We rarely talk about Teegarden's Star when mentioning interesting objects near the Solar System, probably because the star was only discovered in 2003 and until now had not been known to host planets. Today we learn, however, that an international team led by the University of Göttingen has found two planets close to Earth mass in what it considers to be the habitable zone around the tiny star. Interestingly, from where the system is located, any local astronomers would be able to see the planets of our Solar System in transit across the face of the Sun, about which more in a moment. One of the reasons that this comparatively nearby star has been so late to be discovered is its size. We are dealing with an M-class red dwarf, this one in the constellation Aries, and no more than 12.5 light years from us. It took three years of patient radial velocity monitoring to track down planets around a star that is only about 2700 degrees Celsius in temperature, and fully 10 times lighter than...

We’re getting first results from the Gemini Planet Imager Exoplanet Survey (GPIES), a four-year look at 531 young, nearby stars that relies on the instrument’s capabilities at direct imaging. Data from the first 300 stars have been published in The Astronomical Journal, representing the most sensitive, and certainly the largest direct imaging survey for giant planets yet attempted. The results of the statistical analysis are telling: They suggest that planets slightly more massive than Jupiter in outer orbits around stars the size of the Sun are rare. The Gemini Planet Imager (GPI), located at the Gemini South Telescope in Chile, can achieve high contrast at small angular separations, making it possible to see exoplanets directly, as opposed to the indirect methods that have dominated the field, such as transits and radial velocity analysis. As successful as the latter have been, they are most effective with planets closer to their stars, whereas an instrument like the GPI can find...

We're on the cusp of exciting developments in exoplanet detection, as yesterday's post about the Near Earths in the AlphaCen Region (NEAR) effort makes clear. Adapting and extending the VISIR instrument at the European Southern Observatory's Very Large Telescope in Chile, NEAR has seen first light and wrapped up its first observing run of Centauri A and B. What it finds should have interesting ramifications, for its infrared detection capabilities won't find anything smaller than twice the size of Earth, meaning a habitable zone discovery might rule out a smaller, more Earth-like world, while a null result leaves that possibility open. The NEAR effort relies on a coronagraph that screens out as much as possible of the light of individual stars while looking for the thermal signature of a planet. An internal coronagraph is one way to block out starlight (the upcoming WFIRST -- Wide Field Infrared Survey Telescope -- mission will carry a coronagraph within the telescope), but starshade...

I marvel that so many of the big questions that have preoccupied me during my life are starting to yield answers. Getting New Horizons to Pluto was certainly part of that process, as a mysterious world began to reveal its secrets. But we're also moving on the Alpha Centauri question. We have a habitable zone planet around Proxima, and we're closing on the orbital space around Centauri A and B, a G-class star like our Sun and a cooler K-class orange dwarf in a tight binary orbit, the nearest stars to our own. At the heart of the research is an instrument called a thermal infrared coronagraph, built in collaboration between the European Southern Observatory and Breakthrough Watch, the privately funded attempt to find and characterize rocky planets around not just Alpha Centauri but other stars within a 20 light year radius of Earth. The coronagraph blocks out most of the stellar light while being optimized to capture the infrared frequencies emitted by an orbiting planet. Note that...

We've been looking at circumstellar disks for quite some time, and teasing out images of actual planets within them, as witness HR 8799, where four exoplanets have been found. Just recently we saw imagery of a second world around PDS 70, both planets seen by direct imaging as they plowed through the disk of dust and gas surrounding a young star. All told, we now have more than a dozen exoplanets that have been directly imaged, though only two are in multi-planet systems. PDS 70b is sweeping out an observable gap in the disk. Image: PDS 70 is only the second multi-planet system to be directly imaged. Through a combination of adaptive optics and data processing, astronomers were able to cancel out the light from the central star (marked by a white star) to reveal two orbiting exoplanets. PDS 70 b (lower left) weighs 4 to 17 times as much as Jupiter while PDS 70 c (upper right) weighs 1 to 10 times as much as Jupiter. Credit: ESO and S. Haffert (Leiden Observatory). Now we learn that...

The Moon’s farside used to be a convenient setting for wondrous things. After all, no one had ever seen it, setting the imagination free to insert everything from paradisaical getaways (think Shangri-La in space) to secret technologies or alien civilizations. The Soviet Luna 3 image of 1959 took the bloom off that particular rose, but we also learned through this and subsequent missions that farside really does have its differences from the familiar face we see. More craters, for one thing, and fewer of the dark plains we call maria, or ‘seas.’ We can throw in measurements made by the GRAIL mission (the Gravity Recovery and Interior Laboratory) in 2012. GRAIL was a NASA Discovery-class mission that performed gravitational field mapping of the Moon as a way of examining its internal structure, a set of two probes that worked by analyzing measured changes in distance between the two craft as small as one micron. We wound up with a map of our satellite’s gravitational field that led to...

We should be glad to run into the unexpected when doing research, because things we hadn't foreseen often point to new understanding. That's certainly the case with infant planetary systems as observed through the circumstellar disks of gas and dust surrounding young stars. ALMA (the Atacama Large Millimeter/submillimeter Array) has been central to the study of such targets. An array of 66 radio telescopes in Chile's Atacama Desert, the facility works at millimeter and submillimeter wavelengths to provide detailed imaging of emerging systems. Because it has been revealing a variety of small-scale structures within circumstellar disks, ALMA is giving us insights into planet formation as we observe gaps, rings and spiral arms and their interactions with young planets. This is where the unexpected comes in. For researchers looking at a 5 million year old star called HD 163296 are seeing an unusual amount of dust, more than 300 times the mass of the Earth, despite the detection of at...

A planet labeled NGTS-4b has turned up in a data space where astronomers had not expected it, the so-called ‘Neptunian desert.’ Three times Earth radius and about 20 percent smaller than Neptune, the world was discovered with data from the Next-Generation Transit Survey (NGTS), which specializes in transiting worlds around bright stars, by researchers from the University of Warwick. It turns out to be a scorcher, with temperatures in the range of 1,000 degrees Celsius. NGTS-4b is 20 times as massive as the Earth, and its orbit takes it around its star, a K-dwarf 920 light years out, every 1.3 days. The planet is getting attention not so much because of what it is but where it is. Lead author Richard West (University of Warwick) comments: "This planet must be tough - it is right in the zone where we expected Neptune-sized planets could not survive. It is truly remarkable that we found a transiting planet via a star dimming by less than 0.2% - this has never been done before by...

I’m always interested in hearing about new ways to mine our abundant datasets. Who knows how many planets may yet turn up in the original Kepler and K2 data, once we’ve applied different algorithms crafted to tease out their evanescent signatures. On the broader front, who knows how long we’ll be making new discoveries with the Cassini data, gathered in such spectacular fashion over its run of orbital operations around Saturn. And we can anticipate that, locked up in archival materials from our great observatories, various discoveries still lurk. Assuming, of course, we know how to find them and, just as important, how to confirm that we’re not just looking at noise. What scientists at the Max Planck Institute for Solar System Research (MPS), the Georg August University of Göttingen, and the Sonneberg Observatory have come up with is 18 new planets roughly of Earth size that they’ve dug out of K2, looking at 517 stars that, on the basis of earlier analysis, had already been...

In a white paper submitted to the Decadal Survey on Astronomy and Astrophysics (Astro2020), Philip Horzempa (LeMoyne College) suggests using technology originally developed for the NASA Space Interferometry Mission (SIM), along with subsequent advances, in a mission designed to exploit astrometry as an exoplanet detection mode. I'm homing in on astrometry itself in this post rather than the mission concept, for the technique may be coming into its own as an exoplanet detection method, and I'm interested in new ways to exploit it. Astrometry is all about refining our measurement of a star's position in the sky. When I talk to people about detecting exoplanets, I find that many confuse astrometry with radial velocity, for in loose explanatory terminology, both refer to measuring the 'wobble' a planet induces on a star. But radial velocity examines Doppler effects in a star's spectrum as the star moves toward and then away from us, while astrometry looks for tiny changes in the position...