![The fitted source and lens system positions as measured in the HST F606W (V −band; blue) and F814W (I−band; red) data. The contours show the 68%, 95%, and 99% confidence intervals for the V and I data, respectively. The measured V −band and I−band position of the (brighter) source star is nearly identical. We detect a weak (∼1.3σ) color-dependent centroid shift at the location of the lens system. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/10/First-Direct.png?resize=1200%2C720&ssl=1)
[astro-ph.EP] Nearly 25 years have passed since gravitational microlensing delivered its first exoplanet discoveries.
microlensing
Rogue Worlds 3
Free-floating, or “rogue”, planetary-mass objects have been discovered wandering through the Galaxy unbound to any star. The origins of these objects remain poorly understood, and likely involve a combination of […]
![Schematic overview of instability-inducing mechanisms through which planets may be ejected from a system. These mechanisms, each discussed throughout this work, include close approaches between neighboring planets (top left; Section 2), binary-induced instabilities (top center and right, and bottom left; Section 3), flyby encounters (bottom center; Section 4), and post-main-sequence orbital evolution (bottom right; Section 5).-- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/The-Dynamics.png?resize=1200%2C719&ssl=1)
Posted inExoplanets, -moons, -comets
The Dynamics Of Planetary Ejection
[astro-ph.EP] The ubiquity of free-floating planets inferred from microlensing and direct imaging surveys suggests that planetary ejection—a process in which planets initially born encircling a stellar host become gravitationally unbound—is […]
![Orbital trajectories of two example scattering experiments. Left: An interaction that results in a free-floating planet-moon pair. Right: An interaction that results in a free-floating planet and a separate free-floating moon. The starting points of the bodies are indicated by the black dots. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/07/Planet-moon.png?resize=1200%2C720&ssl=1)
Posted inStellar Cartography
Planet-moon Ejections In Close Stellar Encounters
[astro-ph.EP] Free-floating planet-moon pairs (FFPMs) may form when planetary systems experience close stellar encounters.
Posted inExoplanets, -moons, -comets
Free Floating Exoplanets or Merely Detached?
[Astrophysical Journal] Microlensing surveys suggest the presence of a surprisingly large population of free-floating planets, with a rate of about two Neptunes per star.
Posted inAstrochemistry, Astronomy & Telescopes, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Gas Giants, Ice Giant, Imaging & Spectroscopy, Press Release
NASA’s Roman Mission Preps to Unveil New Populations of Faraway Worlds
NASA’s Nancy Grace Roman Space Telescope is poised to make a major leap in the hunt for worlds outside our solar system, known as exoplanets. Scientists expect the mission to […]
Posted inAstrochemistry, Astrogeology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report
A Break In Planet Occurrence Near The Pebble Isolation Mass Should Be Observable By The Roman Microlensing Survey
Microlensing detections are uniquely well-suited to probing the population of planets outside the water iceline, down to planetary masses comparable to the Earth.
Posted inAstronomy & Telescopes, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Interstellar, Status Report
Laying the Foundation for a Comprehensive View of Transiting Exoplanets with the Galactic Bulge Survey
The primary science driver of the Roman Galactic Bulge Time-Domain Survey (GBTDS) is the detection and demographics of cold exoplanets via microlensing (Astro2010, Penny et al. 2019).
Posted inAstronomy & Telescopes, Brown Dwarfs, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Interstellar, Status Report
A Free-floating-Planet Microlensing Event Caused By A Saturn-mass Object
A population of free-floating planets is known from gravitational microlensing surveys. None have a directly measured mass, owing to a degeneracy with the distance, but the population statistics indicate that […]
Posted inAstronomy & Telescopes, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report, Stellar Cartography
Predictions Of The Nancy Grace Roman Space Telescope Galactic Exoplanet Survey. V. Detection Rates of Multiplanetary Systems In High Magnification Microlensing Events
The Nancy Grace Roman Space Telescope will expand the reach of gravitational microlensing surveys by increasing the number of events monitored and the precision of their light curves.