Lauren Weiss and Jiayin Dong

From the calendar

Despite the importance of Jupiter and Saturn to Earth's formation and habitability, there has not yet been a comprehensive observational study of how giant exoplanets correlate with the architectural properties of close-in, sub-Neptune sized exoplanets. This is largely because transit surveys are particularly insensitive to planets at orbital separations > 1 AU, and so their census of Jupiter-like planets is incomplete, inhibiting our study of the relationship between Jupiter-like planets and the small planets that do transit. To investigate the relationship between close-in small, and distant giant planets, we conducted the Kepler Giant Planet Survey (KGPS). Using W. M. Keck Observatory HIRES, we spent a decade collecting 2858 RVs of 63 Sun-like stars that host 157 transiting planets. We had no prior knowledge of which systems would contain giant planets beyond 1 AU, making this survey unbiased with respect to previously detected Jovians. We announce RV-detected companions to 20 stars from our sample. These include 13 Jovians (0.3 MJ < M sin i < 13 MJ, 1 < a < 10 AU), 7 non-transiting sub-Saturns, and 3 stellar-mass companions. We present updated masses and densities of 84 transiting planets. The KGPS project leverages some of the longest-running, most data-rich RVs of the NASA Kepler systems yet, and will address whether giant planets help or hinder the growth of sub-Neptune sized and terrestrial planets. Future papers will examine the relationship between small, transiting planets and their long-period companions.

The close-in orbits of hot Jupiters (orbital periods of only a few days) have long puzzled astronomers. Although several formation mechanisms have been proposed, the dominant process remains uncertain. Here, I show that a population-level analysis of stellar obliquity, the angle between a host star’s spin axis and a planet’s orbital axis, can constrain the formation channels of hot Jupiters. Illuminatingly, the observed obliquity distribution of hot-Jupiter systems favors an origin involving high-eccentricity tidal migration driven by planet–planet interactions.