In a world dominated by short-term thinking, we tend to be driven by media cycles. That makes the coverage of science, among other subjects, problematic. Science operates through the analysis of detail as various minds subject a problem to hypotheses that can be tested experimentally. In other words, good science often takes time, which is why situations like the Gliese 581c story can be so frustrating. Announce a habitable planet around another star and the media love you. Spend months and (if needed) years subjecting the habitability question to analysis and you're not on the public radar. Many scientists have come to question whether Gliese 581c is remotely habitable; some even argue for habitability for the next planet out, Gliese 581d. We're still trying to weigh the data, and such deliberate processes aren't the sort of thing to replace the latest Hollywood starlet scandals on CNN. The good scientist ignores media vagaries and proceeds with the painstaking details. The hunt for...

HD 98800 is an unusual system indeed. About 150 light years away in the constellation TW Hydrae, the four stars that make it up consist of two binary pairs that circle each other. The distance between the two pairs is about 50 AU, which is roughly the average distance between Pluto and the Sun. Imagine having, instead of icy Kuiper Belt objects, a binary star system at the edge of our Solar System. Note: The reference above should probably be to the TW Hydrae association, not 'constellation,' as noted in the comments below. Image: This artist concept depicts the quadruple-star system HD 98800. The system is approximately 10 million years old, and is located 150 light-years away in the constellation TW Hydrae. HD 98800 contains four stars, which are paired off into doublets, or binaries. The stars in the binary pairs orbit around each other, and the two pairs also circle each other like choreographed ballerinas. Credit: NASA/JPL-Caltech/T. Pyle (SSC-Caltech). The idea of planet...

What are the two most fundamental properties of the stars we study? If you said mass and chemical composition, you get the prize, at least as determined by the California & Carnegie Planet Search team. Their new paper lays out the discovery of a gas giant orbiting the M-class red dwarf GJ 317. And they first discuss the discovery in the context of the core accretion model for planetary formation, and the correlation between the metallicity of a star and the chances of its harboring detectable planets. The notion seems sound: The host star inherits its characteristics from the same disk out of which the planets around it form. If you increase the amount of metals in the system (metals being defined as elements higher than hydrogen and helium), you increase the surface density of solid particulates, and that ought to bump up the growth rate for the core materials that become planets. In a gas giant, such a core then becomes massive enough to capture a gas envelope. But the case around...

Astronomers have found a highly elliptical debris disk around the star HD 15115, one that seen virtually edge-on from Earth gives the appearance of a needle running straight through its star. The disk was first imaged by the Hubble Space Telescope in 2006, its unusual shape causing astronomers to request near-infrared imaging by the W.M. Keck Observatory in Hawaii. Keck's images, in conjunction with the Hubble data, revealed the disk's uncommon blue color. So what's going on around this F-class star? First of all, let's distinguish between protoplanetary disks, which give birth to planets, and debris disks like this one, which resemble our own Kuiper Belt. The latter are made up of the remnants of planetary formation. This debris disk seems to extend some ten times further from its star than the Kuiper Belt, according to a Keck news release, though our limited knowledge of the Kuiper Belt makes me a bit wary of the statement, as the latter's dimensions are still under active...

Centauri Dreams sometimes gets e-mail from readers asking how research results can be so contradictory. We've discussed gas giants around red dwarf stars, for example, noting theories that such planets are rare in this environment. And then we come up with stars like Gliese 876 and GJ 317, both red dwarfs, and both sporting not one but two gas giants as companions. But stand by, for in a moment we'll look at new evidence that outer gas giants are indeed rare, and not just around M dwarfs. What's going on? The answer is that exoplanetary studies are a work in progress, and will continue to be as far into the future as I can see. We have identified over 200 exoplanets in a galaxy of several hundred billion stars. You bet we're going to find anomalous situations that challenge every theory we have. And the idea is to put hard scientific work out there for review and critique, noting methodologies and explaining conclusions, thus letting other scientists have a go at the same data. Those...

Probing planetary atmospheres is tricky business at the best of times, but when you're limited to planets you can't even see, the project seems well nigh insurmountable. Nonetheless, astronomers using the Spitzer space telescope are having some success working in the infrared. They focus on transiting hot Jupiters, and earlier this year were able to obtain spectra of exoplanetary light from two such worlds, HD 189733b and HD 209458b. We discussed that work earlier and noted that no water vapor was found in the atmosphere of either planet, despite earlier predictions that it would be. Now a team led by Giovanna Tinetti (Institute d'Astrophysique de Paris) has made further observations of HD 189733b, studying changes in the infrared light from the star as the planet transits, and thus filters the light through its own planetary atmosphere. Working at three different wavelengths, the study showed the clear signature of water. Image: This plot of data from NASA's Spitzer Space Telescope...

Since we've just been looking at stellar metallicity and planet formation, news from the European Southern Observatory catches my attention. A new paper from ESO astronomers discusses the question of planetary debris falling onto the surface of stars, and its effects on what we observe. Evidence has been accumulating that planets tend to be found around stars that are enriched in iron. On average, stars with planets are almost twice as rich in metals as stars with no known planetary system. But what exactly does this result mean? On the one hand, it's possible that stars that are rich in metals naturally enhance planet formation. But the reverse is also possible: It could be that debris from the planetary system could have polluted the star itself, so that the metals we see aren't intrinsic to the star. Bear in mind that a stellar spectrum shows only the star's outer layers, so we can't be sure what's at the core. And in-falling planetary debris would stay in the star's outer...