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The CORALIE survey for southern extrasolar planets. XVIII. Three new massive planets and two low-mass brown dwarfs at greater than 5 AU separation

D. Ségransan, M. Marmier, S. Udry, F. Bouchy, C. Lovis, M. Mayor, F. Pepe, D. Queloz, N. C. Santos, B. Chazelas, U. Conod, J.-B Delisle, P. Figueira, H. A. C. Giles, F. Motalebi, L. D. Nielsen, H. P. Osborn, J. Rey, M. Stalport, A. Suárez Mascareño, A. H. M. J. Triaud, O. Turner, L. Weber, A. Wyttenbach

Abstract

Context. Since 1998, a planet-search around main sequence stars within 50 pc in the southern hemisphere has been underway with the CORALIE spectrograph at La Silla Observatory.

Aims. With an observing time span of more than 20 yr, the CORALIE survey is able to detect long-term trends in data with masses and separations large enough to select ideal targets for direct imaging. Detecting these giant companion candidates will allow us to start bridging the gap between radial-velocity-detected exoplanets and directly imaged planets and brown dwarfs.

Methods. Long-term precise Doppler measurements with the CORALIE spectrograph reveal radial-velocity signatures of massive planetary companions and brown dwarfs on long-period orbits. Results. In this paper, we report the discovery of new companions orbiting HD 181234, HD 13724, HD 25015, HD 92987 and HD 50499. We also report updated orbital parameters for HD 50499b, HD 92788b and HD 98649b. In addition, we confirm the recent detection of HD 92788c. The newly reported companions span a period range of 15.6–40.4 yr and a mass domain of 2.93–26.77 MJup, the latter of which straddles the nominal boundary between planets and brown dwarfs.

Conclusions. We report the detection of five new companions and updated parameters of four known extrasolar planets. We identify at least some of these companions to be promising candidates for imaging and further characterisation.

Keywords
techniques: radial velocities; planets and satellites: detection; binaries: visual; planetary systems

Astronomy and Astrophysics
Volume 625, Article Number A71, Number of pages 16
2019 May

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Instituto de Astrofísica e Ciências do Espaço Universidade do Porto Faculdade de Ciências da Universidade de Lisboa
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia