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Planet Formation

Content About: Planet Formation

Published: 12/13/2016 - 10:13am Type of Content: Article-Research Highlight

Astrophysicist Jeff Linsky and his colleagues recently created a sophisticated mathematical model of the outer atmosphere of the small M-dwarf star called GJ832. The new model fits well with spectral observations of the star made with the Hubble Space Telescope (HST). This accomplishment bodes well for two reasons: First, it provides a tool for better understanding M-dwarf stars––the most...

Published: 07/27/2016 - 1:41pm Type of Content: Article-Research Highlight

Fellow Phil Armitage and group collaborator Jacob Simon of the Southwest Research Institute are leading work to answer a central question about planet formation: How do pea- and pebble-sized objects orbiting within a protoplanetary disk evolve into asteroid-sized objects tens to hundreds of kilometers in size? This is an important question to answer because the eventual formation of planets...

Published: 10/16/2015 - 3:36pm Type of Content: Article-Research Highlight

Fellow Phil Armitage and his collaborator Jake Simon of the Southwest Research Institute recently conducted a theoretical study of turbulence in the outer reaches of an accretion disk around HD 163296, a nearby young star. Meanwhile, the Atacama large Millimeter/submillimeter Array (ALMA) in northern Chile observed the same accretion disk. There were intriguing and unexpected differences...

Published: 08/02/2013 - 7:39am Type of Content: Article-Research Highlight

What sets the stage for planet formation?

To search for answers to this question, research associate Jake Simon and his colleagues are performing a series of high-level computer simulations of the outer disks around young stars such as TW Hydrae, shown here. Simon’s daunting task is being facilitated with new information that has just started to come in from the Atacama Large Millimeter...

Published: 04/10/2013 - 12:17pm Type of Content: Article-Research Highlight

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.

Over millions of years, X-rays emitted by the central star evaporate the protoplanetary disk until it...

Published: 09/21/2011 - 6:00pm Type of Content: Article-Research Highlight

The Solar System has a remarkable number of planets. It includes four rocky planets (Mercury, Venus, Earth, and Mars), four giant gaseous planets, and countless smaller worlds. Early on, there may even have been a fifth rocky planet that collided with the Earth, forming the Moon. We owe the survival of so many terrestrial planets (and our own evolution as a species) to the...

Published: 01/20/2011 - 5:00pm Type of Content: Article-Research Highlight

Hot Jupiters — giant gas planets orbiting close to their parent stars — aren’t just scorched (at temperatures of >1000 K). They are also swollen up larger than can be explained by the intense heat from their host stars. Recently Fellow Rosalba Perna and her colleagues from Columbia University and the Kavli Institute for Theoretical Physics suggested a reason...

Published: 04/08/2010 - 6:00pm Type of Content: Article-Research Highlight

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...

Published: 02/09/2010 - 5:00pm Type of Content: Article-Research Highlight

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...

Published: 09/29/2009 - 6:00pm Type of Content: Article-Research Highlight

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...

Published: 07/08/2008 - 6:00pm Type of Content: Article-Research Highlight

Like people, planets can migrate far from where they were born. In the case of planets, they usually travel toward their parent star, but some may also move away. Some wind up in blistering proximity to their Sun-like parents, orbiting them in 1.2 to 8 days. Such orbits are well inside the magnetic-field-induced cavities that typically separate such stars from their planet-forming accretion...

Published: 04/08/2008 - 6:00pm Type of Content: Article-Research Highlight

Fellow Phil Armitage is excited about the discovery of several new galaxies in which a disk of water masers is orbiting within half a light year of the central massive black hole. Like their counterpart M106 (NGC 4258) discovered in 1995, these hot (600 K) water molecules mase, i.e., emit coherent radio wavelength photons when they return to lower energy states after being excited by...

Published: 02/09/2007 - 5:00pm Type of Content: Article-Research Highlight

If you wanted to see a new planet forming, the first thing you'd think of is looking in an accretion disk with a star forming in its center. The problem is it's virtually impossible to actually see a nascent planet inside a swirling, turbulent, and opaque disk of gas and dust. It's much easier to identify planets orbiting stars a billion years old (or older) whose accretion disks...

Published: 04/08/2006 - 6:00pm Type of Content: Article-Research Highlight

Black holes are pretty strange, sucking in not only nearby matter but also the space around it. These cosmic vacuum cleaners are powered by thin, gaseous accretion disks in orbit around them. Something drives the orbiting gas to spiral in toward the black hole, where all trace of it disappears forever into the singularity. One of the exciting challenges in astrophysics is to figure out the...

Published: 02/09/2006 - 5:00pm Type of Content: Article-Research Highlight

Scientists believe that planetary systems coalesce from disks of gas and dust orbiting a star. Similarly, stars can form within massive accretion disks orbiting a black hole. Determining the mechanisms that create stars and planets from these orbiting disks is a hot topic among astrophysicists, according to JILA Fellow Phil Armitage and colleagues W. K. M. Rice of the University of...

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Published: 03/05/2013 - 3:45pm Type of Content: Research Areas

Phil Armitage has been studying the formation and migration of planets around stars outside our solar system for more than a decade. He and his fellow planetary scientists know that during star formation, about 10% of the available mass doesn't end up in the star; this material becomes the building blocks of planets. In searches for planets circling more than a thousand nearby stars,...

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