Abstract
Abstract We used high-precision radial velocity measurements of FGKM stars to determine the occurrence of giant planets as a function of orbital separation spanning 0.03–30 au. Giant planets are more prevalent at orbital distances of 1–10 au compared to orbits interior or exterior of this range. The increase in planet occurrence at ∼1 au by a factor of ∼4 is highly statistically significant. A fall-off in giant planet occurrence at larger orbital distances is favored over models with flat or increasing occurrence. We measure 14.1 − 1.8 + 2.0 giant planets per 100 stars with semimajor axes of 2–8 au and 8.9 − 2.4 + 3.0 giant planets per 100 stars in the range 8–32 au, a decrease in occurrence with increasing orbital separation that is significant at the ∼2σ level. We find that the occurrence rate of sub-Jovian planets (0.1–1 Jupiter masses) is also enhanced for 1–10 au orbits. This suggests that lower-mass planets may share the formation or migration mechanisms that drive the increased prevalence near the water–ice line for their Jovian counterparts. Our measurements of cold gas giant occurrence are consistent with the latest results from direct imaging surveys and gravitational lensing surveys despite different stellar samples. We corroborate previous findings that giant planet occurrence increases with stellar mass and metallicity.
Highlights
Expanding and characterizing the population of known exoplanets with measured masses and orbital periods is crucial to painting a more complete picture of planet formation and evolution
Using our broken power-law model, we find a median power-law slope inside the break of 0.72-+00..2106, which is 2σ higher than the power-law slope measured by Cumming et al (2008) (0.26 ± 0.1). This difference is likely caused by the single power-law model being pulled to lower values due to neglecting a flattening or turnover in occurrence at long orbital periods since Cumming et al (2008) was limited to planets orbiting inside 3 au
We utilize the catalog of stars, radial velocity (RV)-detected planets, and completeness contours from Rosenthal et al (2021) to measure giant planet occurrence as a function of semimajor axis
Summary
Expanding and characterizing the population of known exoplanets with measured masses and orbital periods is crucial to painting a more complete picture of planet formation and evolution. Groundbased radial velocity (RV) surveys measure the Doppler shifts of stellar spectra to discover exoplanets and characterize their orbits and masses. These surveys have provided landmark discoveries that shaped our understanding of the formation and architectures of other worlds (e.g., Mayor & Queloz 1995; Marcy et al 2002; Tamuz et al 2008). The Keck Planet Survey (Cumming et al 2008) used 8 years of RVs from Keck–HIRES (Vogt et al 1994) to make the first broad measurement of giant planet occurrence (M sin i 0.1MJ) This survey discovered an increase in the abundance of giant planets for orbits near the water–ice line and found that about 10% of Sunlike stars have giant planets with a semimajor axes of
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