Barros S.C.C., Bouchy F., Castro-Gonzalez A.,
D'Odorico V., Dumusque X., Di Marcantonio P., Ehrenreich D., Figueira P.,
Genova Santos R., Lo Curto G., Martins C.J.A.P., Mehner A., Micela G.,
Molaro P., Nari N., Nunes N.J., Palle E., Poretti E., Rodrigues J.,
Sousa S.G., Sozzetti A., Udry S., Zapatero Osorio M.R.
<Astron. Astrophys. 684, A22 (2024)>
=2024A&A...684A..22P 2024A&A...684A..22P (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Radial velocities ;
Optical
Keywords: methods: data analysis - planetary systems -
techniques: radial velocities - techniques: spectroscopic -
stars: fundamental parameters - stars: individual: GJ 9827
Abstract:
Deriving metallicities for solar-like stars follows well-established
GJ 9827 is a bright, nearby K7V star orbited by two super-Earths and
one mini-Neptune on close-in orbits. The system was first discovered
using K2 data and then further characterized by other spectroscopic
and photometric instruments. Previous literature studies provide
several mass measurements for the three planets, however, with large
variations and uncertainties. To better constrain the planetary
masses, we added high-precision radial velocity measurements from
ESPRESSO to published datasets from HARPS, HARPS-N, and HIRES and we
performed a Gaussian process analysis combining radial velocity and
photometric datasets from K2 and TESS. This method allowed us to model
the stellar activity signal and derive precise planetary parameters.
We determined planetary masses of Mb=4.28+0.35-0.33M⊕,
Mc=1.86+0.37-0.39M⊕, and Md=3.02+0.58-0.57M⊕,
and orbital periods of 1.208974±0.000001 days for planet b,
3.648103+0.000013-0.000010 days for planet c, and
6.201812±0.000009 days for planet d. We compared our results to
literature values and found that our derived uncertainties for the
planetary mass, period, and radial velocity amplitude are smaller than
the previously determined uncertainties. We modeled the interior
composition of the three planets using the machine-learning-based tool
ExoMDN and conclude that GJ 9827 b and c have an Earth-like
composition, whereas GJ 9827 d has an hydrogen envelope, which,
together with its density, places it in the mini-Neptune regime.
Description:
We present radial velocities for GJ 9827 observed with ESPRESSO under
program ID 1102.C-0744 and 1104.C-0350 and with HARPS under program ID
099.C-0491(A), 0100.C-0808(A), and 0101.C-0788. Radial velocities have
been extracted using the S-BART pipeline. The columns show BJD in
days, extracted radial velocity in km/s, and error in km/s.
Objects:
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RA (2000) DE Designation(s)
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23 27 04.83 -01 17 10.5 GJ 9827 = BD-02 5958
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
espresso.dat 58 54 S-BART extracted RVs from ESPRESSO
harps.dat 58 147 S-BART extracted RVs from HARPS
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See also:
J/MNRAS/484/3731 : GJ 9827 HARPS-N RV data (Rice+, 2019)
J/AJ/161/47 : RV and photometry of HD106315 and GJ9827 (Kosiarek+, 2021)
Byte-by-byte Description of file: espresso.dat harps.dat
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Bytes Format Units Label Explanations
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1- 16 F16.8 d BJD Barycentric Julian Date
20- 35 F16.13 km/s RV Radial velocity
39- 58 F20.18 km/s e_RV Error in radial velocity
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Acknowledgements:
Vera Maria Passegger, vpassegger(at)hs.uni-hamburg.de
(End) Vera Maria Passegger [IAC, Spain], Patricia Vannier [CDS] 24-Jan-2024