Four New Exoplanets and Hints of Additional Substellar Companions to Exoplanet Host Stars

Abstract

We present four new exoplanets: HIP 14810 b & c, HD 154345 b, and HD 187123 c. The two planets orbiting HIP 14810, from the N2K project, have masses of 3.9 and 0.76 M Jup . We have searched the radial velocity time series of 90 known exoplanet systems and found new residual trends due to additional, long period companions. Two stars known to host one exoplanet have sufficient curvature in the residuals to a one planet fit to constrain the minimum mass of the outer companion to be substellar: HD 68988 c with 8 M Jup < m sin i < 20 M Jup and HD 187123 c with 3 M Jup < m sin i < 7 M Jup , both with P > 8 y. We have also searched the velocity residuals of known exoplanet systems for prospective low-amplitude exoplanets and present some candidates. We discuss techniques for constraining the mass and period of exoplanets in such cases, and for quantifying the significance of weak RV signals. We also present two substellar companions with incomplete orbits and periods longer than 8 y: HD 24040 b and HD 154345 b with m sin i < 20M Jup and m sin i < 10 M Jup , respectively.

HD 5388 b is a 69 MJupcompanion instead of a planet

“…We did not detect an orbital signature because the obtained orbit has a very low significance of 71%, which confirms the result of Zucker & Mazeh (2001). -HD 195019 hosts a planet candidate with M 2 sin i = 3.70 M J (Wright et al 2007). We detected the astrometric orbit with a high significance of 98% and a very low inclination of 0.3 ± 0.1 • , which renders a stellar companion and confirms the result of Zucker & Mazeh (2001).…”

The Solar Twin Planet Search

“…In spite of these challenges, a number of Jupiter analog candidates have been discovered from long-duration planet surveys (see, e.g., Vogt et al 2000;Naef et al 2003;Wright et al 2007Wright et al , 2008Howard et al 2010;Boisse et al 2012;Marmier et al 2013;Wittenmyer et al 2014;Feng et al 2015). These surveys also demonstrate the prevalence of solar-like magnetic activity cycles, which can manifest in the stellar RVs Zechmeister et al 2013).…”

A Double Planetary System Around the Evolved Intermediate-Mass Star Hd 4732

“…Due to the increase in velocity precision and the duration of the planet search programs, not only single planets but also many multipleplanet systems have been discovered. Around solar-type stars, including those systems with long-term radial velocity trends, ∼30%-50% of stars with giant planets are multiple-planet systems (Fischer et al 2001;Wright et al 2007Wright et al , 2009, and systems comprising less massive planets such as super-Earths and Neptune-mass planets are more abundant (Mayor et al 2011;Howard et al 2012;Wittenmyer et al 2011b).…”