The compact multi-planet system GJ 9827 revisited with ESPRESSO

Journal
Date Issued
2024
Author(s)
Passegger, V. M.
•
Suárez Mascareño, A.
•
Allart, R.
•
González Hernández, J. I.
•
Lovis, C.
•
Lavie, B.
•
Silva, A. M.
•
Müller, H. M.
•
Tabernero, H. M.
•
•
Pepe, F.
•
Rebolo, R.
•
Santos, N. C.
•
Adibekyan, V.
•
Alibert, Y.
•
Allende Prieto, C.
•
Barros, S. C. C.
•
Bouchy, F.
•
Castro-González, A.
•
•
Dumusque, X.
•
•
Ehrenreich, D.
•
Figueira, P.
•
Génova Santos, R.
•
Lo Curto, G.
•
Martins, C. J. A. P.
•
Mehner, A.
•
•
•
Nari, N.
•
Nunes, N. J.
•
Pallé, E.
•
•
Rodrigues, J.
•
Sousa, S. G.
•
•
Udry, S.
•
Zapatero Osorio, M. R.
DOI
Abstract
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 = 4.28−0.33+0.35 M⊕, Mc = 1.86−0.39+0.37 M⊕, and Md = 3.02−0.57+0.58 M⊕, and orbital periods of 1.208974 ± 0.000001 days for planet b, 3.648103−0.000010+0.000013 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.

Extracted radial velocities from ESPRESSO and HARPS used in this work are available at the CDS via anonymous ftp to cdsarc.cds.unistra.fr (ftp://130.79.128.5), or via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/684/A22

Échelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations. Based on guaranteed time observations collected at the European Southern Observatory under ESO programme(s) 1102.C-0744, 1104.C-0350 by the ESPRESSO Consortium.

Volume
684
Start page
A22
Uri
Url
Issn Identifier
0004-6361
Ads BibCode
2024A&A...684A..22P
Rights
open.access
File(s)
Loading...
Thumbnail Image
Name

passegger_aa48592-23.pdf

Description
PDF editoriale
Size

7.06 MB

Format

Adobe PDF

Checksum (MD5)

c6993c195dd8774e00bdb7a9da6cab41