• DOI:10.1051/0004-6361/201525853
• Corpus ID: 52971677

Giant planets around two intermediate-mass evolved stars and confirmation of the planetary nature of HIP 67851c

@article{Jones2015GiantPA,
  title={Giant planets around two intermediate-mass evolved stars and confirmation of the planetary nature of HIP 67851c},
  author={M. I. Jones and James S. Jenkins and Patricio Rojo and Claudio H. F. Melo},
  journal={Astronomy and Astrophysics},
  year={2015},
  volume={580}
}

• M. I. Jones, J. Jenkins, +1 author C. Melo
• Published 25 May 2015
• Physics
• Astronomy and Astrophysics

Context. Precision radial velocities are required to discover and ch aracterize planets orbiting nearby stars. Optical and near infrared spectra that exhibit many hundreds of absorption lines can allow the m s −1 precision levels required for such work. However, this means that studies have generally focused on solar-type dwarf stars. After the main-sequence, intermediate-mass star s (former AF stars) expand and rotate slower than their progenitors, th us thousands of narrow absorption lines appear in the optical region, permitting the search for planetary Doppler signals in the data for these types of stars. Aims. In 2009, we began the EXPRESS program, aimed at detecting substellar objects around evolved stars, and to study the effects of the mass and evolution of the host star on their orbital and physical properties. Methods. We have obtained precision radial velocity measurements for the giant stars HIP 65891 and HIP 107773, from CHIRON and FEROS spectra. Also, we obtained new radial velocity epochs for the star HIP 67851, which is known to host a planetary system. Results. We present the discovery of two giant planets around the intermediate-mass evolved star HIP 65891 and HIP 107773. The best Keplerian fit to the HIP 65891 and HIP 107773 radial veloc ities leads to the following orbital parameters: P=1084.5 d; mb sini= 6.0 MJ ; e=0.13 and P=144.3 d; mb sini= 2.0 MJ ; e=0.09, respectively. In addition, we confirm the planetary na ture of the outer object orbiting the giant star HIP 67851. The orbital parameters of HIP 67851 c are: P=2131.8 d, mc sini = 6.0 MJ and e=0.17. Conclusions. With masses of 2.5 M⊙ and 2.4 M⊙ , HIP 65891 and HIP 107773 are two of the most massive stars known to host planets. Additionally, HIP 67851 is one of five giant stars th at are known to host a planetary system having a close-in planet (a< 0.7 AU). Based on the evolutionary states of those five stars, we conclude that close-in planets do exist in multiple systems around subgiants and slightly evolved giants stars, but probably t hey are subsequently destroyed by the stellar envelope during the ascent of the red giant branch phase. As a consequence, planetary systems with close-in objects are not found around horizontal branch stars.