The much anticipated Nantes conference on Extrasolar Super-Earths is already paying off big in the form of a triple system of such planets. Found around the star HD 40307, the planets are among the 45 candidate worlds recently identified by European scientists using the HARPS instrument, a spectrograph mounted on the European Southern Observatory's 3.6-meter telescope at La Silla. The survey focused on F, G and K-class stars, finding 45 potential planets, all of which are below 30 Earth masses and show an orbital period shorter than fifty days. What's happening here testifies to the growing sophistication of our tools. While most of the 300+ positively identified exoplanets have been found around Sun-like stars, they have so far tended to be gas giants. Teasing smaller planets out of the data requires long observing runs -- HD 40307, for example, has been under active study for five years -- and it also requires the greater precision of instruments like HARPS. "With the advent of...

The latest Carnival of Space is up at Out of the Cradle, where this week's interstellar focus is delivered by Steinn Sigurdsson (Penn State), who takes a look at the new planet with the tongue-twisting name: MOA-2007-BLG-192Lb. We focused in on this one just a few days ago, intrigued by its small size (about three Earth masses) and its orbit around a low-mass star that is either a brown dwarf or a low mass M-dwarf. But note the play in the numbers from this microlensing detection, which suggests the mass could actually be as low as 1.7 Earth masses or as high as 8.2. The discovery paper is stuffed with the relevant analysis of the statistics and how the team's conclusions were arrived at. Let me quote Steinn on the possible significance of this find, which should have some resonance here: It is very hard to draw a robust conclusion from a single data point, the formal uncertainties are infinite; but, this is a small corner of the observing parameters space, low mass stars have low...

Yesterday's story on the smallest exoplanet yet discovered somewhat obscured work on brown dwarfs released at the same conference. But this year's meeting of the American Astronomical Society has been filled with interesting items, and I don't want to neglect the latest news about a type of star that may be as plentiful as any in the cosmos. We don't know that that is the case, but we have much to learn about brown dwarfs as we compile a census of those in the Sun's neighborhood, including the question of what kind of planets might circle them. New observations studied by Michael Liu (University of Hawaii) and team have now been able to determine the masses of a number of brown dwarfs, with findings that suggest the shape of future research. Says Liu: "Mass is the fundamental parameter that governs the life-history of a free-floating object, and thus after many years of patient measurements, we are delighted to report the first masses of the very faintest, coldest brown dwarfs. After...

Smaller and smaller planets keep coming into view. A prime goal, of course, is to find something around the size of the Earth, implying as it would the existence of a world that might be like ours in other ways. My suspicion is that one day soon a transit study is going to come up with an exoplanet that's closer to the size of Mars (definitely possible with today's technologies), and we'll skip right past the 'Earth twin' point before finding a planet that really is close to the same diameter. But so far we're still looking at worlds larger than Earth, like the tongue-twisting MOA-2007-BLG-192Lb, now thought to be the lowest mass planet ever found around another star. Announced today at the American Astronomical Society's meeting in St. Louis, the new planet orbits a brown dwarf. At six percent of the mass of the Sun (and thus unable to sustain nuclear reactions in its core), the host is the lowest mass star to have a companion with a planetary mass ratio. But the fudge factor in the...

My local paper is running a story on page 11A entitled "Astronomers Report Earth-like Planet." It's a tantalizing headline, but obviously one that bears further investigation. For what's being reported here is background information on one of the 45 planets -- I should say 'candidate' planets -- recently discussed at the Boston meeting of the IAU. These have been extracted from the HARPS planet survey, but we'll probably have to wait until mid-June for further confirmation, which may well occur at the upcoming Extrasolar Super-Earths workshop in Nantes. This would be an interesting world if things do play out, a rocky 'super Earth' just over four times as massive as Earth, and hence the smallest world yet in our attempt to find planets not so different from our own. If the press continues to generate a buzz about this, we should look at the contrast with the Gliese 581 story. There we wound up with two planets of astrobiological interest, one apparently on the inner edge of the...

I recently wrote about EPOXI, the dual-purpose extended mission being flown by the Deep Impact spacecraft. Yes, this is the same spacecraft that delivered an impactor to comet Tempel 1 with such spectacular results back in 2005. The vehicle now proceeds to a flyby of comet Hartley 2, but along the way a second extended mission has been coaxed out of it, this one targeting several known transiting planets in a search for signs of undiscovered worlds in those same systems. The mission will also look for possible moons or rings around the giant planets already discovered. Another goal: To study the Earth, by way of calibrating the kind of 'pale blue dot' imagery a future terrestrial planet finder might see. In fact, observations taking place this very day should be helpful because the Moon will 'transit' the Earth from the spacecraft's perspective. And yes, the nomenclature is confusing, but acronyms are the name of the game in space operations. EPOXI is actually a conflation of two...

Yesterday's high-tension arrival on Mars raises inescapable thoughts about future missions. Even the fastest spacecraft we can build today take years to reach the outer planets (New Horizons won't reach Pluto/Charon until 2015), and targets deep in the Kuiper Belt, much less the Oort Cloud, conjure up potential missions longer than a human lifetime. Imagine the arrival of a robotic interstellar probe around, say, Epsilon Eridani, not a few years after launch, but a few generations. How would the team feel that took that final handoff from previous researchers, people who had invested their lives in a mission whose end they knew they would never see? Thus we make the segue back into interstellar matters, with today's Phoenix operations still very much in mind. And I want to go quickly to the recent COROT announcement, for the doughty spacecraft has been hard at work observing its sixth star field, a sweep of some 12,000 stars that began in early May. The team presented two new planets...