The Solar Neighborhood XLIX: Nine Giant Planets Orbiting Nearby K Dwarfs, and the CHIRON Spectrograph's Radial Velocity Performance

TL;DR

This study reports the discovery of nine exoplanet candidates around nearby K dwarfs using the CHIRON spectrograph, demonstrating its high precision and stability for radial velocity measurements in a large survey.

Contribution

The paper presents new exoplanet candidates, confirms a hot Jupiter, and evaluates CHIRON's performance for radial velocity surveys of K dwarfs up to 50 pc.

Findings

Nine exoplanet candidates identified around K dwarfs.

CHIRON achieves 5-20 m/s radial velocity precision.

Demonstrated instrument stability over various timescales.

Abstract

We report initial results of a large radial velocity survey of K dwarfs up to a distance of 50 pc from the Solar System, to look for stellar, brown dwarf, and jovian planets using radial velocities from the CHIRON spectrograph on the CTIO/SMARTS 1.5m telescope. We identify three new exoplanet candidates orbiting host stars in the K dwarf survey, and confirm a hot Jupiter from TESS orbiting TOI 129. Our techniques are confirmed via five additional known exoplanet orbiting K dwarfs, bringing the number of orbital solutions presented here to 9, each hosting an exoplanet candidate with a minimum mass of 0.5--3.0 $M_{jup}$. In addition, we provide a list of 186 nearby K dwarfs with no detected close companions that are ideal for more sensitive searches for lower mass planets. This set of stars is used to determine CHIRON's efficiency, stability, and performance for radial velocity work. For K dwarfs with V = 7--12, we reach radial velocity precisions of 5--20 ms$^{-1}$ under a wide range of observing conditions. We demonstrate the stability of CHIRON over hours, weeks, and years using radial velocity standards, and describe instrumental capabilities and operation modes available for potential users.