Combining TTVs, RVs, and astrometry to characterize distant giant companions of transiting hot Jupiters: Application to WASP-4
Authors: J. -V. Harre, Louise D. Nielsen, A. M. S. Smith
Abstract
The origins and architectures of hot Jupiter (HJ) systems remain unclear, with potential explanations for the tight orbits being in-situ formation, disk-migration, or high-eccentricity migration. These mechanisms can leave different imprints on the orbital architecture, but tidal interactions act to erase these imprints for HJs, leading to orbital circularization, realignment, and potentially orbital decay. The latter can be mimicked by the introduction of light travel-time effects (LTTE) caused by an outer giant companion, as for WASP-4$\,$b. We examine the WASP-4 system using newly obtained ESO$\,$3.6/HARPS radial velocity (RV) observations and archival transit-timing data, leveraging the LTTE. Furthermore, we present a novel approach of analyzing HJ systems in sight of $\textit{Gaia}$'s Data Release 4. We propose combining RV, transit-timing, and astrometry data, making use of the LTTE as a proxy for the orbital motion of a possible outer companion. We combine and fit all currently available data and simulate $\textit{Gaia}$ DR4 and DR5 astrometric measurements of WASP-4 and perform an injection and recovery procedure to estimate their impact on the recovered planetary parameters of WASP-4$\,$c. The procedure employs a combined model that describes RVs, transit timing variations (TTVs) via the LTTE, and astrometry simultaneously. Analyzing the existing data, we improve the planetary parameters of WASP-4$\,$c, finding a minimum mass of $9.3\pm1.7\,M_\mathrm{Jup}$ with an orbital period of $10\,600^{+1100}_{-1000}\,$d, or about $29\,$yr. Furthermore, we find that there is no significant orbital decay taking place for WASP-4$\,$b. In simulations of $\textit{Gaia}$ DR5, our three-pronged approach reduces the error bars of WASP-4$\,$c's parameters by about $10\%$, $25\%$, and $33\%$ for its orbital period, time of inferior conjunction, and RV semi-amplitude, respectively. (abridged)
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The CORALIE survey characterizes outer giant companions across hot-Jupiter systems, while this paper combines timing, radial velocities, and astrometry for WASP-4.
Abstract
Hot Jupiters are thought to form through multiple pathways, some of which can leave observable signatures in the architecture of their planetary systems. Massive outer companions, in particular, can provide important constraints on the dynamical histories of hot Jupiters. We aim to characterize the occurrence rate and orbital properties of additional giant companions in hot Jupiter systems, and to investigate whether these companions provide evidence for the role of dynamical interactions in shaping the hot Jupiter population. We perform a homogeneous long-term radial-velocity analysis of 147 WASP hot Jupiter systems observed with the CORALIE spectrograph between 2007 and 2025. We identify o…
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Abstract
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Abstract
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Abstract
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In short
Partial-eclipse mapping detects latitudinal brightness structure on WD 1202 B, but its recovered hotspot differs from circulation predictions, whose jet signature requires roughly threefold higher signal-to-noise.
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Abstract
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The V1298 Tau analysis combines transit and radial-velocity data to constrain young planets’ masses, while this paper studies a distant companion and possible orbital decay.
Abstract
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The TOI-2076 study resolves period ambiguities for young transiting sub-Neptunes, whereas this paper uses timing, radial velocities, and astrometry to characterize a distant giant companion.
Abstract
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