A Six-Planet System Around the Star HD 34445

TL;DR

This paper reports the discovery of a six-planet system around star HD 34445 using 18 years of radial velocity data, revealing a highly multi-planet configuration with long orbital periods and low amplitude signals.

Contribution

It provides the first detailed characterization of a six-planet system with long-period planets using extensive radial velocity observations.

Findings

Six planets with periods of 49 to 6770 days identified.

Planets have minimum masses ranging from 0.05 to 0.63 Jupiter masses.

The system's architecture is unlike our solar system or typical Kepler systems.

Abstract

We present a new precision radial velocity dataset that reveals a multi-planet system orbiting the G0V star HD 34445. Our 18-year span consists of 333 precision radial velocity observations, 56 of which were previously published, and 277 which are new data from Keck Observatory, Magellan at Las Campanas Observatory, and the Automated Planet Finder at Lick Observatory. These data indicate the presence of six planet candidates in Keplerian motion about the host star with periods of 1057, 215, 118, 49, 677, and 5700 days, and minimum masses of 0.63, 0.17, 0.1, 0.05, 0.12 and 0.38 Jupiter masses respectively. The HD 34445 planetary system, with its high degree of multiplicity, its long orbital periods, and its induced stellar radial velocity half-amplitudes in the range $2 \,{\rm m\, s^{-1}} \lesssim K \lesssim 5\,{\rm m\, s^{-1}}$ is fundamentally unlike either our own solar system (in which only Jupiter and Saturn induce significant reflex velocities for the Sun), or the Kepler multiple-transiting systems (which tend to have much more compact orbital configurations)