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Evidence of apsidal motion and a possible co-moving companion star detected in the WASP-19 system

Bernabo, Lia Marta and Csizmadia, Szilard and Smith, Alexis M S and Rauer, Heike and Hatzes, Artie and Esposito, Massimiliano and Gandolfi, Davide and Cabrera, J (2024) Evidence of apsidal motion and a possible co-moving companion star detected in the WASP-19 system. Astronomy & Astrophysics, 684, A78. EDP Sciences. doi: 10.1051/0004-6361/202346852. ISSN 0004-6361.

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Official URL: https://www.aanda.org/articles/aa/full_html/2024/04/aa46852-23/aa46852-23.html

Abstract

Context. Love numbers measure the reaction of a celestial body to perturbing forces, such as the centrifugal force caused by rotation, or tidal forces resulting from the interaction with a companion body. These parameters are related to the interior density profile. The non-point mass nature of the host star and a planet orbiting around each other contributes to the periastron precession. The rate of this precession is characterized mainly by the second-order Love number, which offers an opportunity to determine its value. When it is known, the planetary interior structure can be studied with one additional constraint beyond the mass, radius, and orbital parameters. Aims. We aim to re-determine the orbital period, eccentricity, and argument of the periastron for WASP-19Ab, along with a study of its periastron precession rate. We calculated the planetary Love number from the observed periastron precession rate, based on the assumption of the stellar Love number from stellar evolutionary models. Methods. We collected all available radial velocity (RV) data, along with the transit and occultation times from the previous investigations of the system. We supplemented the data set with 19 new RV data points of the host star WASP-19A obtained by HARPS. Here, we summarize the technique for modeling the RV observations and the photometric transit timing variations (TTVs) to determine the rate of periastron precession in this system for the first time. Results. We excluded the presence of a second possible planet up to a period of ~4200 d and with a radial velocity amplitude bigger than ≃ 1 m s−1. We show that a constant period is not able to reproduce the observed radial velocities. We also investigated and excluded the possibility of tidal decay and long-term acceleration in the system. However, the inclusion of a small periastron precession term did indeed improve the quality of the fit. We measured the periastron precession rate to be 233−35+25″d−1. By assuming synchronous rotation for the planet, it indicates a k2 Love number of 0.20−0.03+0.02 for WASP-19Ab. Conclusions. The derived k2,p value of the planet has the same order of magnitude as the estimated fluid Love number of other Jupiter-sized exoplanets (WASP-18Ab, WASP-103b, and WASP-121b). A low value of k2,p indicates a higher concentration of mass toward the planetary nucleus.

Item URL in elib:https://elib.dlr.de/203689/
Document Type:Article
Title:Evidence of apsidal motion and a possible co-moving companion star detected in the WASP-19 system
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Bernabo, Lia MartaUNSPECIFIEDhttps://orcid.org/0000-0002-8035-1032UNSPECIFIED
Csizmadia, SzilardUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Smith, Alexis M SUNSPECIFIEDhttps://orcid.org/0000-0002-2386-4341UNSPECIFIED
Rauer, HeikeUNSPECIFIEDhttps://orcid.org/0000-0002-6510-1828UNSPECIFIED
Hatzes, ArtieThürigner LandessternwarteUNSPECIFIEDUNSPECIFIED
Esposito, MassimilianoThuringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenberg, GermanyUNSPECIFIEDUNSPECIFIED
Gandolfi, DavideDipartimento di Fisica, Universita degli Studi di Torino, via Pietro Giuria 1, I-10125, Torino, Italy ); 0000-0001-8627-9628UNSPECIFIEDUNSPECIFIED
Cabrera, JUNSPECIFIEDhttps://orcid.org/0000-0001-6653-5487UNSPECIFIED
Date:5 April 2024
Journal or Publication Title:Astronomy & Astrophysics
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:684
DOI:10.1051/0004-6361/202346852
Page Range:A78
Publisher:EDP Sciences
ISSN:0004-6361
Status:Published
Keywords:planets and satellites: dynamical evolution and stability / planets and satellites: interiors / planet-star interactions
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Exploration
DLR - Research area:Raumfahrt
DLR - Program:R EW - Space Exploration
DLR - Research theme (Project):R - Project PLATO - PMC and Science
Location: Berlin-Adlershof
Institutes and Institutions:Institute of Planetary Research > Extrasolar Planets and Atmospheres
Institute of Planetary Research > Leitungsbereich PF
Deposited By: Bernabo, Lia Marta
Deposited On:17 Apr 2024 08:10
Last Modified:17 Apr 2024 08:10

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