Life and pulsars don't seem to mix. But science fiction hasn't shied away from making the connection, as witness Robert Forward's Dragon's Egg (Ballantine, 1980). In the novel, a species called the cheela live on the surface of a neutron star, coping with a surface gravity 67 billion times stronger than that of Earth. An interesting consequence: The cheela live at an accelerated rate, going from the development of agriculture to high-tech in little more than a month, as perceived by the human crew observing the course of their rapid development. Now we have news that two astronomers are considering habitable planets in orbits around pulsars, a venue that to my knowledge Forward never considered, but perhaps more recent science fiction writers have (let me know if you have any references). Alessandro Patruno (Leiden University), working with Mihkel Kama (Leiden and Cambridge University) see reasons for thinking that life might emerge in such an environment, though the kind of...

One of the reasons to pay attention to spectrograph technologies -- and we recently talked about ESPRESSO, which has just achieved ‘first light’ -- is that we’re reaching the inflection point when it comes to certain key observations. Finding planets around Centauri A and B has been the gold standard for a number of researchers, and as Debra Fischer (Yale University) points out, we’re just now getting to where spectrographic technology is up to the challenge. Chile is where much of the action is. Here we find ESPRESSO installed on the European Southern Observatory’s Very Large Telescope at Paranal. But Fischer’s team has built CHIRON at Cerro Tololo, and the paper likewise relies on data from the Geneva team’s HARPS and the UVES installation at the Very Large Telescope Array in the United States. Working with Yale’s Lily Zhao, Fischer has re-examined older data with an eye toward turning once again to Centauri A and B with a new round of observations beginning the year after next....

Any thought that our Solar System offers a template for other stellar systems has pretty much vanished in the panoply of system architectures now exposed to our observation. But it seemed rational, in the days before we knew of the existence of other systems, to imagine that if they were there, they would be more or less well ordered. Planets presumably orbited in the equatorial plane of their star, all more or less co-planar (and if Pluto didn't quite fit the bill, that was just more evidence of the features that would one day cause it to become a 'dwarf planet'). But looking at the eight planets that remained after Pluto's 'demotion,' we see planets that are co-planar within about 7 degrees of difference. And as Ethan Siegel (Lewis & Clark College) points out, if we take Mercury out of the mix, the deviation from the plane is only about two degrees (Mercury's inclination is 7 degrees). Likewise, planets in our system line up well with the Sun's rotation axis. But some systems...

NASA's news conference announcing the discovery of Kepler-90i and Kepler-80g was a delightful validation of a principle that has long fascinated me. We have such vast storehouses of astronomical data that finding the time for humans to mine them is deeply problematic. The application of machine learning via neural networks, as performed on Kepler data, shows what can be accomplished in digging out faint signals and hitherto undiscovered phenomena. Specifically, we had known that Kepler-90 was a multi-planet system already, the existing tools -- human analysis coupled with automated selection methods -- having determined that there were seven planets there. Kepler-90i emerged as a very weak signal, and one that would not have made the initial cut using existing methods of analysis. When subjected to the machine learning algorithms developed by Google's Christopher Shallue and Andrew Vanderburg (UT-Austin), the light curve of Kepler-90i as well as that of Kepler-80g could be...

Until we can start observing the atmospheres of rocky worlds around red dwarf stars, we're left to extrapolate conditions there as best we can. New work discussed at the fall meeting of the American Geophysical Union on Dec. 13 recounts one such attempt, using the planet Mars as a surrogate for a similar world in habitable zone orbit around an M-dwarf. The work draws on data from the MAVEN (Mars Atmosphere and Volatile Evolution) mission, launched in 2013 and now orbiting the Red Planet. Designed to study the deterioration of its atmosphere over time, MAVEN offers insights into exoplanets that are derived from plugging in different stellar values. Image: To receive the same amount of starlight as Mars receives from our Sun, a planet orbiting an M-type red dwarf would have to be positioned much closer to its star than Mercury is to the Sun. Credit: NASA/GSFC. MAVEN co-investigator David Brain (University of Colorado, Boulder) discussed MAVEN data at the meeting, noting that the planet...

The transiting red dwarf K2-18 is about 111 light years out in the general direction of the constellation Leo, with a mass of 40 percent of Sol’s. A super-Earth, K2-18b, was detected here in 2015 through light curve analysis of data from the reconfigured Kepler K2 mission, and we now have the first measurement of the planet’s mass, drawing on radial velocity data from HARPS. The two planet detection methods in conjunction thus firm up our knowledge of a possible habitable zone planet. But they also reveal, in the analysis of Ryan Cloutier (University of Toronto) and colleagues, a second super-Earth, K2-18c, which turns out to be non-transiting, and therefore non-coplanar with K2-18b. As we saw yesterday, HARPS (High Accuracy Radial Velocity Planet Searcher), is capable of drilling down to about one meter per second in the analysis of the stellar wobbles that radial velocity methods examine. The current data set gives us another interesting world while reminding us of the capabilities...

What great news that ESPRESSO, the Echelle SPectrograph for Rocky Exoplanet and Stable Spectroscopic Observations, has just achieved 'first light.' The spectrograph is installed on the European Southern Observatory's Very Large Telescope at the Paranal Observatory in northern Chile and its powers are prodigious. For ESPRESSO makes it possible, for the first time, to combine the light of all four telescopes at the VLT. This creates an instrument with the light collecting power of a 16-meter telescope, a major enhancement to the exoplanet hunt. Image: The room where the light beams coming from the four VLT Unit Telescopes are brought together and fed into fibres, which in turn deliver the light to the spectrograph itself in another room. One of the points where the light enters the room appears at the back of this picture. Credit: ESO/P. Horálek. Thus the enthusiasm of lead scientist Francesco Pepe (University of Geneva): ESPRESSO isn't just the evolution of our previous instruments...

Why all the fuss about red dwarf planets? We're seeing so much ongoing work on these worlds because when it comes to terrestrial-class planets -- in size, at least -- those around red dwarfs are going to be our first targets for atmospheric characterization. A 'habitable zone' planet around a red dwarf throws a deep transit signature -- small star, big planet -- so that we can use transit spectroscopy to puzzle out atmospheric components. Getting an actual image would be even better, and modifications to the VISIR instrument at ESO's Very Large Telescope, a project Breakthrough Initiatives is involved in along with the ESO, could eventually yield such. We'll know a great deal more about the possibilities as new missions come online, but for now, researchers are doing their best to apply models to what we know and deduce what surface conditions may be like around stars like TRAPPIST-1 and Proxima Centauri. Some of these results are not auspicious if it's life we're looking for. I'm...

TRAPPIST-1 and its seven interesting planets may be the most compelling stellar system we're investigating, given the range of worlds here and the possibilities for analyzing an entire, nearby planetary system. But as we look toward examining systems like this with new space- and ground-based instruments, we may run into problems with searching for biosignatures. Both the TRAPPIST-1 planets and the promising Proxima Centauri b may be tough to characterize. The problem: When searching for biosignatures, we're looking for signs of metabolism, gases that are continually produced and remain out of balance in a planetary atmosphere. Ozone is one piece of the puzzle, one that signifies oxygen. Finding the latter in the same atmosphere with methane would be a compelling biosignature. But ozone could be hard to detect. Ludmila Carone (Max Planck Institute for Astronomy) and colleagues now find that atmospheric circulation in planets close enough to red dwarfs to be in their habitable zone...