* Astronomy

Title: The Anglo-Australian Planet Search. XXII. Two New Multi-Planet Systems
Authors: Robert A. Wittenyer, J. Horner, M. Tuomi, G. S. Salter, C. G. Tinney, R. P. Butler, H. R. A. Jones, S. J. O'Toole, J. Bailey, B. D. Carter, J. S. Jenkins, Z. Zhang, S. S. Vogt, E. J. Rivera

We report the detection of two new planets from the Anglo-Australian Planet Search. These planets orbit two stars each previously known to host one planet. The new planet orbiting HD 142 has a period of 6005 ±427 days, and a minimum mass of 5.3M_Jup. HD142c is thus a new Jupiter analogue: a gas-giant planet with a long period and low eccentricity (e = 0.21 ±0.07). The second planet in the HD 159868 system has a period of 352.3 ±1.3 days, and m sin i=0.73 ±0.05 Jupiter masses. In both of these systems, including the additional planets in the fitting process significantly reduced the eccentricity of the original planet. These systems are thus examples of how multiple-planet systems can masquerade as moderately eccentric single-planet systems.

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