Volume 646, February 2021
|Number of page(s)||19|
|Section||Planets and planetary systems|
|Published online||19 February 2021|
European Southern Observatory, Alonso de Córdova 3107,
2 Instituto de Astronomía, Universidad Católica del Norte, Angamos 0610 1270709, Antofagasta, Chile
3 University of Southern Queensland, Centre for Astrophysics, Toowoomba, QLD 4350, Australia
4 Departamento de Ciencias Físicas Universidad Andrés Bello. Fernández Concha 700, 759-1538, Las Condes, Santiago, Chile
5 School of Physics and Astronomy, Queen Mary University, 327 Mile End Road, London E1 4NS, UK
6 Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 7820436 Macul, Santiago, Chile
7 Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
8 Departamento de Astronomía, Universidad de Chile, Camino El Observatorio 1515, Las Condes, Santiago, Chile
9 Centro de Astrofísica y Tecnologías Afines (CATA), Casilla 36-D, Santiago, Chile
10 Main Astronomical Observatory, National Academy of Sciences of the Ukraine, 03143 Kyiv, Ukraine
11 Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez, Av. Diagonal las Torres 2640, Peñalolén, Santiago, Chile
12 Millennium Institute for Astrophysics, Santiogo, Chile
13 Instituto de Física y Astronomía, Universidad de Valparaíso, Casilla 5030, Valparaíso, Chile
14 Department of Physics and Astronomy, Bucknell University, Lewisburg, PA 17837, USA
Accepted: 8 December 2020
We report the discovery of planetary companions orbiting four low-luminosity giant stars with M⋆ between 1.04 and 1.39 M⊙. All four host stars have been independently observed by the EXoPlanets aRound Evolved StarS (EXPRESS) program and the Pan-Pacific Planet Search (PPPS). The companion signals were revealed by multi-epoch precision radial velocities obtained in nearly a decade. The planetary companions exhibit orbital periods between ~1.2 and 7.1 yr, minimum masses of mpsin i ~ 1.8–3.7 MJ, and eccentricities between 0.08 and 0.42. With these four new systems, we have detected planetary companions to 11 out of the 37 giant stars that are common targets in the EXPRESS and PPPS. After excluding four compact binaries from the common sample, we obtained a fraction of giant planets (mp ≳ 1– 2 MJ) orbiting within 5 AU from their parent star of f = 33.3−7.1+9.0%. This fraction is slightly higher than but consistent at the 1σ level with previous results obtained by different radial velocity surveys. Finally, this value is substantially higher than the fraction predicted by planet formation models of gas giants around stars more massive than the Sun.
Key words: asteroseismology / techniques: radial velocities / planets and satellites: detection / planets and satellites: formation
RV and activity indicator Tables (A.1–A.8) are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (126.96.36.199) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/646/A131
Based on observations collected at La Silla - Paranal Observatory under programs ID’s 085.C-0557, 087.C.0476, 089.C-0524, 090.C- 0345, 096.A-9020(A), 098.A-9019(A) and through the Chilean Telescope Time under programs ID’s CN-12A-073, CN-12B-047, CN-13A-111, CN-2013B-51, CN-2014A-52, CN-15A-48, CN-15B-25 and CN-16A-13.
© ESO 2021
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