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Molding a Star System over 50 Million Years

Caption: Artist’s conception of the formation of a young gas giant, exoplanet Lk

Giant planets form inside a disk of gas and dust orbiting a new star. At first, gravitational interactions between the disk and the planets will keep planetary orbits circular, according to Fellow Phil Armitage. But, once the disk begins to disperse, things get very interesting.Read more »

Phil Armitage

Phil Armitage

Phil Armitage was born in 1971 just outside of London in Sevenoaks, Kent, England. He was keen on astronomy early in life. As an elementary school student, he kept abreast of extensive press coverage of the Voyager I spacecraft’s flight past Jupiter and Saturn during 1979 and 1980.  To encourage his passion for astronomy, Armitage’s parents bought him a six-inch reflecting telescope. Read more »

Planet Formation

Migrating planet Credit: Phil Armitage

Migrating planet Credit: Phil Armitage Phil Armitage studies the formation and migration of planets around stars outside our solar system. Read more »

Sculpting a Star System: The Outer Planets

Artist’s conception comparing the Epsilon Eridani star system to our own solar s

Fellow Phil Armitage and colleagues from the Université de Bordeaux and Google, Inc. are key players in the quest to understand the secrets of planet formation. Current theory posits that there are three zones of planet formation around a star (as shown in the figure). In Zone One, the hot innermost zone, small rocky planets form over a period of hundreds of millions of years. The planets form too slowly to accrete gas from the original planetary disk. Zone One is the terrestrial, or habitable, zone. Read more »

First Light

Simulation of gravitational radiation from the merger of two black holes. After

The merger of supermassive black holes is a hot topic in astrophysics. Such mergers may occur after the formation of black hole binaries during galaxy collisions. The mergers are predicted to emit gravitational waves, whose detection is the mission of the Laser Interferometer Space Antenna (LISA). In preparation for the LISA mission, which is scheduled for launch in 2018, Fellow Peter Bender is working with colleagues around the world to improve LISA’s design (see JILA Light & Matter, Summer 2006). Read more »

The Great Migration

Artist’s Conception of a Protoplanetary Disk Credit: NASA/JPL-Caltech

Fellow Phil Armitage studies the migration of gas giant planets through evolving protoplanetary disks. He and former JILA postdoc Richard Alexander (Universiteit Leiden) have designed relatively simple models that reproduce the observed frequency and distribution of extra-solar giant planets, many of which orbit very close to their stars. The models also replicate the masses, lifetimes, and evolution of protoplanetary disks. Read more »

Crafting Star Systems like Our Own

The HR 8799 planetary system. This is the first picture of a "solar system" beyo
Collage of Jupiter and its four planet-sized moons put together from photos take

Most known extrasolar planetary systems comprise planets whose orbits vary wildly from the nearly circular ellipses found in our solar system. This wide variation in eccentricity is thought to occur when large gas planets interact with each other, causing gyrations in planetary orbits, planet migrations toward and away from the central star, and even the ejections of planets out of the star system. These interactions are known as planet-planet scattering. While this mechanism is important, it can’t be the whole story because it doesn’t explain the architecture of the Solar System. Read more »