Evidence for an additional planet in the β Pictoris system


With its imaged debris disk of dust, its evaporating exocomets, and an imaged giant planet, the young (~23 Myr) β Pictoris system is a unique proxy for detailed studies of planet formation processes as well as planet–disk interactions. Here, we study ten years of European Southern Observatory/High Accuracy Radial Velocity Planet Searcher (HARPS) high-resolution spectroscopic data of β Pictoris. After removing the radial velocity (RV) signals arising from the δ Scuti pulsations of the star, a ~1,200-d periodic signal remains, which, within our current knowledge, we can only attribute to a second planet in the system. The β Pic c mass is about nine times the mass of Jupiter; it orbits at ~2.7 au on an eccentric (e ~ 0.24) orbit. More RV data are needed to obtain more precise estimates of the properties of β Pic c. The current modelling of the planet’s properties and the dynamic of the whole system has to be reinvestigated in light of this detection.

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Fig. 1: RV variations of β Pictoris and generalized Lomb–Scargle periodograms.
Fig. 2: Pulsation-corrected RV data with corresponding generalized Lomb–Scargle periodogram.
Fig. 3: Keplerian fits of the pulsation-corrected RV data.
Fig. 4: Properties of the additional planet.

Data availability

The HARPS spectra are available in the ESO archive, and the measured RV data are given in Supplementary Table 1.

Code availability

The codes used for this paper are available from the corresponding author upon reasonable request.


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This work has been supported by grants from the Agence Nationale de la Recherche (ANR-14-CE33–0018) and the French Labex OSUG@2020 (Investissements d’avenir—ANR10 LABX56). A.Z. was supported by CONICYT grant no. 2117053. A.-M.L. thanks F. Forbes, K. Zwincks, A. Lecavelier, J. Pepper, P. Kervella and J. C. B. Papaloizou for discussions. T.G., D.M., L.A. and F.-X.S. acknowledge support from Idex UCAJEDI (ANR-15-IDEX-01) and IPEV.

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A.-M.L. led the monitoring of the variations, the data reduction, the analysis and interpretation of the data, and the paper writing. N.M., P.R., M.K. and F.G. participated to the data fitting and analysis. E.C., E.M., L.B. and F.-X.S. brought their expertise in stellar variability. H.B. provided analysis of the dynamical stability of the system. T.G., D.M. and L.A. brought expertise on β Pictoris photometric variability. P.A.W. and F.K. brought expertise on β Pictoris spectroscopic variability. M.B., S.B., A.G., J.L.-B., B.P., D.P.I., L.R. and A.Z.S. participated in the observations.

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Correspondence to A.-M. Lagrange.

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Lagrange, A., Meunier, N., Rubini, P. et al. Evidence for an additional planet in the β Pictoris system. Nat Astron 3, 1135–1142 (2019). https://doi.org/10.1038/s41550-019-0857-1

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