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

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 1.5 m 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.

The LHS 1678 System: Two Earth-sized Transiting Planets and an Astrometric Companion Orbiting an M Dwarf Near the Convective Boundary at 20 pc

“…To check for false positives in the form of a spectroscopic binary or background EB not resolved by the previously described follow-up, we acquired eight RV measurements using the CHIRON echelle spectrograph (Schwab et al 2010;Tokovinin et al 2013;Paredes et al 2021) on the CTIO/ SMARTS 1.5 m in Chile (program ID 19A-0339; see Table 5). Our measurements, spanning 410-870 nm, were taken from 2019 August 27 to September 6 using slicer mode with R ∼ 80,000.…”

TESS Giants Transiting Giants II: The hottest Jupiters orbiting evolved stars

“…Data were obtained in slicer mode, which uses a fiber feed and an image slicer to yield R ≈ 79,000 over the spectral range 410 nm to 880 nm. The spectra were extracted as per Paredes et al (2021). Radial velocities were measured from the spec-tra via a cross correlation between each epoch against a median-combined observed template.…”

Spectroscopic orbits of subsystems in multiple stars. VIII

“…Fifteen hours of observing time were allocated to this program per semester. Observations were made with the fiber-fed CHIRON optical echelle spectrograph (Tokovinin et al 2013;Paredes et al 2021) by the telescope operators in service mode. The spectra taken with the image slicer have a resolution of 85,000.…”