Finding solar system analogs is tricky business, as we saw yesterday when examining the discovery of Jupiter and Saturn-class worlds around a distant star. That find, I notice, is getting some attention in the popular media as an indication that our Solar System may not be unique. But take a look at the gas giant recently found around HD 154345 if you want to see an even closer analog to our own system. HD 154345b is a single world, to be sure, but it orbits a G8 dwarf much more like the Sun than the diminutive star examined yesterday, and it's a close match for Jupiter not only in size but orbital position. The planet's minimum mass is 0.95 Jupiter's, and its 9.2 year circular orbit carries it around its star at a distance of some 4.2 AU. Sound familiar? What's happening around HD 154345 is more or less what a distant astronomer using our current technologies would see if observing our Solar System. Rather than using microlensing, the discovery team here put radial velocity...

We always have to watch our preconceptions, an early one in the exoplanet game being that solar systems around other stars would look pretty much like our own. Then we started the whole exoplanet discovery binge by finding planets around a pulsar, of all things, and went on to the terrifically odd world of 'hot Jupiters,' whose existence had not been predicted by most theorists. Now we've gotten used to the idea that solar systems come in huge variety, but finding one that looks more or less like ours would still be comforting, and would make it seem more likely that there are other 'Earths' out there, perhaps teeming with life. Today and tomorrow we look at two such finds, noting the resemblance to what we have around Sol and pondering the implications for the broader planet search. First up is not a single but a double planetary find, two worlds that inhabit a place much like that of Jupiter and Saturn in our Solar System. Not only is this an intriguing discovery in itself, but...

We have a long way to go in the study of circumstellar disks, especially around smaller stars. Given the difficulty of making such observations, work at the Subaru Telescope has focused on stars more massive than the Sun in hopes of studying the more apparent structure of the disks around such stars. But FN Tauri is an exception. The young star is a tenth of the Sun's mass, its disk seven times lighter than the lowest mass disk previously imaged, which was around the star TW Hydrae. The hope is to extend our knowledge of planetary formation more broadly across stellar types to learn what kind of worlds they form and where. The team of Japanese researchers performing this work used the Coronagraphic Imager with Adaptive Optics (CIAO) at the Subaru Telescope. What they've learned about FN Tauri is that the thick, roughly circular disk, with a radius of 260 AU, is relatively featureless at this point in the star's evolution (FN Tauri is thought to be a mere 100,000 years old). Thus far...

When you have assets in space, the thing to do is redeploy them as needed. That creates what's called an 'extended mission,' and the latest spacecraft to get one is Deep Impact, the vehicle whose impactor made such a splash when it was driven into comet Tempel 1 in the summer of 2005. That July 4 explosion was memorable enough, but under the name EPOXI the doughty craft leaves its vaporized impactor behind and moves on to two other missions, one of which has direct extrasolar applications. For one of EPOXI's twin goals is to observe five nearby stars known to have transiting exoplanets. Observations began on January 22. The 'hot Jupiters' around the five stars have been confirmed previously, but EPOXI's mission is to see whether any of these transiting gas giants is accompanied by other worlds in the same stellar system. Perhaps the most intriguing aspect of the investigation is summed up by Drake Deming (NASA GSFC): "We're on the hunt for planets down to the size of Earth, orbiting...

Watching two suns over Tatooine's sky in the original Star Wars movie was a breathtaking experience, particularly given where most science fiction films were at the time. Here was an attempt to convey a truly alien landscape. But a second thought quickly came unbidden. Was this planet not in an extremely unstable orbit, moving around both stars simultaneously in an obvious habitable zone? The suspicion was that a planet could orbit one or the other members of a binary system, but surely not both unless its orbit were extended so far out into the planetary nether regions as to make life doubtful. Image: The twin suns of Tatooine. Are planetary orbits like this possible? Credit: © Lucasfilm Ltd. & TM. All Rights Reserved. That was back in the 1970s, of course, but take a look at the situation today. The 'hot Jupiter' in the triple system HD 188753 is interesting, but the planet in question orbits but one of the stars. The early discussion of HD 188753 Ab was quick to raise the Tatooine...

We're still arguing about how giant planets form around Sun-like stars, but terrestrial planets seem to be less controversial. Assuming the model is right, we start with a swarm of planetesimals in the range of one kilometer in size. As these objects grow, out to a range of at least 2 AU, the largest bodies at some point go through a runaway period of chaotic growth marked by collisions. Emerging from the debris should be terrestrial worlds, some in Earth-like orbits. Add to this the fact that gas and dust disks seem to be relatively routine outcomes of star formation and you have an indication that small rocky planets may be widespread. The problem with all this is that theory has to be matched with observation. On that score, new work by Mike Meyer (University of Arizona) and colleagues Lynne Hillenbrand and John Carpenter (California Institute of Technology) is instructive. The researchers chose to look at mid-range infrared emissions at the 24 micron level, a range chosen because...