Hubble and Chandra Discover Dark Matter Is Not as Sticky as Once Thought
In particle physics labs, like the Large Hadron Collider in Geneva, Switzerland, scientists smash atoms together to study the underpinnings of matter and energy. On the scale of the macrocosm, nature provides a similar experiment by crashing clusters of galaxies together. Besides galaxies and gas, the galaxy clusters contain huge amounts of dark matter. Dark matter is a transparent form of matter that makes up most of the mass in the universe. During collisions, the clouds of gas enveloping the galaxies crash into each other and slow down or stop. Astronomers found that the dark matter continued straight through the violent collisions, without slowing down relative to the galaxies. Their best explanation is that the dark matter did not interact with visible particles, and it also interacted less frequently with other dark matter than previously thought. Astronomers used the Hubble Space Telescope and Chandra X-ray Observatory to study 72 large galaxy cluster collisions. Chandra traced the hot gas, and Hubble saw how the invisible dark matter warps space and distorts the images of background stars. This allowed for the distribution of dark matter in the collision to be mapped. The finding narrows down the options for what this dark matter might be.
In 2007, Dutch schoolteacher Hanny van Arkel discovered a never-before-seen ghostly structure near a galaxy, while she was participating in an online amateur scientist project called Galaxy Zoo. The galaxy hosts a bright quasar that may have illuminated the apparition by hitting it with a beam of light from hot gas around a central black hole. Astronomers eagerly used the Hubble Space Telescope to do follow-up observations, which revealed knots of dust and gas in the "greenish blob." Assuming that this feature could offer insights into the puzzling behavior of active galaxies, Bill Keel of the University of Alabama, Tuscaloosa, initiated a search for other similar phenomenon. After all, where there's one strange blob there could be more. Keel had 200 volunteers look at archival data of 15,000 galaxies hosting quasars. In the end, he found eight other galaxies with bright active nuclei that have illuminated material far outside the radius of the galaxy. The eerie structures have looping, spiral, and braided shapes. Hubble's images show that they are like the remnants of galaxy collisions.
Hubble Space Telescope Celebrates 25 Years of Unveiling the Universe
NASA and ESA are celebrating the Hubble Space Telescope's silver anniversary of 25 years in space by unveiling some of nature's own fireworks – a giant cluster of about 3,000 stars called Westerlund 2. The cluster resides inside a vibrant stellar breeding ground known as Gum 29, located 20,000 light-years away in the constellation Carina. The comparatively young, 2-million-year-old star cluster contains some of our galaxy's hottest, brightest, and most massive stars. The largest stars are unleashing a torrent of ultraviolet light and hurricane-force winds that etch away the enveloping hydrogen gas cloud. This creates a fantasy celestial landscape of pillars, ridges, and valleys.
The universe is incredibly big. But how do astronomers know that? Billion-mile-long tape measures can't be found at the hardware store. Instead, astronomers use the expansion of the universe itself to establish milepost markers. The light from remote objects is attenuated and weakened as space stretches like a rubber band. The consequences are that starlight will look redder relative to a nearby star of the same temperature. When starlight is spread into its component color via spectroscopy, features in the light will be shifted to the red end of the spectrum. This "redshift" can be used to reliably calibrate distances. The challenge is the farthest objects in the universe are typically too faint for spectroscopy to work. So instead, astronomers deduce a galaxy's distance by precisely measuring its colors in visible and infrared light. This technique has found candidates for the farthest object in the universe.
Now, in a synergy between the Hubble and Spitzer space telescopes, and the giant W. M. Keck Observatory, astronomers have set a new distance record to the farthest redshift-confirmed galaxy. It is so far away the light we receive left the galaxy over 13 billion years ago, and it is just arriving now. Hubble found the galaxy in deep-sky surveys, and Keck's 10-meter-diameter segmented mirror is powerful enough to collect a spectrum from the unusually bright galaxy. The new observations underline the very exciting discoveries that NASA's James Webb Space Telescope will enable when it is launched in 2018.
Hubble Video Shows Shock Collision Inside Black Hole Jet
One of the trademarks of the Star Wars film episodes is the dreaded Death Star battle station that fires a beam of directed energy powerful enough to blow up planets. The real universe has such fireworks, and they are vastly more powerful than the Star Wars creation. These extragalactic jets are tearing across hundreds of light-years of space at 98 percent the speed of light. Instead of a battle station, the source of the killer beam is a supermassive black hole weighing many million or even a billion times the mass of our sun. Energy from the spinning black hole, and its titanic magnetic fields, shape a narrow jet of gas blasting out a galaxy's center. Hubble has been used over the past 25 years to photograph and rephotograph a jet blasting out the heart of the elliptical galaxy 3C 264 (also known as NGC 3862). Hubble's sharp vision reveals that the jet has a string-of-pearls structure of glowing knots of material. When these images were assembled into a time-lapse movie, they reveal – to the surprise of astronomers – a faster-moving bright knot rear-ending the bright knot in front of it. The resulting shock collision further accelerates particles that produce a focused beam of deadly radiation. The jet is moving so fast toward us it gives the illusion that it is traveling faster than the speed of light. But not to worry, the host galaxy is 260 million light-years away. We are seeing the jet as it looked before the dinosaurs appeared on Earth, and our planet was suffering a global mass extinction.
Quasars are the light fantastic. They are the brightest beacons in the universe, blazing across space with the intrinsic brightness of one trillion suns. Yet the objects are not vast galaxies, but they appear as pinpoint sources in the biggest telescopes of today – hence the term "quasar" for quasi-stellar object. Discovered in the 1960s, it took more than two decades of research to come to the conclusion that quasars are produced by the gusher of energy coming from over-fed supermassive black holes inside the cores of very distant galaxies. And, most quasars bloomed into a brief existence 12 billion years ago.
The big question has been, why? What was happening in the universe 12 billion years ago? The universe was smaller and so crowded that galaxies collided with each other much more frequently than today. Astronomers using Hubble's near-infrared vision tested this hypothesis by looking at dusty quasars where their glow was suppressed by dust, allowing a view of the quasar's surroundings. Hubble's sharp vision revealed chaotic collisions between galaxies that gave birth to quasars by fueling a supermassive central black hole.
NASA's Hubble Finds Evidence of Galaxy Star Birth Regulated by Black-Hole Fountain
Astronomers have long wondered how the universe's largest elliptical galaxies continue making stars long after their peak years of star birth. By combining data from NASA's Hubble Space Telescope with observations from a suite of ground-based and space telescopes, two independent teams have uncovered a unique process to explain how this star birth continues. The teams found that that the galaxy's central black hole, jets, and newborn stars are all parts of a self-regulating cycle. In that cycle, jets shooting out of the galaxy's center heat a halo of surrounding gas, controlling the rate at which it cools and falls into the galaxy. The astronomers used Hubble's high resolution and ultraviolet vision to resolve brilliant knots of hot, blue stars forming along the jets from active black holes in the centers of these giant galaxies.
NASA's Hubble Finds Supernovae in 'Wrong Place at Wrong Time'
What happens when you find something in the wrong place at the wrong time? That's a question astronomers have been trying to answer after finding several exploding stars outside the cozy confines of galaxies, where most stars reside. These wayward supernovae also have puzzled astronomers because they exploded billions of years before their predicted detonations. Astronomers using archived observations from several telescopes, including the Hubble Space Telescope, have developed a theory for where these doomed stars come from and how they arrived at their current homes.
According to their scenario, the supernovae were once stars in double-star systems that wandered too close to twin supermassive black holes at the core of a merging galaxy. The black-hole duo gravitationally catapulted the stars out of their home galaxies. The interaction pulled the stars closer together, which accelerated the merger between each pair. Eventually, the stars moved close enough to trigger a supernova blast.
Astronomers at the University of California at Irvine (UCI) and the Space Telescope Science Institute have made the most accurate statistical estimate of the number of faint, small galaxies that existed only 500 million years after the big bang. This was culled from an analysis of the deepest Hubble Space Telescope sky survey, CANDELS (Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey). Previously, studies using Caltech's CIBER (the Cosmic Infrared Background Experiment) rocket-borne instrument and NASA's Spitzer Space Telescope images confirmed the presence of "intra-halo light" from stars distributed outside of galaxies. The Hubble data found a new component in the infrared background in addition to intra-halo light – the collective glow of entire galaxies that formed first in the universe. UCI's Asantha Cooray believes that these early galaxies are very different from the well-defined spiral and disk-shaped galaxies seen in the present-day universe. They were more diffuse and populated by giant stars. This discovery paves the way for NASA's James Webb Space Telescope to see these very faint galaxies individually, after its launch in 2018.
Mysterious Ripples Found Racing Through Planet-Forming Disk
Though astronomers have discovered thousands of planets orbiting other stars, very little is known about how they are born. The conventional wisdom is that planets coagulate inside a vast disk of gas and dust encircling newborn stars. But the details of the process are not well understood because it takes millions of years to happen as the disk undergoes numerous changes until it finally dissipates.
The young, nearby star AU Microscopii (AU Mic) is an ideal candidate to get a snapshot of planet birthing because the disk is tilted nearly edge on to our view from Earth. This very oblique perspective offers an opportunity to see structure in the disk that otherwise might go unnoticed. Astronomers are surprised to uncover fast-moving, wave-like features embedded in the disk that are unlike anything ever observed, or even predicted. Whatever they are, these ripples are moving at 22,000 miles per hour – fast enough to escape the star's gravitational pull. This parade of blob-like features stretches farther from the star than Pluto is from our sun. They are so mysterious it's not known if they are somehow associated with planet formation, or some unimagined, bizarre activity inside the disk.
Hubble's Planetary Portrait Captures New Changes in Jupiter's Great Red Spot
Scientists using NASA's Hubble Space Telescope have produced new global maps of Jupiter – the first in a series of annual portraits of the solar system's outer planets from the Outer Planet Atmospheres Legacy program (OPAL). The two Jupiter maps, representing nearly back-to-back rotations of the planet on Jan. 19, 2015, show the movements of the clouds and make it possible to determine the speeds of Jupiter's winds. The Hubble observations confirm that the Great Red Spot continues to shrink and become more circular. In addition, an unusual wispy filament is seen, spanning almost the entire width of the vortex. These findings are described in a new paper published online in the October 10 issue of The Astrophysical Journal.
The collection of maps to be obtained over time from the OPAL program will not only help scientists understand the atmospheres of our giant planets, but also the atmospheres of planets being discovered around other stars.
Hubble Uncovers Fading Cinders of Some of Our Galaxy's Earliest Homesteaders
About 13 billion years ago, long before our sun formed, the construction of our Milky Way galaxy was just beginning. Young, mostly sun-like stars in the core, or central bulge, provided the building blocks for the galaxy's foundation. Many of these building-block stars have long since burned out, and are now just dying embers. But contained within these dead stars, called white dwarfs, is the early history of our galaxy, providing clues on how it came to be.
Finding these stellar relics, however, is a daunting task. Astronomers have had a difficult time picking out these dim objects from among the crowd of bright stars that fill the space between us and the core. Using Hubble Space Telescope images, astronomers have now conducted a "cosmic archaeological dig" of our Milky Way's heart, uncovering the blueprints of our galaxy's early construction phase. Hubble researchers have uncovered for the first time a population of ancient white dwarfs. The Hubble analysis represents the deepest, most detailed study of our galaxy's central bulge of stars.
NASA Space Telescopes See Magnified Image of the Faintest Galaxy from the Early Universe
Hunting for faraway galaxies that existed long, long ago is like a fishing trip for astronomers. So far only the "big fish" have been found, bright galaxies that existed just a few hundred million years after the big bang. Now, using the Hubble and Spitzer space telescopes, astronomers have caught a "smaller fish," a very compact and faint early galaxy that was forming 400 million years after the big bang, which happened 13.8 billion years ago.
As there are many smaller fish than big fish in the sea, the new finding is evidence for an underlying population of dim galaxies that must have been common in the early universe. Hubble's upcoming successor, the James Webb Space Telescope, should be able to survey this population. But for now, Hubble can do some pioneering work by exploiting a "zoom lens" in space that captures a galaxy that would otherwise not be detectible. The phenomenon is called gravitational lensing, where the intense gravity of a cluster of galaxies magnifies the light of fainter background sources. Astronomers needed the infrared sensitivity of both the Hubble and Spitzer telescopes to measure the galaxy's great distance through its color, which is affected by the expanding universe.
Caught in the Act: Hubble Captures First-Ever Predicted Exploding Star
Hubble has captured an image of the first-ever predicted supernova explosion. The reappearance of the supernova dubbed "Refsdal" was calculated by different mass models of a galaxy cluster whose immense gravity is warping the supernova's light as the light travels toward Earth. The supernova was previously seen in November 2014 behind the galaxy cluster MACS J1149.5+2223, part of Hubble's Frontier Fields program. Astronomers spotted four separate images of the supernova in a rare arrangement known as an Einstein Cross. This pattern was seen around a galaxy within MACS J1149.5+2223. While the light from the cluster has taken about five billion years to reach us, the supernova itself exploded much earlier, nearly 10 billion years ago. The detection of Refsdal's reappearance served as a unique opportunity for astronomers to test their models of how mass – especially that of mysterious dark matter – is distributed within this galaxy cluster.
NASA's Spitzer, Hubble Find 'Twins' of Superstar Eta Carinae in Other Galaxies
Eta Carinae, the most luminous and massive stellar system located within 10,000 light-years of Earth, is best known for an enormous eruption seen in the mid-19th century that hurled an amount of material at least 10 times the sun's mass into space. Still shrouded by this expanding veil of gas and dust, Eta Carinae is the only object of its kind known in our galaxy. Now a study using archival data from NASA's Spitzer and Hubble space telescopes has found five similar objects in other galaxies for the first time.
NASA's Hubble Space Telescope is an amazing time machine; by looking back through space, astronomers actually look back through time. Now, by pushing Hubble to its limits, an international team of astronomers has shattered the cosmic distance record by viewing the farthest galaxy ever seen. Named GN-z11, this surprisingly bright, infant galaxy is seen as it was 13.4 billion years in the past. The astronomers saw it as it existed just 400 million years after the big bang, when the universe was only three percent of its current age. At a spectroscopically confirmed redshift of 11.1, the galaxy is even farther away than originally thought. It existed only 200 million to 300 million years after the time when scientists believe the very first stars started to form. At a billion solar masses, it is producing stars surprisingly quickly for such an early time. This new record will most likely stand until the launch of Hubble's successor, the James Webb Space Telescope, which will look even deeper into the universe for early galaxies.
Telescopes Combine to Push Frontier on Galaxy Clusters
To learn more about galaxy clusters, including how they grow via collisions, astronomers have used some of the world's most powerful telescopes, looking at different types of light. They have focused long observations with these telescopes on a half-dozen galaxy clusters. The name for the galaxy cluster project is the "Frontier Fields." Two of these Frontier Fields galaxy clusters, MACS J0416.1-2403 (abbreviated MACS J0416) in the right panel and MACS J0717.5+3745 (MACS J0717 for short) in the left panel, are featured here in a pair of multiwavelength images.
Located about 4.3 billion light-years from Earth, MACS J0416 is a pair of colliding galaxy clusters that will eventually combine to form an even bigger cluster. MACS J0717, one of the most complex and distorted galaxy clusters known, is the site of a collision between four clusters. It is located about 5.4 billion light-years away from Earth. These new images of MACS J0416 and MACS J0717 contain data from three different telescopes: NASA's Chandra X-ray Observatory (diffuse emission in blue), Hubble Space Telescope (red, green, and blue), and the National Science Foundation's Karl G. Jansky Very Large Array (diffuse emission in pink). Where the X-ray and radio emission overlap the image appears purple. Astronomers also used data from the Giant Metrewave Radio Telescope in India in studying the properties of MACS J0416.
Imagine driving through a small town containing modest-sized buildings and seeing a 100-story skyscraper. Astronomers found the equivalent monstrosity in space: a near-record supermassive black hole that weighs 17 billion suns and lives in a cosmic backwater community of a few galaxies. Until now, extremely massive black holes have been found at the cores of very large galaxies in regions of the universe packed with other large galaxies. This is not just coincidence. Like a cosmic Pac-Man, a monster black hole gobbles smaller black holes when two galaxies collide. This game of bumper cars is common in large galaxy clusters. In fact, the current black hole record holder tips the scale at 21 billion suns and resides in the crowded Coma galaxy cluster, located 330 million light-years away.
The newly discovered supersized black hole resides in the center of a massive elliptical galaxy, NGC 1600, located in a small grouping of about 20 galaxies. Astronomers estimate that these smaller galactic groupings are about 50 times more abundant than spectacular galaxy clusters like the Coma cluster. Based on this discovery, astronomers are now asking, Is this the tip of an iceberg? Maybe there are more monster black holes out there that don't live in a skyscraper in Manhattan, but in a tall building somewhere in the Midwestern plains.
Twenty-six candles grace NASA's Hubble Space Telescope's birthday cake this year, and now one giant space "balloon" will add to the festivities. Just in time for the 26th anniversary of Hubble's launch on April 24, 1990, the telescope has photographed an enormous, balloon-like bubble being blown into space by a super-hot, massive star. Astronomers trained the iconic telescope on this colorful feature, called the Bubble Nebula, or NGC 7635. The bubble is 7 light-years across – about one-and-a-half times the distance from our sun to its nearest stellar neighbor, Alpha Centauri. The Bubble Nebula lies 7,100 light-years from Earth in the constellation Cassiopeia.
Hubble Catches Views of a Jet Rotating with Comet 252P/LINEAR
For thousands of years, humans have recorded sightings of mysterious comets sweeping across the nighttime skies. These celestial wanderers, "snowballs" of dust and ice, are swift-moving visitors from the cold depths of space. Some of them periodically visit the inner solar system during their journeys around the sun.
Astronomers using NASA's Hubble Space Telescope captured images of Comet 252P/LINEAR just after it swept by Earth on March 21. The visit was one of the closest encounters between a comet and our planet. The comet traveled within 3.3 million miles of Earth, or about 14 times the distance between our planet and the moon. The images reveal a narrow, well-defined jet of dust ejected by the comet's icy, fragile nucleus. The jet also appears to change direction in the images, which is evidence that the comets nucleus is spinning. The spinning nucleus makes the jet appear to rotate like the water jet from a rotating lawn sprinkler. These observations also represent the closest celestial object Hubble has observed, other than the moon. The comet will return to the inner solar system again in 2021.
