What exactly is the shock wave that Voyager 1 encountered earlier this year, a wave that is still propagating outward, according to new data from the craft? Researchers at the Jet Propulsion Laboratory refer to it as a 'tsunami wave,' a simile that reminds us of the devastating effects of roiled water as it encounters land following an earthquake or an impact in the ocean. But in this case the cause is a coronal mass ejection (CME), in which the Sun heaves out a magnetic cloud of plasma from its surface, generating a pressure wave. As this JPL news release explains, the outgoing wave runs into charged particles in deep space -- interstellar plasma -- creating the disturbance. In all, Voyager 1 has experienced three of these shock waves, with the most recent first being observed in February of 2014 and still continuing. The new data were presented on December 15 at the American Geophysical Union meeting in San Francisco by Don Gurnett (University of Iowa), who is quoted as saying...

What's ahead for exoplanet telescopes in space? Ashley Baldwin, who tracks today's exciting developments in telescope technology, today brings us a look at how a dark energy mission, WFIRST, may be adapted to perform exoplanet science of the highest order. One possibility is the use of a large starshade to remove excess starlight and reveal Earth-like planets many light years away. A plan is afoot to make starshades happen, as explained below. Dr. Baldwin is a consultant psychiatrist at the 5 Boroughs Partnership NHS Trust (Warrington, UK), a former lecturer at Liverpool and Manchester Universities and, needless to say, a serious amateur astronomer. by Ashley Baldwin Big things have small beginnings. Hopefully. Many people will be aware of NASA's proposed 2024 WFIRST mission. Centauri Dreams readers will also be aware that this mission was originally identified in the 2010 Decadal Survey roadmap as a mission with a $1.7 billion budget to explore and quantify "dark energy". As an...

Looking at the latest work from Carnegie’s Alan Boss reminds me once again of the crucial role computers play in astrophysical calculations. We’re so used to the process that we’ve come to take it for granted, but imagine where we’d be without the ability to model complex gravitational systems. To understand planet formation, we can simulate a protoplanetary disk around a young star and let a billion years pass in front of our eyes. And as our models improve, we can set the process in motion with ever greater fidelity. Read Caleb Scharf’s The Copernicus Complex ( Farrar, Straus and Giroux, 2014) to see how much we’ve learned by ever more precise modeling. Back in the late 1980s, Jacques Laskar (Bureau des Longitudes, Paris), Gerald Sussman and Jack Wisdom (the latter two at MIT) developed mathematical approaches that could track changes to orbital motions to understand our solar system’s past. Their work and the wave of innovation that followed helped us understand exponential...

Ashley Baldwin tracks developments in astronomical imaging with a passion, making him a key source for me in keeping up with the latest developments. In this follow-up to his earlier story on interferometry, Ashley looks at the options beyond the James Webb Space Telescope, particularly those that can help in the exoplanet hunt. Coronagraph and starshade alternatives are out there, but which will be the most effective, and just as much to the point, which are likely to fly? Dr. Baldwin, a consultant psychiatrist at the 5 Boroughs Partnership NHS Trust (Warrington, UK) and a former lecturer at Liverpool and Manchester Universities, gives us the overview, one that hints at great things to come if we can get these missions funded. by Ashley Baldwin Hubble is getting old. It is due to be replaced in 2018 by the much larger James Webb Space Telescope. This is very much a compromise of what is needed in a wide range of astronomical and cosmological specialties, one that works predominantly...

Surrounding the star HD100546, some 335 light years from Earth in the southern hemisphere constellation Musca (The Fly), is a cloud of gas and dust in the shape of a disk. The young star is 30 times brighter than the Sun and about 2.5 times as large. Sean Brittain (Clemson University) and team have now discovered a newly forming planet within the disk, one believed to be a gas giant about three times the size of Jupiter, 13 AU from the host star. They may also have discovered a circumplanetary disk around the newly forming planet. At work here is a technique called spectro-astrometry, about which a few words. Spectroscopic observations can tell us much about what is happening around young stars, producing data on their motion and helping to resolve close binaries. What becomes problematic with spectroscopy, though, is the need being to improve angular resolution and find ways around the problems created by observing through the Earth's atmosphere. We don't yet have the resolution to...

Science fiction writers have a new challenge this morning: To come up with a plot that takes in not just the galaxy and not just the Local Group in which the Milky Way resides, but the far larger home of both. Laniakea is the name of this supercluster, after a Hawaiian word meaning 'immense heaven.' And immense it is. Superclusters are made up of groups like the Local Group -- each of these contain dozens of galaxies -- and clusters that contain hundreds more, interconnected by a filamentary web whose boundaries have proven hard to define. Where does one supercluster begin and another end? As explained in a cover story in the September 4 issue of Nature, an emerging way to tune up our cosmic maps is to look at the effect of large-scale structures on the movements of galaxies. A team under R. Brent Tully (University of Hawaii at Manoa) has been using data from radio telescopes to study the velocities of 8000 galaxies, adjusting for the universe's accelerating expansion to create a map...

I have a soft spot in my heart for the Green Bank Telescope in West Virginia. It's not just that Frank Drake started Project Ozma on the site in 1960, or that Benjamin Zuckerman and Patrick Palmer ran an Ozma follow-up there in the mid-1970s. I was tracking SETI closely by 1980 or so and knew of these observations, but it was my friend Mike Gingell whose yearly trips to Green Bank kept the place firmly in mind. Like me, Mike was a member of the Society of Amateur Radio Astronomers, and unlike me, he was a highly qualified engineer. Mike died just last year and I went out to his house to look through a collection of old radio books his wife thought I might be interested in. There in the back yard were three radio dishes, all tuned not for television but for the radio astronomy work Mike was so engaged in. Seeing them already beginning to succumb to foliage -- Mike had been ill for some time and couldn't keep up with them -- reminded me strongly of some of J.G. Ballard's fiction, like...

The recent news that the Stardust probe returned particles that may prove to be interstellar in origin is exciting because it would represent our first chance to study such materials. But Stardust also reminds us how little we know about the interstellar medium, the space beyond our Solar System's heliosphere through which a true interstellar probe would one day travel. Another angle into the interstellar medium is being provided by new maps of what may prove to be large, complex molecules, maps that will help us understand their distribution in the galaxy. The heart of the new work, reported by a team of 23 scientists in the August 15 issue of Science, is a dataset collected over ten years by the Radial Velocity Experiment (RAVE). Working with the light of up to 150 stars at a time, the project used the UK Schmidt Telescope in Australia to collect spectroscopic information about them. The resulting maps eventually drew on data from 500,000 stars, allowing researchers to determine...

In interstellar terms, a 'fast' mission is one that is measured in decades rather than millennia. Say for the sake of argument that we achieve this capability some time within the next 200 years. Can you imagine where we'll be in terms of telescope technology by that time? It's an intriguing question, because telescopes capable of not just imaging exoplanets but seeing them in great detail would allow us to choose our destinations wisely even while giving us voluminous data on the myriad worlds we choose not to visit. Will they also reduce our urge to make the trip? Former NASA administrator Dan Goldin described the effects of a telescope something like this back in 1999 at a meeting of the American Astronomical Society. Although he didn't have a specific telescope technology in mind, he was sure that by the mid-point of the 21st Century, we would be seeing exoplanets up close, an educational opportunity unlike any ever offered. Goldin's classroom of this future era is one I'd like...

Space dust collected by NASA's Stardust mission, returned to Earth in 2006, may be interstellar in origin. We can hope that it is, because the Solar System we live in ultimately derives from a cloud of interstellar gas and dust, so finding particles from outside our system takes us back to our origins. It's also a first measure -- as I don't have to tell this audience -- of the kind of particles a true interstellar probe will encounter after it has left our system's heliosphere, the 'bubble' in deep space blown out by the effects of the Sun's solar wind. Image: Artist's rendering of the Stardust spacecraft. The spacecraft was launched on February 7, 1999, from Cape Canaveral Air Station, Florida, aboard a Delta II rocket. It collected cometary dust and suspected interstellar dust and sent the samples back to Earth in 2006. Credit: NASA JPL. The cometary material has been widely studied in the years since its return, but how to handle the seven potentially interstellar grains thus far...

Our recent discussions of the latest awards from the NASA Innovative Advanced Concepts office remind me that you can easily browse through the older NIAC awards online. But first a word about the organization's history. NIAC operated as the NASA Institute for Advanced Concepts until 2007 under the capable leadership of Robert Cassanova, who shepherded through numerous studies of interest to the interstellar-minded, from James Bickford's work on antimatter extraction in planetary magnetic fields to Geoffrey Landis' study of advanced solar and laser lightsail concepts. The NIAC Funded Studies page is a gold mine of ideas. NIAC has been the NASA Innovative Advanced Concepts office ever since 2011, when the program re-emerged under a modified name. NASA's return to NIAC in whatever form was a welcome development. Remember that we had lost the Breakthrough Propulsion Physics project in 2002, and there was a time there when the encouragement of ideas from outside the agency seemed...

Remember Robert Forward's beamed sail concepts designed for travel to another star? Forward was the master of thinking big, addressing questions of physics which, once solved, left it up to the engineers to actually build the enormous infrastructure needed. Thus his crewed mission to Epsilon Eridani, which would demand not only a large power station in the inner system but a huge Fresnel lens out between the orbits of Saturn and Uranus. A 75,000 TW laser system was involved, a 'staged' sail for deceleration at the destination, and as for that lens, it would mass 560,000 tons and be a structure at least a third the diameter of the Moon. In addition to being a highly regarded physicist, Forward was also a science fiction writer who detailed his beamed sail concepts in Rocheworld (Baen, 1990), which grew out of a previous version in Analog. I always thought of the Epsilon Eridani mission as his greatest attempt to confound human engineering, but later came to think that vast structures...

Not long ago we talked about what the Milky Way would look like when seen from afar. I had mentioned Poul Anderson's World Without Stars, which appeared in Analog in 1966 under the title The Ancient Gods. In the Anderson tale, a starship crew is sent to make contact with a recently discovered technological civilization that lives on a world hundreds of thousands of light years from the galactic core. Now a recent paper deepens our understanding of this environment deep in the galaxy's outer halo. Recall that the Milky Way is about 100,000 light years in diameter, and that the distance to the nearest large galaxy is roughly 2,500,000 light years. Anderson's crew is over 200,000 light years from the core, which puts them in the outer halo, a sparse spherical volume of space that stretches out 500,000 light years, well beyond the familiar, highly visible disk. While the stars in the galactic disk are on nearly circular orbits in the plane of the galaxy, the halo stars are on more...

Growing up in the American Midwest, I used to haunt the library in Kirkwood, Missouri looking for books on astronomy. I had it in mind to read all of them and I pretty much did, looking with fascination at fuzzy images of distant objects I yearned to see close up. What did Saturn look like from Titan? What would it be like to be close enough to see the Crab Nebula fill the sky? Breathtakingly, what would it look like to be inside one of the great globular clusters? Early on in Vernor Vinge’s A Fire Upon the Deep the character Ravna finds herself looking out a window at the entire Milky Way from a distance sufficient to view it whole: She’d guessed right: tonight the Galaxy owned the sky… Without enhancement, the light was faint. Twenty thousand light-years is a long, long way. At first there was just a suggestion of mist, and an occasional star. As her eyes adapted, the mist took shape, curving arcs, some places brighter, some dimmer. A minute more and … there were knots in the mist...

We've been looking at not just interstellar but intergalactic crossings in the past few days, something of an homage to Carl Sagan, whose enthusiasm for continuous acceleration at 1 g and relativistic time dilation was immense in the years shortly after Robert Bussard's key paper on interstellar ramjets. Without a working ramjet and largely unaided by time dilation, we're faced with millions of years of flight time to reach M31. What to do? In a recent paper, discussed here by Adam Crowl on Monday, Robin Spivey ponders 'autonomous probes that spawn life upon arrival' as a way of reaching the Virgo cluster, which he wants to do for reasons Adam explained in his post. He's also counting on continuous acceleration at 1 g for these small 'seed ships,' but other than mentioning antimatter, he doesn't explore how this would be done, and we've seen the results Sagan and Iosif S. Shklovskii came up with for antimatter when they worked out the equations. Let's assume that the 'slow boat'...

We have several months yet before the European Space Agency's Gaia mission enters its five-year operational phase. But you can see an important milestone in the image below. Gaia's two telescopes have to be aligned and focused as its other instruments are calibrated. Testing involves downloading data like this image of NGC1818, a young star cluster in the Large Magellanic Cloud. The image covers an area something less than one percent of the spacecraft's full field of view. Launched on December 19, 2013, Gaia now orbits around the L2 Lagrangian point some 1.5 million kilometers from Earth. Image: A calibration image from Gaia is part of early testing of the mission's systems. Credit: ESA/DPAC/Airbus DS. Gaia inevitably makes me think of Hipparcos, an earlier ESA mission launched in 1989 devoted to precision astrometry, the measurement of proper motions and parallaxes of stars to help us figure out their distance and tangential velocity. What a far cry Hipparcos was from the days when...

NGC 6946, the so-called 'Fireworks Galaxy,' has caught the eye of many an astronomer, even if its position -- close to the plane of the Milky Way and thus partially obscured by gas and dust -- makes the observation difficult. At 22 million light years from Earth, this face-on spiral galaxy has been the site of eight supernovae in the past century. I'm thinking about supernovae because SN 2014J, a supernova a scant 12 million light years away in M82, has been much in the news in recent days. But NGC 6946 is also intriguing because of the active pace of star formation there. What sustains a galaxy like this and keeps its star formation robust? Image: The spiral galaxy NGC 6946. Observations from the Chandra spacecraft have revealed three of the oldest supernovas ever detected in X-rays here. This composite image also includes optical data from the Gemini Observatory in red, yellow, and cyan. Credit: X-ray: NASA/CXC/MSSL/R.Soria et al, Optical: AURA/Gemini OBs. Now D. J. Pisano (West...

Couple the Keck I 10-meter telescope on Mauna Kea with HIRES (the High-Resolution Echelle Spectrometer) and you get extremely high spectral resolution, making the combination a proven champion at finding planets around other stars. But it was when Justin Crepp (University of Notre Dame) and team followed up seventeen years of HIRES measurements with new observations using NIRC2 (the Near-Infrared Camera, second generation), mounted on the Keck II telescope with adaptive optics, that a nearby brown dwarf could be directly imaged. HD 19467 B is a T-dwarf more than 100,000 times fainter than its host, a nearby star whose distance (roughly 101 light years) is well established. The team believes the discovery will allow scientists to establish benchmarks that will help define objects with masses between stars and planets. Says Crepp: "This object is old and cold and will ultimately garner much attention as one of the most well-studied and scrutinized brown dwarfs detected to date. With...

The supermassive black hole at the center of our galaxy comes to Centauri Dreams' attention every now and then, most recently on Friday, when we talked about its role in creating hypervelocity stars. At least some of these stars that are moving at speeds above galactic escape velocity may have been flung outward when a binary pair approached the black hole too closely, with one star being captured by it while the other was given its boost toward the intergalactic deeps. At a mass of some four million Suns, Sagittarius A* (pronounced 'Sagittarius A-star') is relatively quiet, but we can study it through its interactions. And if scientists at the University of Michigan are right, those interactions are about to get a lot more interesting. A gas cloud some three times the mass of the Earth, dubbed G2 when it was found by German astronomers in 2011, is moving toward the black hole, which is 25,000 light years away near the constellations of Sagittarius and Scorpius. What's so unusual...

How do you boost the velocity of a star up to 540 kilometers per second? Somewhere in that region, with a generous error range on either side, is the speed it would take to escape the galaxy if you left from our Solar System's current position. Here on Centauri Dreams we often discuss exotic technologies that could propel future vehicles, but it's hard to imagine mechanisms that would drive natural objects out of the galaxy at such speeds. Even so, there are ways, as explained by Vanderbilt University's Kelly Holley-Bockelmann: "It's very hard to kick a star out of the galaxy. The most commonly accepted mechanism for doing so involves interacting with the supermassive black hole at the galactic core. That means when you trace the star back to its birthplace, it comes from the center of our galaxy." The mechanism works like this: A binary pair of stars moving a bit too close to the massive black hole at the center of the Milky Way loses one star to the black hole while flinging the...