[astro-ph.EP] Compact multi-planet systems orbiting ultracool dwarfs, such as TRAPPIST-1, may be a major population of terrestrial worlds with poorly constrained demographics.
microlensing
![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)
Posted inExoplanets, -moons, -comets
First Direct Identification Of A Multi-Star Microlens System Hosting A Planet
[astro-ph.EP] Nearly 25 years have passed since gravitational microlensing delivered its first exoplanet discoveries.
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 […]