The disks of gas, dust and debris that surround young stars are breeding grounds for planets, a premise that every new exoplanet detection seems to confirm. But we know little about the disks themselves, and a key area of uncertainty continues to be the nature of disks around stars more massive than the Sun. What effect, for example, does their luminosity have on the disk, and how do the processes of large star formation affect planetary systems? The European Southern Observatory's Very Large Telescope is providing data that will shape a more refined view of these disks. At the heart of these new studies is HD 97048, a star some 600 light years away in the stellar spawning ground known as the Chameleon 1 dark cloud. HD 97048 is two and a half times as massive as the Sun, and fully forty times more luminous, making it ideal for such study. Image: Artist's impression of a flared proto-planetary disc, similar to what has been deduced from VISIR observations on ESO's Very Large Telescope...

The transit method has now bagged its 13th and 14th planets, both of them 'hot Jupiters' so close to their stars that their orbits are two and two and one-half days respectively. That makes for temperatures well over 1800 degrees Celsius, and adds more data points in our improbable collection of massive planets that all but skim their stars as they race around their orbits. One of the new planets, called WASP-1b, is in the constellation Andromeda, and is thought to be 1000 light years distant. WASP-2b, in Delphinius, is some 500 light years away. Behind the discovery is the UK consortium called SuperWASP -- Wide Angle Search for Planets. The astronomers involved are surveying millions of stars from robotic observatories in the Canary Islands and in South Africa. Each observatory uses eight wide-angle cameras, with a field of view 2000 times greater than a conventional astronomical telescope. The goal is to detect the faint dimming of starlight that flags a planetary transit, visible...

Brown dwarfs are clearly commonplace in the galaxy, but we know all too little about them. Thus the excitement about the recent imaging of a brown dwarf that orbits its star along with a planet. More information about that dwarf, HD 3651 B, has now surfaced thanks to a preprint passed along by Massimo Marengo (Harvard-Smithsonian Center for Astrophysics), a member of the team that discovered this interesting object. As we saw several days ago in these pages, an independent team led by Markus Mugrauer (University of Jena) has also submitted a later paper announcing the same object. Clearly, this faint brown dwarf has been the subject of much scrutiny, and deservedly so. For the primary, HD 3651, has already been subjected to radial velocity analysis, turning up a planetary companion of somewhat less mass than Saturn. Located in the constellation Pisces, HD 3651 is a bit less massive than our Sun, and the behavior of its known planet is unusual -- its orbit is highly elliptical, a...

As planet hunters catalog stellar wobbles and light-curves, some of them are working their way down through the various planetary types aiming at the ultimate discovery, an Earth-like world around another star. And if Lisa Kaltenegger has her way, they'll be able to tell us something about the existence of life on that planet. Kaltenegger faced a Washington DC audience yesterday to announce a new methodology for examining terrestrial worlds. Unable to be there myself, I attended via a much appreciated Webcast. Kaltenegger (Harvard-Smithsonian Center for Astrophysics) and Wesley Traub (JPL and CfA) are looking closely at the history of Earth's atmosphere to understand what happens in the various stages of planetary evolution. The development of life is one of many factors that changed the atmosphere in the past 4.5 billion years. When the day comes that we have spectroscopic data from exoplanets as small as Earth, we'll be able to study the signatures of the gases there to learn...

A Jupiter-sized planet with the density of cork? The idea seems farcical, but it's under discussion as I write at a news conference held by the Harvard-Smithsonian Center for Astrophysics (CfA). The planet, called HAT P-1, revolves around ADS 16402, a star much like our Sun that is part of a binary system some 450 light years away in the constellation Lacerta. The first planet found by the Hungarian Automated Telescope observing network, HAT P-1 may represent a new class of planet entirely. For despite a radius of 1.38 times Jupiter's, HAT P-1 has only half its mass. "This planet is about one-quarter the density of water," said Gaspar Bakos (CfA). "In other words, it's lighter than a giant ball of cork! Just like Saturn, it would float in a bathtub if you could find a tub big enough to hold it, but it would float almost three times higher." Intriguingly, the new world isn't the first planet with oddly low density. Another planet found by the transit method, HD 209458b, is also about...

Following hard on our discussion of HD 3651, a K-class dwarf whose brown dwarf companion was recently imaged, comes news that the Hubble Space Telescope has photographed something smaller still. CHRX 73 B orbits a low-mass red dwarf. Some would consider it a planet, others a brown dwarf; which camp you are in depends on what you use as a planetary marker. If it's mass, then this object, 12 times the mass of Jupiter, would probably be considered a planet. But team leader Kevin Luhman (Pennsylvania State) has other ideas. For if your marker is how the object formed, then a whole new set of criteria swim into view. Luhman argues that to be a planet, an object must have evolved from the gas and dust disk that circles a newly formed star. Whereas brown dwarfs are thought to form like any other star, from the collapse of huge clouds of hydrogen gas. They simply lack the mass to ignite hydrogen fusion in their cores. And Luhman seems to be on firm ground in making this distinction: "The...

Small telescopes doing amazing things. That's the theme of the day in exoplanet hunting, reinforced by the announcement of a new planet discovered by the Trans-Atlantic Exoplanet Survey (TrES). Small, automated equipment and off-the-shelf camera technology went into this work, which spotted the third transiting planet found with the kind of telescopes available to amateurs. "Hunting for planets with amateur equipment seemed crazy when we started the project," says David Charbonneau, an astronomer at the Harvard-Smithsonian Center for Astrophysics, "but with this discovery the approach has become mainstream." Image: A computer-generated simulation of TrES-2 crossing (transiting) the disk of its host star. TrES-2 transits farther from the disk center than any other known transiting planet. The transit of TrES-2 causes a drop in the brightness of its home star of about one and a half percent. This slight dimming of the star's light was noticed and measured by the TrES researchers, who...