Jupiter-like planets might be common in a low-density environment

Abstract

Radial velocity surveys suggest that the Solar System may be unusual and that Jupiter-like planets have a frequency < 20% around solar-type stars. However, they may be much more common in one of the closest associations in the solar neighbourhood. Young moving stellar groups are the best targets for direct imaging of exoplanets and four massive Jupiter-like planets have been already discovered in the nearby young β Pic Moving Group (BPMG) via high-contrast imaging, and four others were suggested via high precision astrometry by the European Space Agency's Gaia satellite. Here we analyze 30 stars in BPMG and show that 20 of them might potentially host a Jupiter-like planet as their orbits would be stable. Considering incompleteness in observations, our results suggest that Jupiter-like planets may be more common than previously found. The next Gaia data release will likely confirm our prediction.

Fig. 1. Mass ratio q = M_B/M_A as a function of the semi-major axis a (in au) for companions (both stellar and substellar) to stars in the BPMG.

Filled circles are objects detected in imaging; open squares are companions detected using other techniques. Companions circled are those that make unstable the orbits of Jupiter-like planets. The solid, long-dashed and short-dashed red lines represent the detection limits in typical high-contrast imaging observations for the stars farthest, median, and closest to the Sun, respectively. The solid black line marks the detection limit of Gaia as separate entries; the dash-dotted black line is the predicted astrometric detection limit of Gaia DR4 release (expected not before the end of 2025) for G-dwarfs at 50 pc^, , comparable to the median distance of the BPMG members. The light blue area is the one corresponding to the Jupiter-like planets. Source data are provided as a Source Data file.

Fig. 2. Run of the mass of the target stars (in M_⊙) as a function of distance d in parsec.

Different symbols are used for those stars around which a Jupiter-like planet has been detected using HCI (black filled squares), there is an indication of a similar companion from PMa (red triangles), there is a binary companion that makes unstable the orbits of potential Jupiter-like planets (crosses), there is no detection (open circles) and those lacking PMa data (open triangles). Source data are provided as a Source Data file).

Fig. 3. Diagrams showing the mass of companions (in M_⊙) that may be responsible for the observed Proper Motion anomaly (PMA) as a function of semi-major axis a in au (blue solid line).

They are compared with 90% confidence upper limits obtained from the Gaia RUWE parameter (green dashed line), the upper limit from high-contrast imaging (HCI) with SPHERE (orange solid line), and the upper limit from RVs (red dotted line). The solid violet lines mark the position of known debris disks and the dash-dotted violet lines are the outer edge of the stability region due to the presence of these disks or of known companion (HIP 10679). Upper left panel: HIP 560, HCI from Dahlqvist et al.; Upper right panel: HIP 10679, HCI from Dahlqvist et al.; Lower left panel: HIP 84586 HCI from Asensio-Torres et al.; Lower right panel: HIP 88399, HCI from Mesa et al.. The orange area is occupied by Jupiter-like planets. The companions responsible for the PMa should be close to the solid blue line, below the dashed green, the solid orange line, the dotted red line, and the left of the dash-dotted violet line.