Scientists have captured their best view yet of how extreme magnetic fields shape superfast jets from the most powerful explosions in the universe.
The new research tracked polarized light from cosmic explosions, known as gamma-ray bursts, and offered an unprecedented glimpse into how intense magnetic fields shape the evolution of the outbursts.
“Gamma-ray bursts are the most extreme particle accelerators in the universe,” said Carole Mundell, a professor of extragalactic astronomy at Liverpool John Moores University, who led the new study. “They’re objects of all kinds of extremes: extreme speeds, extreme gravity, extreme magnetic fields. So they’re the ultimate laboratory for testing or laws of physics.” [10 Strangest Things in Space]
Gamma-ray bursts are believed to form at the end of a massive star’s life, just as the body of the star collapses in on itself, creating a black hole. As this happens, the matter surrounding the black hole may release two jets of gamma-rays and highly energetic particles, in opposite directions away from the black hole. A single gamma-ray burst may radiate more energy in a few minutes than the star radiated in its entire lifetime.
Mysterious origins of cosmic explosions
Scientists still don’t understand how the particles surrounding a black hole can generate the intense bursts of light and particles seen in gamma-ray bursts.
One theory suggests that an organized magnetic field will accelerate particles on an invisible track around the black hole, causing them to radiate light (what’s known as synchrotron radiation). As the black hole rapidly contracts, so do the particles and the magnetic field, causing the particles to accelerate even faster. The theory suggests that it is this rapid bump in acceleration, combined with energy stored in the particles themselves, that creates two massive jets of gamma-rays and particles.
If the energy in a gamma-ray burst was at least partly due to synchrotron radiation, then scientists could expect to see an imprint of that magnetic field in the light produced by this violent event.
New telescope tool’s magnetic find
Mundell and her colleagues designed an instrument named RINGO2 to measure the polarization of optical light that is produced as a byproduct of a gamma-ray burst. RINGO2 observed gamma-ray bursts for two years on the Liverpool optical telescope.
On March 8, 2012, NASA’s Swift satellite — which tracks gamma-ray bursts — alerted the Liverpool telescope to a cosmic explosion dubbed GRB 120308A. The subsequent study, which was detailed in the Dec. 5 edition of the journal Nature, found that optical light emitted early on by GRB 120308A was 28 percent polarized, and decreased to 10 percent polarization over time.
“If you take optical light and you scatter it from dust, as it comes through our Milky Way galaxy, you might observe a few percent polarization,” Mundell said. “Really the only way to produce this high degree of polarization is to have large-scale ordered magnetic fields that are producing the synchrotron radiation with the electrons spiraling around the magnetic field.”
Mundell said the reduction in the polarization of the light over time demonstrates that the light is polarized upon its creation near the black hole, and loses its polarization as it travels through space. For this reason, RINGO2 must observe the optical light almost immediately after the start of the gamma-ray burst, in order to observe the polarity.
More observations of polarized light in future gamma-ray bursts are needed to confirm the findings, the researchers said. RINGO2 operated on the Livermore telescope for two years and collected data on multiple gamma-ray bursts.
“We’re in the process of working on a sample paper about those other gamma-ray bursts,” Mundell said. “Obviously, we want to look at more of them and really prove that this is a universal case and not just a special object. [GRB 120308A] wasn’t special in any other way, and that’s one good reason to suggest that it was typical.”
With the second spacecraft this month now on its way to Mars, you could be forgiven for thinking we’ve forgotten that there is a number of other planets in our solar system.
Due to arrive in orbit about the red planet in September 2014, MAVEN will be the first probe to explore the upper reaches of the Martian atmosphere. It will do this by taking a number of dives into the upper atmosphere, dipping to only 125 km about the Martian surface from its home orbit of 6,000 km.
The hope is that to find clues to a possible warmer and wetter past.
But with Opportunity still trundling along, Curiosity, the Mars Orbiter Mission, MAVEN, the Mars Reconnaissance Orbiter, Mars Express, 2001 Mars Odyssey and the planned InSight, ExoMars and Mars 2020 rover missions, are we forgetting that there’s more to the solar system than Mars?
Sure it is the most viable planet that we, the human race, could go and walk on but it’s probably not the best hope for the discovery of biological activity.
Don’t get me wrong, I’m a massive fan of any space mission, and every step we make in space is a “giant” leap for us down here on Earth. Every endeavour we have undertaken on Mars has thrown up yet more intrigue, and we’ve barely scratched the surface.
But let’s not kid ourselves; it looks pretty dead up there. If we do find any biology on Mars, it going to be most interesting working out how it has hung on for billions of years (and try and get some survival tips).
I admit “The Mars Overload” is a bit of misrepresentation, as we are currently exploring (or travelling to) pretty much every other planet in our solar system right now (with two notable exceptions). So what are they all up to?
The Messenger craft is currently 3,400 days into its mission in orbit about Mercury, and has now imaged the whole surface of the Sun’s closest neighbour. It’s currently in a bit of a limbo, with it’s extended mission finishing in March this year.
Venus currently has the European Space Agency’s Venus Express spacecraft in orbit and the Japanese mission Akatsuki hopefully en route. Venus Express has returned the strongest indications yet that Venus is geologically active, and if confirmed would be the first planets (other than our own Earth) to be discovered so.
Akatsuki, which was planning to study Venus’ extreme climate, unfortunately failed to insert into Venutian orbit in 2010. But hope is not lost, and it is currently held in an elliptical orbit with plans to make another attempt into a closer orbit in 2015.
The asteroid belt
The asteroid belt is the museum of the solar system, and the Dawn mission has been the first to traverse it and focus on some of its biggest exhibits. Dawn’s first stop was orbiting about the asteroid Vesta, and has now left to journey to the largest body in the belt – Ceres – due to arrive in 2015.
At Vesta, Dawn discovered this body’s large metallic core revealing it to be the “last of its kind” as a failed planet.
Any mission to Jupiter has a lot to live up to, with the enduring data set that the Galileo spacecraft collected, coupled with its dramatic ending.
The Juno mission is currently on its way, arriving in 2016 will concentrate on the gas giant’s poles and magnetic and gravity field. The hope that such a detailed mission will reveal more about our largest neighbours interior.
On the cards is more of a successor of Galileo, the European Space Agency’s JUICE mission. But we’re playing the waiting game on this one – with arrival at Jupiter not anticipated to be before 2030.
The most longstanding of current planetary missions is Cassini, launched in 1997. It’s currently in the second phase of its mission and has performed a Galileo-like job on Saturn, returning data on the planet, its rings and moons that will be mulled over for decades.
Like Messenger, is waiting confirmation of its next extended mission, which will keep it running until 2017.
There has been worrying news that cuts to NASA’s budget will force them to choose between extending Cassini or the Mars-roving Curiosity. A terrible choice by all accounts, but given the massive effort taken to get Cassini out there, I really hope that there is some way of keeping them both going.
New Horizons is going to be a science highlight of 2015 when it arrives at the far reaches of our solar system to study Pluto. Since it was launched in 2006 it has seen it’s primary target kicked out of the planet club, but promoted to be the “king” of the dwarf planets.
New Horizons will pass Pluto and it’s companion Charon before heading deeper into the Kuiper belt. Being the first probe to explore this new class of planets in detail, it’s almost guaranteed to return some very exciting stuff.
And the rest …
Uranus and Neptune are the notable exceptions. These gassy icy giants still lie pretty much unexplored with humankind only waving hello in 1986 and 1989 with the respective fly-bys of the Voyager 2 spacecraft.
The biggest difficulty in exploring these planets is that they are so far away that to reach them takes a spacecraft travelling at massive speeds – so fast that by the time they get there you need a massive amount of energy to kick them into orbit. With current technology missions to the outer fringes of the solar system, like New Horizons, are likely only to be fly-bys.
So, contrary to what you might think from recent media coverage, there really is so much more planetary exploration going on than that focused on Mars. To undertake these feats we’ve had to overcome technological hurdles and travelled massive distances at outrageous speeds.
I, for one, very much hope that we can continue to explore our solar system, Mars and beyond, at the same – or even faster – rate.
NASA’s hobbled Kepler space telescope may be able to detect alien planets again, thanks to some creative troubleshooting.
Kepler’s original planet hunt ended this past May when the second of its four orientation-maintaining reaction wheels failed, robbing the spacecraft of its ultraprecise pointing ability. But mission team members may have found a way to restore much of this lost capacity, suggesting that a proposed new mission called K2 could be doable for Kepler.
Engineers with the Kepler mission and Ball Aerospace, which built the telescope, have oriented the spacecraft such that it’s nearly parallel to its path around the sun. In this position, the pressure exerted by sunlight is spread evenly across Kepler’s surfaces, minimizing drift. [Gallery: A World of Kepler Planets]
This strategy is returning some promising results, mission officials say. During a 30-minute pointing test in late October, for example, Kepler captured an image of a distant star field that was within 5 percent of the image quality achieved during Kepler’s original mission.
“This ‘second light’ image provides a successful first step in a process that may yet result in new observations and continued discoveries from the Kepler space telescope,” Charlie Sobeck, Kepler deputy project manager at NASA’s Ames Research Center in Moffett Field, Calif., said in a statement.
The Kepler team is currently conducting tests to see if the spacecraft can maintain such pointing stability over periods of days and weeks — a necessity for discovering exoplanets.
Kepler launched in March 2009 on a mission to determine how frequently Earth-like planets occur around the Milky Way galaxy. The spacecraft finds exoplanets via the “transit method,” noting the telltale brightness dips caused when an alien world crosses the face of, or transits, its host star from the instrument’s perspective.
Kepler has been remarkably successful, spotting more than 3,500 planet candidates to date. Just 167 of them have been confirmed so far by follow-up observations, but mission scientists think 90 percent or so will end up being the real deal.
Researchers are still sifting through the mountains of data Kepler returned during its four years of science operations. Kepler team members have expressed confidence that they’ll find Earth analogs in these databases, allowing the mission’s primary goal to be achieved.
The proposed K2 mission would continue Kepler’s exoplanet hunt, albeit in a modified fashion. K2 would also gather data about supernova explosions, star formation and solar-system bodies such as asteroids and comets, among other things, team members have said.
The Kepler team has officially presented the K2 mission concept to NASA Headquarters, which is expected to decide by the end of the year if the idea progresses to a vetting stage called “senior review.” The ultimate fate of K2, and the Kepler spacecraft, will likely be known by the middle of next year, Kepler officials have said.
A mysterious blast of light spotted earlier this year near the constellation Leo was actually the brightest gamma-ray burst ever recorded, and was triggered by an extremely powerful stellar explosion, new research reports.
On April 27, several satellites — including NASA’s Swift satellite and Fermi Gamma-ray Space Telescope — observed an unusually bright burst of gamma radiation. The explosion unleashed an energetic jet of particles that traveled at nearly the speed of light, researchers said.
“We suddenly saw a gamma-ray burst that was extremely bright — a monster gamma-ray burst,” study co-author Daniele Malesani, an astrophysicist at the Niels Bohr Institute at the University of Copenhagen in Denmark, said in a statement. “This [was] one of the most powerful gamma-ray bursts we have ever observed with the Swift satellite.” [Top 10 Strangest Things in Space]
The gamma-ray burst was described in a series of studies published online today (Nov. 21) in the journal Science.
Gamma-ray bursts, or GRBs, are the most powerful type of explosions in the universe and typically mark the destruction of a massive star. The original stars are too faint to be seen, but the supernova explosions that signal a star’s death throes can cause violent bursts of gamma radiation, researchers said.
Gamma-ray bursts are usually short but extremely bright. Still, ground-based telescopes have a tough time observing them because Earth’s atmosphere absorbs the gamma radiation.
The extremely bright gamma-ray burst seen earlier this year, officially dubbed GRB 130472A, occurred in a galaxy 3.6 billion light-years away from Earth, which, though still far away, is less than half the distance at which gamma-ray bursts have previously been seen. This closer proximity to Earth enabled astronomers to confirm for the first time that one object can simultaneously create a powerful GRB and a supernova explosion.
“We normally detect GRBs at great distance, meaning they usually appear quite faint,” study co-author Paul O’Brien, an astronomer at the University of Leicester in the United Kingdom, said in a statement. “In this case, the burst happened only a quarter of the way across the universe — meaning it was very bright. On this occasion, a powerful supernova was also produced — something we have not recorded before alongside a powerful GRB — and we will now be seeking to understand this occurrence.”
The jet produced by the gamma-ray burst was formed when a massive star collapsed on itself and created a black hole at its center. This generated a blast wave that caused the stellar remnants to expand, producing a glowing shell of debris that was observed as an extremely bright supernova explosion.
After analyzing properties of the light produced by the gamma-ray burst, scientists determined that the original star was only three to four times the size of the sun, but was 20 to 30 times more massive. This extremely compact star was also rapidly rotating, the researchers said.
The GRB was the brightest and most energetic ever witnessed and triggered dynamic internal and external shock waves that are still not well understood. Though scientists have a clearer view of the violent explosion, mysteries remain. For instance, space telescopes detected more photons and more high-energy gamma-rays than theoretical models predicted for a gamma-ray burst of this magnitude.
Researchers are still investigating why the energy levels seen with GRB 130472A do not quite match predictions from existing models of gamma-ray bursts. Their results could lead to more refined theories about how particles are accelerated, which could help astronomers better predict the behavior of cosmic events.
“The really cool thing about this GRB is that because the exploding matter was traveling at [nearly] the speed of light, we were able to observe relativistic shocks,” study co-author Giacomo Vianello, a postdoctoral scholar at Stanford University in California, said in a statement. “We cannot make a relativistic shock in the lab, so we really don’t know what happens in it, and this is one of the main unknown assumptions in the model. These observations challenge the models and can lead us to a better understanding of physics.”
NASA’s prolific Kepler spacecraft could get a new mission that allows it to continue searching for alien planets, albeit in a modified fashion.
Kepler team members are drawing up plans to repurpose the space telescope, whose original exoplanet hunt was derailed in May, when the second of its four orientation-maintaining reaction wheels failed. The potential “K2″ mission would peer in the plane of Earth’s orbit, hunting primarily for planets circling relatively small stars.
“We expect to find dozens, or maybe even hundreds, of such planets,” Kepler principal investigator Bill Borucki, of NASA’s Ames Research Center, said here Monday (Nov. 4) at a news conference at Ames. [Gallery: A World of Kepler Planets]
“If we’re looking at smaller stars at shorter [orbital] periods, we may find, in fact, many of those are also in the habitable zone,” he added, referring to that just-right range of distances from a star where liquid water could potentially exist on a planet’s surface.
The Search For Another Earth | Video
Revolutionizing exoplanet science
Kepler launched in March 2009 on a mission to determine how frequently Earth-like planets occur around the Milky Way galaxy. The spacecraft detects alien worlds by noting the brightness dips caused when planets transit, or pass in front of, their host stars from the instrument’s perspective.
This week, scientists are discussing the mission’s latest alien planet discoveries at the Kepler Science Conference at NASA Research Park in Moffett Field, Calif.
The $600 million Kepler mission has been incredibly successful, spotting more than 3,500 potential exoplanets so far. Just 167 of them have been confirmed by follow-up observations to date, but scientists expect that 90 percent or so will end up being the real deal.
But Kepler is in a period of transition. The data-gathering portion of its primary mission ended in May when the second reaction wheel failed, robbing the spacecraft of its ultra-precise pointing ability. Engineers could not recover either wheel, and the mission team has thus been thinking hard about new ways to use Kepler, which is otherwise in good health.
“The spacecraft’s in great shape; the instrument’s in great shape,” Kepler project manager Charlie Sobeck, also of NASA’s Ames Research Center, said during a presentation here Monday at the second Kepler Science Conference. Kepler has plenty of fuel left as well, he added.
In August, NASA issued a call for new mission proposals, asking scientists around the world for ideas about the best ways to use a compromised Kepler. After reviewing these submissions, mission researchers have settled on K2, which they say should return valuable data in a variety of fields.
A new mission
During its original mission, Kepler stared continuously at more than 150,000 stars in a small patch of sky. But if K2 comes to pass, the instrument will take a broader view, covering five to 10 times more area.
The K2 mission would have Kepler study four to six “fields” per year, observing each one for a minimum of 40 days but preferably for 70 to 80 days, Kepler project scientist Steve Howell, also of Ames, said here Monday during his talk at the conference. The spacecraft would study 10,000 to 20,000 targets within each field, he added.
All of these fields would be roughly in the plane of Earth’s orbit — also known as the ecliptic — because such an orientation would maximize Kepler’s compromised pointing ability. (K2 is shooting for a photometric precision of less than 300 parts per million, compared to the original mission’s 20 or so parts per million, Howell said.)
The K2 mission would likely turn up many small exoplanets around small stars, including some in the habitable zone, Howell said. It could also spot a number of alien worlds around bright stars, which would make good targets for follow-up observation by NASA’s James Webb Space Telescope, an $8.8 billion instrument due to launch in 2018.
But K2 wouldn’t just be about exoplanets, Howell added. Kepler could also gather data about supernova explosions, star formation and solar-system bodies such as asteroids and comets, among other things. [Supernova Photos: Great Images of Star Explosions]
K2 would be conducted at the same time that researchers are performing “close-out” work for the original Kepler mission, making sure they have squeezed all the important information out of the instrument’s enormous data set. Both activities would likely be undertaken without a bump in Kepler’s budget, which is currently about $18 million per year, Sobeck said.
“Clearly, this is a challenge,” he said. “It’s not beyond the reach. I think it’s something that we might be able to achieve.”
The Kepler team is currently working on the close-out plan for Kepler’s original mission and the official proposal for K2, both of which are due to NASA headquarters by Nov. 20, Howell said.
NASA officials will then decide by Dec. 6 if the K2 idea will progress to a vetting stage called “senior review,” he added. But the ultimate call on K2, and Kepler’s fate, likely won’t come for a while.
“We expect to hear that decision sometime toward the middle of next year,” Borucki said.
Three NASA space telescopes are teaming up to give astronomers their best-ever looks at some of the most distant objects in the universe.
The space agency’s Hubble, Spitzer and Chandra space telescopes will collectively observe six huge galaxy clusters over the next three years as part of a project called The Frontier Fields. Working together, the trio should be able to spot galaxies that existed just a few hundred million years after the Big Bang created our universe 13.8 billion years ago, NASA officials said.
“The Frontier Fields program is exactly what NASA’s Great Observatories were designed to do: working together to unravel the mysteries of the universe,” NASA science chief John Grunsfeld said in a statement. “Each observatory collects images using different wavelengths of light, with the result that we get a much deeper understanding of the underlying physics of these celestial objects.” [Cosmic View! Latest Hubble Space Telescope Photos]
The Hubble Space Telescope observes in visible, near-infrared and near-ultraviolet wavelengths. Spitzer is optimized to view in the infrared, while Chandra sees best in X-ray light.
The Frontier Fields project will take advantage of a phenomenon called gravitational lensing, in which the gravitational field of a massive foreground object bends and brightens the light from a more distant object, acting like a lens.
In this case, the six huge galaxy clusters — starting with Abell 2744, which is also known as Pandora’s Cluster — will be the lenses, and the magnified objects will be extremely dim and far-flung galaxies, some of which have likely never been observed before, researchers said.
“The idea is to use nature’s natural telescopes in combination with the great observatories to look much deeper than before and find the most distant and faint galaxies we can possibly see,” Jennifer Lotz, a principal investigator with the Space Telescope Science Institute in Baltimore, said in a statement.
Data from Hubble and Spitzer will help astronomers measure these galaxies’ distances and masses accurately, researchers said. Chandra’s observations, meanwhile, will help astronomers determine the galaxy clusters’ masses and gravitational lensing power, as well as spot background galaxies harboring supermassive black holes at their cores.
“We want to understand when and how the first stars and galaxies formed in the universe, and each great observatory gives us a different piece of the puzzle,” said Peter Capak, Spitzer principal investigator for the Frontier Fields program at NASA’s Spitzer Science Center at the California Institute of Technology in Pasadena.
Scientists have been using data collected by NASA’s now-defunct Kepler space telescope not only to look for planets beyond the solar system but also to probe their parent stars, which pulsate as they spin, causing variations in brightness.
The Kepler observatorycan detect these oscillations, much like it detected dips in target stars’ light due to planets passing by, or transiting, relative to the telescope’s line of sight.
Working both types of observations, scientists have now found the first multi-planet system that is tilted out of alignment with the host star.
“When we found this system, it was a major surprise. They didn’t form this way,” astronomer Daniel Huber, with NASA’s Ames Research Center in Moffett Field, Calif., told Discovery News. [The Strangest Alien Planets (Gallery)]
The star, known as Kepler-56, is about 45 degrees out of alignment from the orbital plane of a pair of planets, which circle their parent star in 10- and 20 days respectively. Trying to determine what elbowed the planets out from the equatorial plane of their star led Huber and colleagues to a third, non-transiting, massive companion, which could be another planet or a star.
“We think it’s responsible for causing this misalignment,” Huber said.
The third, outer companion is inclined to the orbital plane of the inner planets. Scientists suspect its torque is tilting the orbital plane of the inner planets, with respect to the equatorial plane of the parent star.
Follow-up ground observations are underway to figure out the third body’s orbit and size, information scientists need to determine whether it is a planet, a brown dwarf star or another type of star.
“That is still a bit of an open question, but for the general conclusion of the theory of how this system formed it doesn’t really matter whether it’s a star or a planet. It just matters that you have a more massive companion in this outer orbit which can tilt the inner ones, which are much less massive,” Huber said.
The research has implications for understanding how planetary systemsform and evolve. It also may help solve a long-standing mystery about how some giant planets settled into orbits far closer to their host stars than Mercury orbits the sun.
These so-called hot-Jupiters were the first planets discovered beyond the solar system.
“Some kind of dynamically disruption must have happened a long time ago that caused a planet to migrate so close to its host star,” Huber said.
The new research shows orbital upheavals are not just limited to hot-Jupiter systems.
“Such a dynamical tilting scenario had been recently suggested theoretically, and has now been observed for the first time,” astronomer Andrea Miglio, with the University of Birmingham in England, wrote in an email to Discovery News.
Meanwhile, scientists are continuing to mine the Kepler data for evidence of other misaligned systems.
Earth and the rest of the solar system coalesced from a giant cloud of gas and dust more than 4.5 billion years ago. Many of the details about the galactic neighborhood in which the solar system arose still remain a mystery.
Meteorites contain some of the oldest material in the solar system, dating back to its formation. As such, researchers often analyze these objects in order to discover what materials were present when the sun, Earth and other planets were born. This study sheds light on where these solar system bodies might have come from.
All elements heavier than nickel are ultimately created by supernovas, giant explosions resulting from the deaths of stars. These explosions are bright enough to momentarily outshine their entire galaxies. Now, scientists analyzing meteorites have found that a supernova may have injected matter into the solar system within a small window of time after the solar system’s first solids formed.
“This is evidence for supernova addition at the very start of our solar system, over 4.5 billion years ago,” said the meteorite study’s lead author,Gregory Brennecka, a cosmochemist at Lawrence Livermore National Laboratory.
Brennecka and his colleagues investigated the Allende meteorite, which fell to Earth as a fireball in Mexico in 1969. Theyfocused on lumps within this meteorite known as calcium-aluminum-rich inclusions. These particles are some of the oldest objects in the solar system — they were the first solids to form in the protoplanetary disk that eventually gave rise to Earth and the other planets.
The scientists focused on a wide range of isotopes within the inclusions. In general, elements come in a variety of isotopes that differ in how many neutrons they possess in their atomic nuclei; carbon-12 has six neutrons, while carbon-13 has seven. (Both have six protons.)
Brennecka and his colleagues discovered these inclusions all had similar concentrations of isotopes. However, the concentrations were distinct from the average composition of the materials that make up the bulk of meteorites and the Earth.
The researchers propose the inclusions formed close to the young sun, possibly within a span as short as 20,000 to 50,000 years. As such, matter from a nearby supernova did not pollute these inclusions, as it did the outer regions of the protoplanetary disk. The inclusions later mixed with the material that went on to make the Allende meteorite and other rocks.
“Not only do we know that the supernova happened, we can see what material was injected and how it changed the elemental and isotopic composition of our solar system,” Brennecka told SPACE.com.
These findings are consistent with the notion that the solar system developed in an active star-forming region of the galaxy. Stellar nurseries are often home to stars that go supernova.
Future research can aim to better understand the fingerprints of this supernova in other samples “and how much influence it and possible other supernovae had on the development of our solar system,” Brennecka said.
Brennecka and his colleagues Lars Borg and Meenakshi Wadhwa detailed their findings online Oct. 7 in the journal Proceedings of the National Academy of Sciences.
Astronomers using NASA’s flagship space telescopes have spotted what appears to be densest nearby galaxy ever seen, with stars packed so tightly that they are likely 25 times closer to each other than the stars in our own Milky Way galaxy.
The super-crowded galaxy is called M60-UCD1 and is located about 54 million light-years away from Earth and the sun. It weighs a whopping 200 million times more than the sun, packing half of this mass within 80 light-years of its center, scientists said. Such crowded conditions make M60-UCD1 a type of ultra-compact dwarf galaxy.
Scientists discovered the galaxy using NASA’s Hubble Space Telescope, making follow-up observations using the space agency’s Chandra X-ray Observatory and ground-based optical telescopes, such as the Keck Observatory in Hawaii.
Inside the galaxy’s heart is a bright source of X-rays that came to light in images from the Chandra X-Ray Observatory. The X-rays may be coming from a giant black hole that’s about 10 million times the mass of the sun, astronomers say. And if the X-rays are indeed coming from such a massive black hole, it would mean M60-UCD1 is likely left over from a galaxy that was 50 to 200 times larger.
“Large black holes are not found in star clusters, so if the X-ray source is in fact due to a massive black hole, it was likely produced by collisions between the galaxy and one or more nearby galaxies,” a NASA statement read. “The mass of the galaxy and the sun-like abundances of elements also favor the idea that the galaxy is the remnant of a much larger galaxy.”
M60-UCD1′s growth would have been stunted for billions of years after the collision, astronomers added. In fact, they estimate the dense galaxy has been around for more than 10 billion years.
Just two decades after discovering the first world beyond our solar system, astronomers are closing in on alien planet No. 1,000.
Four of the five main databases that catalog the discoveries of exoplanets now list more than 900 confirmed alien worlds, and two of them peg the tally at 986 as of today (Sept. 26). So the 1,000th exoplanet may be announced in a matter of days or weeks, depending on which list you prefer.
That’s a lot of progress since 1992, when researchers detected two planets orbiting a rotating neutron star, or pulsar, about 1,000 light-years from Earth. Confirmation of the first alien world circling a “normal” star like our sun did not come until 1995
And the discoveries will keep pouring in, as astronomers continue to hone their techniques and sift through the data returned by instruments on the ground and in space.
The biggest numbers in the near future should come from NASA’s Kepler space telescope, which racked up many finds before being hobbled in May of this year when the second of its four orientation-maintaining reaction wheels failed.
Kepler has identified 3,588 planet candidates to date. Just 151 of these worlds have been confirmed so far, but mission scientists have said they expect at least 90 percent will end up being the real deal.
But even these numbers, as impressive as they are, represent just the tip of our Milky Way galaxy’s immense planetary iceberg. Kepler studied a tiny patch of sky, after all, and it only spotted planets that happened to cross their stars’ faces from the instrument’s perspective.
Many more planets are thus out there, zipping undetected around their parent stars. Indeed, a team of researchers estimated last year that every Milky Way star hosts, on average, 1.6 worlds — meaning that our galaxy perhaps harbors 160 billion planets.
And those are just the worlds with obvious parent stars. In 2011, a different research team calculated that “rogue planets” (which cruise through space unbound to a star) may outnumber “normal” exoplanets by 50 percent or so.
Nailing down the numbers is of obvious interest, but what astronomers really want is a better understanding of the nature and diversity of alien worlds.
And it’s becoming more and more apparent that this diversity is stunning. Scientists have found exoplanets as light and airy as Styrofoam, for example, and others as dense as iron. They’ve also discovered a number of worlds that appear to orbit in their stars’ habitable zone — that just-right range of distances that could support the existence of liquid water and thus, perhaps, life as we know it.
But the search continues for possibly the biggest exoplanet prize: the first true alien Earth. Kepler was designed to determine how frequently Earth-like exoplanets occur throughout the Milky Way, and mission scientists have expressed confidence that they can still achieve that primay goal. So some Earth analogs likely lurk in Kepler’s data, just waiting to be pulled out.
The five chief exoplanet-discovery databases, and their current tallies, are: the Extrasolar Planets Encyclopedia (986); the Exoplanets Catalog, run by the University of Puerto Rico at Arecibo’s Planetary Habitability Laboratory (986); the NASA Exoplanet Archive (905); the Exoplanet Orbit Database (732); and the Open Exoplanet Catalog (948).
The Planetary Habitability Lab keeps track of all five databases, whose different numbers highlight the uncertainties involved in exoplanet detection and confirmation.
The explosive collisions of icy comets with planets and moons generated the vital building blocks of life, spreading these necessary ingredients throughout the solar system, researchers say.
“The important implication is that the complex precursors to life are widespread, thus increasing the chances of life evolving elsewhere,” study co-author Mark Price, a space scientist at the University of Kent in England, told SPACE.com.
Comets are known to possess organic compounds. Scientists have long suggested that comets helped bring the ingredients of life to the early Earth. [7 Theories on the Origin of Life]
Astronomers have detected ammonia and other compounds in comets such as Halley’s Comet that are the precursors of amino acids, the basic components of proteins. Indeed, the simplest amino acid, glycine, was recently discovered in samples of the Comet 81P/Wild-2 collected by NASA’s Stardust spacecraft.
However, more complex amino acids are needed for life. Computer models from physical chemist Nir Goldman at the Lawrence Livermore National Laboratory in California suggested impacts could form complex amino acids, and Price and his colleagues set out to replicate these simulations, while astrobiologist Zita Martins at Imperial College in London and her colleagues helped look for any resultant amino acids.
“Impacts are ubiquitous in the solar system — we see impact craters on every solid surface in the solar system,” Price said. “Due to gravity, we know these impacts must occur at very high velocities, kilometers per second. During such impacts, pressures and temperatures get very high, providing an environment that can induce chemical changes in target and projectile materials. One such change is that simple molecules can become more complicated ones.”
In experiments, the researchers fired steel projectiles at speeds of up to 16,000 mph (25,200 km/h) at ice mixtures similar to ones found in comets. The targets could be difficult to work with — “a mix of carbon dioxide ice, ammonia and methanol gets extremely cold, minus 80 degrees Celsius (minus 112 degrees Fahrenheit), and handling the ices and containers meant using several layers of clean gloves, face masks and coveralls,” Price said. “Even so, this still resulted in frostbitten fingers!”
The results included several amino acids, including L-alanine, an important component of proteins on Earth. Martins, Price, Goldman and their colleagues detailed their findings online Sunday (Sept. 15) in the journal Nature Geoscience.
Price cautioned, “We have not created life. Not even close. What we have done is demonstrate a process that takes molecules that were present at the time of the birth of the solar system and made them into molecules that are required for life. It’s like taking simple LEGO bricks and sticking two together. You are a long way from building a house, but it is a start.”
The researchers suggest that icy impacts — whether from icy comets against rocky planets or rocky or icy bodies against icy surfaces such as the moons of Jupiter and Saturn — could have manufactured complex organic molecules.
“As impacts occur everywhere we look, this implies that complicated molecules are also widespread throughout the solar system,” Price said. “We have managed to generate a result that may increase the chance of life being present in an environment outside of the Earth, such as under the ice of Enceladus or Europa.”
Future research can analyze what other compounds might form during such impacts — for instance, whether complex molecules can be altered into even more complex molecules.
The dwarf planet Ceres, which orbits the sun in the asteroid belt between Mars and Jupiter, is a unique body in the solar system, bearing many similarities to Jupiter’s moon Europaand Saturn’s moon Enceladus, both considered to be potential sources for harboring life.
“I think of Ceres actually as a game changer in the solar system,” Schmidt said.
“Ceres is arguably the only one of its kind.”
The innermost icy body
When Ceres was discovered in 1801, astronomers first classified it as a planet. The massive body traveled between Mars and Jupiter, where scientists had mathematically predicted a planet should lie. Further observations revealed that a number of small bodies littered the region, and Ceres was downgraded to just another asteroid within the asteroid belt. It wasn’t until Pluto was classified as a dwarf planetin 2006 that Ceres was upgraded to the same level.
Ceres is the most massive body in the asteroid belt, and larger than some of the icy moons scientists consider ideal for hosting life. It is twice the size of Enceladus, Saturn’s geyser-spouting moon that may hide liquid water beneath its surface.
Unlike other asteroids, the Texas-sized Cereshas a perfectly rounded shape that hints toward its origins.
“The fact that Ceres is so round tells us that it almost certainly had to form in the early solar system,” Schmidt said. She explained that a later formation would have created a less rounded shape.
The shape of the dwarf planet, combined with its size and total mass, reveal a body of incredibly low density.
“Underneath this dusty, dirty, clay-type surface, we think that Ceres might be icy,” Schmidt said. “It could potentially have had an ocean at one point in its history.”
“The difference between Ceres and other icy bodies [in the solar system] is that it’s the closest to the sun,” Castillo-Rogez said.
Less than three times as far as Earth from the sun, Ceres is close enough to feel the warmth of the star, allowing ice to melt and reform.
Investigating the interior of the dwarf planet could provide insight into the early solar system, especially locations where water and other volatiles might have existed.
“Ceres is like the gatekeeper to the history of water in the middle solar system,” Schmidt said.
Studying the surface
As large as Ceres is, its distance has made it a challenge to study from Earth. Images taken by the space-based Hubble Space Telescope provided some insight to its surface, but to be sighted, features could be no larger than 25 kilometers (15.5 miles) in diameter.
Several round circular spots mar the terrain, features which Schmidt said could be any one of a number of geologic terrains, including potentially impact basins or chaos terrains similar to those found on Europa. The largest of these, named Piazzi in honor of the dwarf planet’s discoverer, has a diameter of about 250 km (155 miles). If this feature is an impact basin, it would have been formed by an object approximately 25 km (15.5 miles) in size.
But for Schmidt, this is another possible indication about the dwarf planet’s surface.
“It doesn’t mean that Ceres hasn’t been hit by something bigger than 25 kilometers,” she said. “It just means that whatever is going on on Ceres has totally erased [the topographic signature of that event].”
Ceres may have suffered major impacts, especially during periods of heavy bombardment early in the solar system’s history. If the surface contained ice, however, those features may have been erased.
Telescopes on Earth have also been able to study the light reflecting from the planet and read its spectra.
“The spectrum is telling you that water has been involved in the creation of materials on the surface,” Schmidt said.
The spectrum indicates that water is bound up in the material on the surface of Ceres, forming a clay. Schmidt compared it to the recent talk of mineralsfound by NASA’s Curiosityon the surface of Mars. [The Search for Life on Mars (A Photo Timeline)]
“[Water is] literally bathing the surface of Ceres,” she said.
In addition, astronomers have found evidence of carbonates, minerals that form in a process involving water and heat. Carbonates are often produced by living processes.
The original material formed with Ceres has mixed with impacting material over the last 4.5 billion years, creating what Schmidt calls “this mixture of water-rich materials that we find on habitable planets like the Earth and potentially habitable planets like Mars.”
A prime site for life?
Water is considered a necessary ingredient for the evolution of life as we know it. Planets that may have once contained water, such as Mars, as well as moons that could contain it today, like Enceladus and Europa, are all thought to be ideal for hosting or having once hosted life.
Because of its size and closeness, Schmidt calls Ceres “arguably more interesting than some of these icy satellites.”
“If it’s icy, it had to have an ocean at some point in time,” she said.
Castillo-Rogez compared Earth, Europa, and Ceres, and found that the dwarf planet bore many similarities to Earth, perhaps more than Jupiter’s icy moon. Both Earth and Ceres use the Sun as a key heat source, while Europa takes its heat from its tidal interaction with Jupiter. In addition, the surface temperature of the dwarf planet averages 130 to 200 degrees Kelvin, compared to Earth’s 300 K, while Europa is a frosty 50 to 110 K.
“At least at the equator where the surface is warmer, Ceres could have preserved a liquid of sorts,” Castillo-Rogez said.
Liquid water could exist at other points on the dwarf planet known as cold traps, shadowed areas where frozen water could remain on the surface. Such icy puddles have been found on Earth’s moon. [Photos: Europa, Mysterious, Icy Moon of Jupiter]
“The chemistry, thermal activity, the heat source, and the prospect for convection within the ice shell are the key ones that make us think that Ceres could have been habitableat least at some point in its history,” Castillo-Rogez said.
The future of Ceres
As scientists develop more information about Europa and Enceladus, there has been a greater call to investigate the two prime sites for life. But Schmidt and Castillo-Rogez think that Ceres could also be a great boon for astrobiology and space exploration.
“It’s not a difficult environment to investigate,” she said. “As we think about the future of landed missions for people and rovers, why not go to Ceres?”
Though it would be more challenging to drill into than Europa, which boasts an icy surface layer, the dwarf planet would make a great site to rove around on. Schmidt also noted that it could make a great launching point when it comes to reaching the outer solar system. Its smaller mass would make it easier to land on — and leave — than Mars, which could make it a good site for manned missions.
“We have such a big planet bias, we have such a bias for things that look exactly like us,” Schmidt said.
“In this kind of special place in the solar system, we have a very unique object that might be telling us a lot about what we don’t know about building a habitable planet.”
NASA’s Dawn mission launched September 27, 2007. It traveled to the asteroid Vesta, where it remained in orbit from July 2011 to July 2012 before heading to Ceres. It is slated to spend five months studying the dwarf planet, though Schmidt expressed hope that the craft would continue working beyond the nominal mission, allowing the team to study the icy body even longer.
Castillo-Rogez pointed out that not only will Dawn reach Ceres in 2015, the European Space Agency’s Rosetta spacecraft will be escorting the comet Churyumov-Gerasimenko around the sun that year, while NASA’s New Horizons mission will be reaching Pluto and its moon Charon.
“’15 is going to be a great year for icy bodies,” Castillo-Rogez said.
“I think when we get to Ceres, it’s just going to be an absolute game changer, a new window into the solar system that we wouldn’t have without going there,” Schmidt said.
The revolutionary planet-hunting activities of NASA’s prolific Kepler space telescope have come to an end.
NASA has given up hope of restoring the Kepler spacecraft to full health and is now attempting to determine what the observatory can accomplish in its compromised state, agency officials announced on August 15th.
“We are now moving on to the next phase of Kepler’s mission, because that’s what the data requires us to do,” Paul Hertz, director of NASA’s astrophysics division, told reporters during a press conference today. “This is not the last you’ll hear from Kepler. There’s a huge amount of data collected that we’ll continue to analyze.” [Gallery: A World of Kepler Planets]
The $600 million Kepler mission launched in March 2009 on a 3.5-year prime mission to determine how commonly Earth-like planets occur around the Milky Way galaxy.
Kepler detects exoplanets by noting the tiny brightness dips caused when these worlds cross in front of, or transit, their parent stars. The observatory needs three working reaction wheels — gyroscope-like devices that maintain Kepler’s position in space — to do this precision work.
Kepler had four of these wheels when it launched — three for immediate use and one spare. But one wheel, known as number 2, failed in July 2012. And then wheel four conked out on May 11 of this year, halting the spacecraft’s planet hunt.
Mission engineers have since managed to get those two malfunctioning wheels spinning again, but both of them still exhibit too much friction to support Kepler’s fine-pointing work. So the observatory’s original mission is over, officials said today.
“We do not believe that we can recover three-wheel operations, or Kepler’s original science mission,” Hertz said.
Sending astronauts out to fix Kepler, as was done five times with NASA’s Hubble Space Telescope, is not an option. That’s because Kepler orbits the sun rather than Earth and is currently millions of miles from our planet.
The focus has now shifted to examining what Kepler can accomplish with just two healthy wheels and its thrusters, Hertz added.
To that end, NASA is conducting two separate studies: an engineering assessment to see what the spacecraft is capable of, and a science study to determine if a modified mission is worth funding. (It currently costs about $18 million per year to operate the telescope.)
Both studies are due in the fall, Hertz said.
“NASA may use a senior review to help us prioritize a two-wheel Kepler mission against the continued operation of other NASA astrophysics missions,” he said. “Only after weighing these considerations will NASA be in a position to make a decision on the future of Kepler operations.”
There are a variety of possible uses for Kepler in the future, mission scientists say. The observatory could scan the heavens for asteroids, comets and supernova explosions, for example. And it may still be able to detect huge alien planets using a technique called gravitational microlensing. (In this method, astronomers watch what happens when a massive object passes in front of a star; the closer object’s gravitational field bends and magnifies the star’s light, acting like a lens.)
But it’s still to soon to tell which, of any, of these missions will pan out.
“Until we have analyzed the full capability of the mission and we have looked at what the requirements are in terms of guidance, we really have no way no way of knowing which of these missions would be practical,” said Kepler principal investigator Bill Borucki, of NASA’s Ames Research Center in Moffett Field, Calif.
Lots of discoveries to come
Kepler has detected 3,548 candidate planets to date, 135 of which have been confirmed by follow-up observations. Mission scientists expect more than 90 percent of the observatory’s finds will end up being the real deal.
And there will be more discoveries to come, whatever Kepler ends up doing in the future. It will take several more years to pore through all of the observatory’s data, Borucki said.
“We expect hundreds, maybe thousands of new planet discoveries, including the long-awaited Earth-size planet orbiting a star as hot as our sun — so a very sun-like star,” he said.
Kepler outlasted its prime mission lifespan of 3.5 years, and it should be able to accomplish its main goal despite the reaction-wheel failures, Borucki added.
“In the next two years, when we complete this analysis, we’ll be able to answer the question that inspired the Kepler mission: Are Earths common or rare in our galaxy?” he said.
The small orbital period — one of the shortest ever discovered for an alien planet among the worlds discovered by NASA’s Kepler Space Telescope — means the planet is far outside what is considered the habitable zone of its star, where liquid water, and maybe life, could exist. In fact, scientists have described the new world as a so-called “lava planet.”
The find, however, excites astronomers because the host star of the planet, called Kepler-78b, is bright enough for other telescopes to spot the world. This is a relieving note for the research team given that the Kepler Space Telescope’s prime exoplanet mission officially ceased Thursday (Aug. 15), scientists said. The spacecraft had to cut its prime planet-hunting mission short when two of its orientation-controlling reaction wheels failed. [The Strangest Alien Planets (Gallery)]
“With a lot of effort and a lot of patience, you could detect the transit from the largest telescopes,” Roberto Sanchis-Ojeda, a Ph.D. student at the Massachusetts Institute of Technology who led the research, told SPACE.com. “We also think it’s possible with the Hubble Space Telescope. From space, you should not have any issue [spotting it.]”
A hot Earth
Kepler-78b is about 100 times closer to its star than the Earth is to the sun, and orbiting in a star system that is about 750 million years old — about six times younger than the solar system. The planet’s surface bakes at an iron-melting temperature somewhere between 3,680 degrees Fahrenheit (2,026 degrees Celsius) and 5,120 degrees Fahrenheit (2,826 degrees Celsius).
Among other planetary candidates found by Kepler, only a handful have periods less than half a day long. The shortest confirmed orbital period is 10.9 hours, which belongs to Kepler-42c, while the shortest unconfirmed one (held by a planet candidate called KOI 1843) is only 4.3 hours.
Sanchis-Ojeda’s team noted that many researchers are looking at longer-period planets that could be in habitable zones, which excites scientists because of the possibility of life existing on these worlds. But the researchers decided to plumb Kepler’s data to focus on tight orbital periods, to see if more of these planets exist and how many of them are out there.
“Hot Jupiters,” or Jupiter-size planets that are close to their stars, are the most common finds in this field because they are easy to detect. Spotting something the size of Earth, therefore, was a special moment for the team.
“It turned out to be a really rewarding session because we ended up finding this planet,” Sanchis-Ojeda said.
Because Kepler-78b transited, or crossed in front of, the face of its star, which is similar in size to Earth’s sun, the team was able to pinpoint its size at a little larger than one Earth radius.
And in a more unusual find, the scientists discovered the planet’s surface is so hot that it shines brightly in visible light, allowing the team to isolate the light of the planet from its star.
As Kepler-78b passed behind its star, light curve measurements allowed researchers to confirm that the planet is reflecting at least some of the light it receives from its star. How much light is unknown, and will require further observations to determine, Sanchis-Ojeda noted.
Follow-up observations could also determine the mass of the planet, which would give a sense of its composition. The team is almost certain that Kepler-78b is rocky, because most planets of that size are rocky, as opposed to gaseous.
A dazzling star explosion discovered in the night sky last week is the brightest nova seen from Earth in at least five years and its visible now to the naked eye.
The Nova Delphinus 2013 star explosion can be seen by the naked eye from places without too much light pollution, skywatching experts say. The stellar phenomenon is expected to be visible for weeks to come, and its location in the night sky should make the nova easy for even novice stargazers to spot.
“The nova is easy to locate north of the lovely star pattern of Delphinus. And the constellation Sagitta, the Arrow, points right toward it,” Tony Flanders, associate editor of Sky & Telescope, said in a statement. [See Stargazer Photos of Nova Delphinus 2013 (Gallery)]
Arne Henden, who is director of the American Association of Variable Star Observers (AAVSO), added that the nova will be easily visible in the eastern sky starting in the early evening.
“The nova can be seen with binoculars even from light-polluted metropolitan areas,” Henden said in a statement. “Hundreds of observers, many for the first time, have submitted brightness estimates of the nova to the AAVSO.”
In the last 112 years, 47 novas have brightened into naked-eye view and novas as bright as Nova Delphinus 2013 occur about every 10 years, skywatching experts say. The new nova has also been referred to as Nova Delphini 2013.
Nova Delphinus 2013 was discovered by Koichi Itagaki of Yamagata, Japan, in an image taken on Aug. 14. Itagaki noticed a bright spot that was not present in a photo of the sky that he took the previous day.
Before erupting, the nova was apparently a dull magnitude +17 star on the scale used by astronomers to measure the brightness of night sky objects, in which higher numbers denote dimmer objects. The threshold of what the human eye can see is about magnitude +6.5.
But Nova Delphinus 2013 increased in brightness by about 100,000 times when it reached a peak magnitude 4.5 on Aug. 16. Now the nova is holding steady at magnitude 4.9, but its intensity could change.
“It could remain at this brightness for many more days, it could re-brighten, or it could fade rapidly,” Henden explained.
A typical nova occurs in a binary system where one at least one star is a white dwarf, a tiny, super-dense core of a star. Its companion star sends a stream of hydrogen onto the white dwarf and when that gaseous layer grows thick and dense enough, a runaway hydrogen-fusion reaction is set off.
Unlike in supernovas, white dwarfs survive novas, and the process may repeat in a few years to tens of thousands of years.