Microlensing events indicate that super-Earth exoplanets are common in Jupiter-like orbits

Area of Science:

• Exoplanetary science
• Gravitational microlensing
• Planet formation

Background:

• Super-Earth exoplanets are frequently found on short-period orbits.
• The abundance of super-Earths on wider orbits remains poorly understood.
• Gravitational microlensing is a key technique for detecting exoplanets on wide orbits.

Purpose of the Study:

• To constrain the abundance of super-Earths on wide orbits.
• To investigate the distribution of planet-to-star mass ratios for wide-orbit planets.
• To explore potential differences in exoplanet formation processes.

Main Methods:

• Observation of the gravitational microlensing event OGLE-2016-BLG-0007.
• Analysis of a larger sample of exoplanets from a microlensing survey.
• Statistical inference of planet mass ratio distributions.

Main Results:

• Detection of a super-Earth with a significant planet-to-star mass ratio on a wide orbit (longer than Saturn's).
• Inferred abundance of approximately 0.35 super-Earths per star on Jupiter-like orbits.
• Evidence for a bimodal distribution of exoplanet mass ratios, with separate populations for super-Earths and gas giants.

Conclusions:

• Super-Earths are common on wide, Jupiter-like orbits.
• The observed distribution suggests distinct formation mechanisms for super-Earths and gas giants.
• Gravitational microlensing provides crucial insights into exoplanet populations on wide orbits.