HD 83443c: A Highly Eccentric Giant Planet on a 22 yr Orbit

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• Wittenmyer, Robert A.
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• Horner, Jonathan
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• Li, Zhexing
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• Brandt, G. Mirek
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• Kane, Stephen R.
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• Fetherolf, Tara
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• Holt, Timothy R.
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• Carter, Brad
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• Clark, Jake T.
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• Butler, R. P.
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• Tinney, C. G.
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• Ballard, Sarah
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• Bowler, Brendan P.
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• Kielkopf, John
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• Liu, Huigen
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• Plavchan, Peter P.
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• Shporer, Avi
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• Zhang, Hui
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• Wright, Duncan J.
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• Addison, Brett C.
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• Mengel, Matthew W.
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• Okumura, Jack

Abstract

We report the discovery of a highly eccentric long-period Jovian planet orbiting the hot-Jupiter host HD 83443. By combining radial velocity data from four instruments (AAT/UCLES, Keck/HIRES, HARPS, Minerva-Australis) spanning more than two decades, we find evidence for a planet with m sin $i={1.35}_{-0.06}^{+0.07}$ M _J, moving on an orbit with a = 8.0 ± 0.8 au and eccentricity e = 0.76 ± 0.05. We combine our radial velocity analysis with Gaia eDR3 /Hipparcos proper motion anomalies and derive a dynamical mass of ${1.5}_{-0.2}^{+0.5}{M}_{\mathrm{Jup}}$ . We perform a detailed dynamical simulation that reveals locations of stability within the system that may harbor additional planets, including stable regions within the habitable zone of the host star. HD 83443 is a rare example of a system hosting a hot Jupiter and an exterior planetary companion. The high eccentricity of HD 83443c suggests that a scattering event may have sent the hot Jupiter to its close orbit while leaving the outer planet on a wide and eccentric path.