Our second transiting Neptune-mass planet has been discovered via the HAT Network of small, automated telescopes maintained by the Harvard-Smithsonian Center for Astrophysics. HAT-P-11b is described by Greg Laughlin at systemic (thanks to many who sent this link): HAT-P-11b is quite similar in mass and radius to Gliese 436b, and it's actually somewhat larger than Neptune on both counts. When the mass and radius are compared to theoretical models, it's clear that, like Gliese 436, it's mostly made of heavy elements (that is, some combination of metal, rock and "ice") with an envelope of roughly 3 Earth masses of hydrogen and helium). It's completely dwarfed when placed next to an inflated hot Jupiter, HAT-P-9b, for instance... The advantages of a detected transit are great. Couple the transit light curve with radial velocity measurements and you can work out the mass and radius of the transiting planet. Moreover, the opportunity to investigate planetary atmospheres comes into play...

If, as we have often speculated in these pages, there is a brown dwarf closer to us than the Centauri stars, it may well be the WISE mission that finds it. The Wide-field Infrared Survey Explorer is a 40 cm telescope cooled below 17 K (-430 Fahrenheit) that will image the entire sky in four infrared wavelengths. If we're looking for nearby brown dwarfs, an all-sky survey like this is the way to go, because such stars should be distributed uniformly in the space around us. According to information Amanda Mainzer (JPL) presented yesterday at the American Astronomical Society meeting in Long Beach (CA), brown dwarfs are now thought to make up two-thirds of the stars in our stellar neighborhood, most of them as yet undetected. One of them might well be closer than the 4.3 light years that separate us from Alpha Centauri. And WISE should be up to the challenge of finding it, being able to detect cool brown dwarfs (down to 200 K) at Centauri distance and objects down to Jupiter-mass if...

The American Astronomical Society meeting now in session in Long Beach (CA) is already making news. Led by Michael Jura (UCLA), a team of scientists has used Spitzer Space Telescope data to study six white dwarf stars that are surrounded with the remains of asteroids. The assumption here is that these materials are a likely indication of planetary formation in these systems, for they're the same materials that go into making up the Earth and other rocky worlds in our own Solar System. "If you ground up our asteroids and rocky planets, you would get the same type of dust we are seeing in these star systems," says Jura, who presented the results at the meeting this morning. "This tells us that the stars have asteroids like ours -- and therefore could also have rocky planets." When a star like our Sun reaches the end of its life and becomes a red giant, it consumes any inner planets and perturbs the orbits of the surviving planets and asteroids. A white dwarf is the end result of this...

The title of yesterday's post -- 'The Odds on Centauri' -- would fit well with today's musings. Alpha Centauri makes us ponder the odds not just in terms of interstellar bets and future space probes, but also in terms of the likelihood of life around these stars. And after all, 2008 saw significant work on this question, including the contributions of Philippe Thébault (Stockholm Observatory) and colleagues, whose studies of Centauri A and B show that while stable planetary orbits exist there, the odds on those planets forming in the first place are long. Greg Laughlin (UC-Santa Cruz) isn't necessarily daunted by this work (he explains why here), but the planet-hunter extraordinaire is realistic about life-bearing planets in this environment, and even more judicious about the possibility of a technological society making its home in the system. The question rises naturally out of recent publicity given the 20th Century Fox film The Day the Earth Stood Still, in which it was...

A new camera called OPTIC (Orthogonal Parallel Transfer Imaging Camera), built at the University of Hawaii, has clarified our view of the distant world known as WASP-10b. Transits are helpful because they allow us to measure the size of the observed planets, and in this case, WASP-10b turns out to be not one of the most bloated exoplanets yet found, as once thought, but one of the densest. Orbiting some 300 light years from Earth, the planet's diameter is now known to be only six percent larger than Jupiter's, although it is three times more massive, with a corresponding density three times that of Jupiter. OPTIC is mounted on the University of Hawaii's 2.2-meter telescope on Mauna Kea. If you compare what it can do with its highly sensitive and stable detector to the best results from charge-coupled devices (CCDs), you find a photometric precision two to three times higher. According to this news release from the university's Institute for Astronomy, that's comparable to the most...

The Kepler mission launches March 5, a date to circle on your calendar. Kepler may become the first instrument to detect an Earth-size planet in the habitable zone of another star, using the transit method to examine 100,000 stars in its 3.5 year mission. The 0.95-meter diameter telescope is now at Ball Aerospace & Technologies (Boulder, CO), having passed the necessary environmental tests that demonstrate its space-worthiness. And word has just come that it has also passed the necessary 'pre-ship review' for transit to Florida in January. Image: An artist's rendering of what our galaxy might look like as viewed from outside. Our sun is about 25,000 light years from galactic center. The cone illustrates the neighborhood of our galaxy that the Kepler Mission will search to find habitable planets. Credit: Jon Lomberg. The image above, the work of the fine space artist Jon Lomberg, gives an idea of where Kepler will be looking. As always, Lomberg (creator of the gorgeous Galaxy Garden...