The microlensing method is particularly good at finding small, distant planets around small stars.
The microlensing method is particularly good at finding small, distant planets around small stars.
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Left: Most known exoplanets have been discovered by the radial velocity (RV) and transit methods (triangles and squares, respectively). Those discoveries are biased toward finding planets around stars similar in mass to our sun (more yellow) and closer to their stars than the Earth (semi-major axis < 1). These techniques are particularly bad at finding planets beyond the orbit of the Earth and smaller than 30 times the Earth (in the lower right quadrant of the diagram). Right: Microlensing planet discoveries (circles) uniquely occupy this region of planet parameter space and probe planet around smaller stars (black/purple) offering novel insights into the range of semi-major axes where gas giant planets like Jupiter are expected to form.
Data Credit: NASA Exoplanet Archive accessed 28 February 2025.
Korea Microlensing Telescope Network (KMTNet)
Korea Microlensing Telescope Network (KMTNet)
I am the SAO Deputy Science-PI of KMTNet, which uses telescopes at three different sites (CTIO/Chile, SAAO/South Africa, SSO/Australia) with identical wide-field cameras to continuously monitor millions of stars in the Galactic Bulge to find and monitor microlensing events in real-time.
Credit: Westlake University
Microlensing events indicate that super-Earth exoplanets are common in Jupiter-like orbits
Microlensing events indicate that super-Earth exoplanets are common in Jupiter-like orbits
April 24, 2025 -- KMTNet published an article in Science magazine with three major results:
1. The discovery of a small planet in an orbit similar to Saturn’s. This is the smallest mass-ratio exoplanet detected by microlensing to date.
2. This planet is part of a larger sample that shows that super-Earth planets between the orbits of Earth and Saturn are abundant. The sample includes planets with mass-ratios a factor of 8 smaller than in previously analyzed samples and 3 times as large.
3. The overall distribution of planet mass ratios shows evidence of structure that could reflect planet formation processes, where the “mass ratio” is the mass of the planet relative to the mass of the host star. Specifically, the distribution suggests that the planets can be separated into two populations, one of super-Earths and Neptunes and one of more
Press release: https://www.cfa.harvard.edu/news/astronomers-find-far-flung-super-earths-are-not-farfetched
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