Dr Jo Dunkley explores the latest research on the ‘missing’ 95% at Science Oxford Live at 7:30pm on Thursday the 25th of August.

One of the outstanding problems in cosmology is to understand the ‘missing’ 95% of the universe. The familiar atoms we are all made of only make up a small fraction of what we think is out there.

We think that about a quarter of the universe is made of Dark Matter, most likely an undiscovered type of particle that we cannot see, but feels the effect of gravity.

The other 70% is what we call Dark Energy, thought to be a form of energy that has the strange effect of making the expansion of the universe accelerate.

Dr. Jo Dunkley is a lecturer at the University of Oxford and is involved in determining properties of the universe including the nature of Dark Matter and Dark Energy.

Finding out what these are, and coming up with ways to investigate their behaviour, is a central part of current research in cosmology. It brings together research in astrophysics and particle physics, and combines theoretical studies with large international experiments.

Dominic McDonald, Head of Public Engagement at Science Oxford Live, said “I first met Jo in 2006 when she was the keynote speaker for a conference to inspire 13-16 year olds. Six years on she is now a leading figure on the Dark Universe and I am delighted to welcome her to Science Oxford Live.”

Asked about the subject of Thursday’s event, Dominic added
“this is a huge unsolved area. We do not know what the vast majority of the universe is actually made up of. Oxford University is leading research into this and it will be fascinating to hear about this challenging area, including the latest developments, from Jo.”

Emma Wightman, Programmes Delivery Manager at Science Oxford Live, said
“Jo is an exceptional Cosmologist and Astrophysicist and a fantastic role model.”

Join Dr. Jo Dunkley at Science Oxford Live on Thursday 25th August to hear about the latest research into the ‘Missing’ universe.

Book your place now

More about Dr. Jo Dunkley

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Press Release

How Do Scientists Compute Probabilities for Near-Earth Object Collisions with Earth?

OK, there will probably not be an Apocalypse, but scientists did discover an asteroid that has a 1 in 1000 chance of hitting Earth in 2182. It’s really far away and a pretty low probability, so why should anyone
care? Well, it’s not quite like 1 in 1000 chance that someone will lose 100 bucks in a stupid bet or a 1 in 1000 chance that it rains on someone’s wedding day. This is a 1 in 1000 chance that millions, billions (or trillions by that point?) of humans beings and countless other species may be vaporized. That’s why. 172 years is not exactly a long time on the scale of the universe either.

How do scientists come up with this probability? They could just be making it up and no one would know the difference…but they’re not. They use a technique called Monte Carlo simulation. They make a mathematical model of the situation at hand – in this case, an asteroid and the Earth in orbit around the Sun. The orbit of the Earth is very well-known, but the orbit of the asteroid is not known as well and may even change a bit. Many simulations – or trials – are run, each with slightly different conditions. The different conditions may be, for example, slight variations on current position, size, speed and rotation of the asteroid based on what is already known about it from measurements. The number of simulations run must make it so that the determined probability of the event in question – in this case, the asteroid hitting Earth – is statistically significant.

Statistical Significance and Rare Events

As an example of what statistically significant means, imagine flipping a coin. Each flip is a simulation. If the coin is flipped twice, it may land head-head by chance. One could say from the two simulations that a coin has a 100% probability of landing heads up, but this is incorrect. It happened by chance that there were two heads. If the two-flip experiment were run again, the experiment would probably not yield the same results.

Many simulations have to be run so that nothing is left to chance. If the coin were flipped 100 times, there would probably be close to 50 heads…if it were flipped 1000 times, it would probably be even closer to
500 heads, meaning that the probability of getting heads is approaching 50%. An experiment of 100 coin flips gives a statistically significant estimate, where two flips does not. The two-flip experiment would change a lot between different experiments, but the 100-flip experiment would not change that much between experiments. This is the crux of statistical significance.

The number of simulations required depends inversely on how likely the event is. If the event is rare, like an asteroid hitting Earth, 1000 simulations may be run, all of them without the event occurring. This doesn’t mean that the event will never occur. It is just likely that it doesn’t occur in the first 1000 simulations, so many, many more simulations need to occur.

As more and more simulations are run, it is less and less likely that something happened by chance and a more accurate probability can be determined. Possibly millions of simulations are needed to determine the probability of such a rare event with any statistical significance. The lack of respect for statistical significance leads to a lot of bad science.

Why this asteroid is significant (in the non-statistical context)

This isn’t the first asteroid discovered that may collide with Earth someday, but this asteroid is special. It was determined that if this asteroid needed to be deflected to avoid hitting Earth, it would have to be deflected before 2080 because of the uncertainty in its path due to the Yarkovsky effect. The Yarkovsky effect changes the trajectory of the asteroid because it is radiating absorbed heat from the sun while rotating, which causes a force on the asteroid.

Discovering this asteroid suggests that the window for searching for Earth-bound asteroids should be extended beyond the current window of 100 years, because if this asteroid were not discovered until 2080, we would not be able to change its course with technology we have available today.

Moonbase Alpha is a NASA-funded multiplayer game scenario with 20 minutes of play set on a hypothetical lunar outpost in 3-D immersive setting. This is a proof of concept to show NASA content – lunar architecture in this case – and a cutting edge game engine could be combined to produce a fun game and inspire interest in STEM education.

About Moonbase Alpha Development
NASA released the game on Valve’s Steam network, and will use the Steamworks suite of services for server browsing, leaderboards, statistics and more. Steam has more than 25 million accounts and has released more than 1,100 games. It was built on Epic Games’ Unreal Engine 3. The Army Game Studio developed the game with primary development support from Virtual Heroes, a division of Applied Research Associates in Research Triangle Park, N.C. This collaboration between NASA and the Army’s Aviation Missile Research Development and Engineering Center is an example of government agencies working together to improve education in the STEM fields.

Article Credit: NASA http://www.nasa.gov/moonbasealpha/

Using a combination of instruments on ESO’s Very Large Telescope, astronomers have discovered the most massive stars to date, one weighing at birth more than 300 times the mass of the Sun, or twice as much as the currently accepted limit of 150 solar masses. The existence of these monsters — millions of times more luminous than the Sun, losing weight through very powerful winds — may provide an answer to the question “how massive can stars be?”

A team of astronomers led by Paul Crowther, Professor of Astrophysics at the University of Sheffield, has used ESO’s Very Large Telescope (VLT), as well as archival data from the NASA/ESA Hubble Space Telescope, to study two young clusters of stars, NGC 3603 and RMC 136a in detail. NGC 3603 is a cosmic factory where stars form frantically from the nebula’s extended clouds of gas and dust, located 22 000 light-years away from the Sun. RMC 136a (more often known as R136) is another cluster of young, massive and hot stars, which is located inside the Tarantula Nebula, in one of our neighbouring galaxies, the Large Magellanic Cloud, 165 000 light-years away.

The team found several stars with surface temperatures over 40 000 degrees, more than seven times hotter than our Sun, and a few tens of times larger and several million times brighter. Comparisons with models imply that several of these stars were born with masses in excess of 150 solar masses. The star R136a1, found in the R136 cluster, is the most massive star ever found, with a current mass of about 265 solar masses and with a birthweight of as much as 320 times that of the Sun.

In NGC 3603, the astronomers could also directly measure the masses of two stars that belong to a double star system, as a validation of the models used. The stars A1, B and C in this cluster have estimated masses at birth above or close to 150 solar masses.

Very massive stars produce very powerful outflows. “Unlike humans, these stars are born heavy and lose weight as they age,” says Paul Crowther. “Being a little over a million years old, the most extreme star R136a1 is already ‘middle-aged’ and has undergone an intense weight loss programme, shedding a fifth of its initial mass over that time, or more than fifty solar masses.”

If R136a1 replaced the Sun in our Solar System, it would outshine the Sun by as much as the Sun currently outshines the full Moon. “Its high mass would reduce the length of the Earth’s year to three weeks, and it would bathe the Earth in incredibly intense ultraviolet radiation, rendering life on our planet impossible,” says Raphael Hirschi from Keele University, who belongs to the team.

These super heavyweight stars are extremely rare, forming solely within the densest star clusters. Distinguishing the individual stars — which has now been achieved for the first time — requires the exquisite resolving power of the VLT’s infrared instruments.

The team also estimated the maximum possible mass for the stars within these clusters and the relative number of the most massive ones. “The smallest stars are limited to more than about eighty times more than Jupiter, below which they are ‘failed stars’ or brown dwarfs,” says team member Olivier Schnurr from the Astrophysikalisches Institut Potsdam. “Our new finding supports the previous view that there is also an upper limit to how big stars can get, although it raises the limit by a factor of two, to about 300 solar masses.”

Within R136, only four stars weighed more than 150 solar masses at birth, yet they account for nearly half of the wind and radiation power of the entire cluster, comprising approximately 100 000 stars in total. R136a1 alone energises its surroundings by more than a factor of fifty compared to the Orion Nebula cluster, the closest region of massive star formation to Earth.

Understanding how high mass stars form is puzzling enough, due to their very short lives and powerful winds, so that the identification of such extreme cases as R136a1 raises the challenge to theorists still further. “Either they were born so big or smaller stars merged together to produce them,” explains Crowther.

Stars between about 8 and 150 solar masses explode at the end of their short lives as supernovae, leaving behind exotic remnants, either neutron stars or black holes. Having now established the existence of stars weighing between 150 and 300 solar masses, the astronomers’ findings raise the prospect of the existence of exceptionally bright, “pair instability supernovae” that completely blow themselves apart, failing to leave behind any remnant and dispersing up to ten solar masses of iron into their surroundings. A few candidates for such explosions have already been proposed in recent years.

Not only is R136a1 the most massive star ever found, but it also has the highest luminosity too, close to 10 million times greater than the Sun. “Owing to the rarity of these monsters, I think it is unlikely that this new record will be broken any time soon,” concludes Crowther.

Combining observations made with ESO’s Very Large Telescope and NASA’s Chandra X-ray telescope, astronomers have uncovered the most powerful pair of jets ever seen from a stellar black hole. This object, also known as a microquasar, blows a huge bubble of hot gas, 1000 light-years across, twice as large and tens of times more powerful than other known microquasars. The discovery is reported this week in the journal Nature.

“We have been astonished by how much energy is injected into the gas by the black hole,” says lead author Manfred Pakull. “This black hole is just a few solar masses, but is a real miniature version of the most powerful quasars and radio galaxies, which contain black holes with masses of a few million times that of the Sun.”

Black holes are known to release a prodigious amount of energy when they swallow matter. It was thought that most of the energy came out in the form of radiation, predominantly X-rays. However, the new findings show that some black holes can release at least as much energy, and perhaps much more, in the form of collimated jets of fast moving particles. The fast jets slam into the surrounding interstellar gas, heating it and triggering an expansion. The inflating bubble contains a mixture of hot gas and ultra-fast particles at different temperatures. Observations in several energy bands (optical, radio, X-rays) help astronomers calculate the total rate at which the black hole is heating its surroundings.

The astronomers could observe the spots where the jets smash into the interstellar gas located around the black hole, and reveal that the bubble of hot gas is inflating at a speed of almost one million kilometres per hour.

“The length of the jets in NGC 7793 is amazing, compared to the size of the black hole from which they are launched,” says co-author Robert Soria. “If the black hole were shrunk to the size of a soccer ball, each jet would extend from the Earth to beyond the orbit of Pluto.”

This research will help astronomers understand the similarity between small black holes formed from exploded stars and the supermassive black holes at the centres of galaxies. Very powerful jets have been seen from supermassive black holes, but are thought to be less frequent in the smaller microquasar variety. The new discovery suggests that many of them may simply have gone unnoticed so far.

The gas-blowing black hole is located 12 million light-years away, in the outskirts of the spiral galaxy NGC 7793. From the size and expansion velocity of the bubble the astronomers have found that the jet activity must have been ongoing for at least 200 000 years.
Notes

Astronomers do not have yet any means of measuring the size of the black hole itself. The smallest stellar black hole discovered so far has a radius of about 15 km. An average stellar black hole of about 10 solar masses has a radius of about 30 km, while a “big” stellar black hole may have a radius of up to 300 km. This is still much smaller than the jets, which extend out to several hundreds light years on each side of the black hole, or about several thousand million million km!

The results appear this week in the journal Nature.

“HD209458b is definitely not a place for the faint-hearted. By studying the poisonous carbon monoxide gas with great accuracy we found evidence for a super wind, blowing at a speed of 5000 to 10 000 km per hour‚” says Ignas Snellen, who led the team of astronomers.

HD209458b is an exoplanet of about 60% the mass of Jupiter orbiting a solar-like star located 150 light-years from Earth towards the constellation of Pegasus (the Winged Horse). Circling at a distance of only one twentieth the Sun–Earth distance, the planet is heated intensely by its parent star, and has a surface temperature of about 1000 degrees Celsius on the hot side. But as the planet always has the same side to its star, one side is very hot, while the other is much cooler. “On Earth, big temperature differences inevitably lead to fierce winds, and as our new measurements reveal, the situation is no different on HD209458b,” says team member Simon Albrecht.

HD209458b was the first exoplanet to be found transiting: every 3.5 days the planet moves in front of its host star, blocking a small portion of the starlight during a three-hour period. During such an event a tiny fraction of the starlight filters through the planet’s atmosphere, leaving an imprint. A team of astronomers from the Leiden University, the Netherlands Institute for Space Research (SRON), and MIT in the United States, have used ESO’s Very Large Telescope and its powerful CRIRES spectrograph to detect and analyse these faint fingerprints, observing the planet for about five hours, as it passed in front of its star. “CRIRES is the only instrument in the world that can deliver spectra that are sharp enough to determine the position of the carbon monoxide lines at a precision of 1 part in 100 000,” says another team member Remco de Kok. “This high precision allows us to measure the velocity of the carbon monoxide gas for the first time using the Doppler effect.”

The astronomers achieved several other firsts. They directly measured the velocity of the exoplanet as it orbits its home star. “In general, the mass of an exoplanet is determined by measuring the wobble of the star and assuming a mass for the star, according to theory. Here, we have been able to measure the motion of the planet as well, and thus determine both the mass of the star and of the planet,” says co-author Ernst de Mooij.

Also for the first time, the astronomers measured how much carbon is present in the atmosphere of this planet. “It seems that H209458b is actually as carbon-rich as Jupiter and Saturn. This could indicate that it was formed in the same way,” says Snellen. “In the future, astronomers may be able to use this type of observation to study the atmospheres of Earth-like planets, to determine whether life also exists elsewhere in the Universe.”

ESO is releasing a beautiful image of the nearby galaxy Messier 83 taken by the HAWK-I instrument on ESO’s Very Large Telescope (VLT) at the Paranal Observatory in Chile. The picture shows the galaxy in infrared light and demonstrates the impressive power of the camera to create one of the sharpest and most detailed pictures of Messier 83 ever taken from the ground.

The galaxy Messier 83 is located about 15 million light-years away in the constellation of Hydra (the Sea Serpent). It spans over 40 000 light-years, only 40 percent the size of the Milky Way, but in many ways is quite similar to our home galaxy, both in its spiral shape and the presence of a bar of stars across its centre. Messier 83 is famous among astronomers for its many supernovae: vast explosions that end the lives of some stars. Over the last century, six supernovae have been observed in Messier 83 — a record number that is matched by only one other galaxy. Even without supernovae, Messier 83 is one of the brightest nearby galaxies, visible using just binoculars.

Messier 83 has been observed in the infrared part of the spectrum using HAWK-I, a powerful camera on ESO’s Very Large Telescope (VLT). When viewed in infrared light most of the obscuring dust that hides much of Messier 83 becomes transparent. The brightly lit gas around hot young stars in the spiral arms is also less prominent in infrared pictures. As a result much more of the structure of the galaxy and the vast hordes of its constituent stars can be seen. This clear view is important for astronomers looking for clusters of young stars, especially those hidden in dusty regions of the galaxy. Studying such star clusters was one of the main scientific goals of these observations. When compared to earlier images, the acute vision of HAWK-I reveals far more stars within the galaxy.

The combination of the huge mirror of the VLT, the large field of view and great sensitivity of the camera, and the superb observing conditions at ESO’s Paranal Observatory makes HAWK-I one of the most powerful near-infrared imagers in the world. Astronomers are eagerly queuing up for the chance to use the camera, which began operation in 2007, and to get some of the best ground-based infrared images ever of the night sky.

If life has evolved on Sat­urn’s frig­id moon, Ti­tan, it would be strange, smelly—and po­tent­ial­ly ex­plo­sive, new re­search sug­gests.

The con­clu­sions come from as­tro­bi­ol­o­gist Wil­liam Bains, who pre­s­ents his re­search at the Na­tional As­tron­o­my Meet­ing in Glas­gow, Scot­land on April 13.

“Hol­ly­wood would have prob­lems with these al­iens,” said Bains. “Beam one on­to the Star­ship En­ter­prise and it would boil and then burst in­to flames, and the fumes would kill eve­ry­one in range. Even a ti­ny whiff of its breath would smell un­be­lievably hor­ri­ble.

“But I think it is all the more in­ter­est­ing for that rea­son. Would­n’t it be sad if the most al­ien things we found in the gal­axy were just like us, but blue and with tail­s?” added Bains, re­fer­ring to the tall ex­tra­ter­res­tri­als from the mov­ie Av­a­tar.

Bains, whose re­search is car­ried out through Ru­fus Sci­en­tif­ic Ltd. in Cam­bridge, U.K. and the Mas­sachusetts In­sti­tute of Tech­nol­o­gy, is stu­dy­ing just how ex­treme life’s chem­is­try can be.

Life on Ti­tan, Sat­urn’s larg­est moon, is one of strang­er sce­nar­i­os un­der ex­amina­t­ion. Ti­tan is twice as large as our Moon and has a thick at­mos­phere of freez­ing, or­ange smog. At ten times our dis­tance from the Sun, it is a frig­id place, with a sur­face tem­per­a­ture of mi­nus 180 de­grees Cel­si­us (mi­nus 292 Fah­ren­heit). All the wa­ter is ice; the only liq­uids are meth­ane and eth­ane, fill­ing what sci­en­tists be­lieve are ponds and lakes.

“So, if life were to ex­ist on Ti­tan, it must have blood based on liq­uid meth­ane, not wa­ter. That means its whole chem­is­try is radic­ally dif­fer­ent. The mo­le­cules must be made of a wid­er va­ri­e­ty of el­e­ments than we use, but put to­geth­er in smaller molecules. It would al­so be much more chem­ic­ally re­ac­tive,” said Bains.

This blood would have to con­tain dis­solved chem­icals, but few chem­icals dis­solve easily in liq­uid meth­ane. Most mo­le­cules can’t dis­solve in it if they have more than six atoms not count­ing eas­ily-dis­solved hy­dro­gen. So a me­tab­o­lism run­ning in liq­uid meth­ane will have to be built of smaller mo­le­cules than in Earth bio­chem­is­try, which is typ­ic­ally built of mod­ules of around 10 atoms apart from hy­dro­gen.

You can only build around 3,400 dif­fer­ent mo­le­cules with­in the above-described lim­ita­t­ions on Ti­tan, Bains said. In con­trast, he added, one can build around 10 mil­lion or more dif­fer­ent mo­le­cules fit­ting Earth’s re­quired spe­cif­ica­t­ions, al­though only about 700 are ac­tu­ally used.

“The is­sue is not how many mo­le­cules you can make, but wheth­er you can make the col­lec­tion you need to as­sem­ble a me­tab­o­lism. It is like try­ing to find bits of wood in a lumber-yard to make a ta­ble. In the­o­ry you only need five. But you may have a lumber-yard full of off­cuts and still not find ex­actly the right five… so you need the po­ten­tial to make many more mo­le­cules than you ac­tu­ally need. Thus the six-atom chem­icals on Ti­tan would have to in­clude much more di­verse bond types [link­ing the atoms] and probably more di­verse el­e­ments, in­clud­ing sul­phur and phos­pho­rus.”

The el­e­ments would have to ap­pear in much more di­verse forms, as well as in forms that would be highly un­sta­ble on the Earth en­vi­ron­ment—hence the ex­plo­siveness, he added.

En­er­gy is anoth­er fac­tor that would af­fect the type of life that could evolve on Ti­tan. With sun­light a tenth of a per­cent as in­tense on Ti­tan’s sur­face as on the sur­face of Earth, en­er­gy is probably in short sup­ply. “Rapid move­ment or growth needs a lot of en­er­gy, so slow-growing, lichen-like or­gan­isms are pos­si­ble in the­o­ry, but ve­loci­rap­tors are pret­ty much ruled out,” said Bains.

Image Credit: © 2008 Karl Ko­foed

Oxfordshire Science Festival
This event is part of the Oxfordshire Science Festival 2010. For more information visit the website.

Combining observations from the CoRoT satellite and the ESO HARPS instrument, astronomers have discovered the first “normal” exoplanet that can be studied in great detail. Designated Corot-9b, the planet regularly passes in front of a star similar to the Sun located 1500 light-years away from Earth towards the constellation of Serpens (the Snake).

“This is a normal, temperate exoplanet just like dozens we already know, but this is the first whose properties we can study in depth,” says Claire Moutou, who is part of the international team of 60 astronomers that made the discovery. “It is bound to become a Rosetta stone in exoplanet research.”

“Corot-9b is the first exoplanet that really does resemble planets in our solar system,” adds lead author Hans Deeg. “It has the size of Jupiter and an orbit similar to that of Mercury.”

“Like our own giant planets, Jupiter and Saturn, the planet is mostly made of hydrogen and helium,” says team member Tristan Guillot, “and it may contain up to 20 Earth masses of other elements, including water and rock at high temperatures and pressures.”

Corot-9b passes in front of its host star every 95 days, as seen from Earth. This “transit” lasts for about 8 hours, and provides astronomers with much additional information on the planet. This is fortunate as the gas giant shares many features with the majority of exoplanets discovered so far.

“Our analysis has provided more information on Corot-9b than for other exoplanets of the same type,” says co-author Didier Queloz. “It may open up a new field of research to understand the atmospheres of moderate- and low-temperature planets, and in particular a completely new window in our understanding of low-temperature chemistry.”

More than 400 exoplanets have been discovered so far, 70 of them through the transit method. Corot-9b is special in that its distance from its host star is about ten times larger than that of any planet previously discovered by this method. And unlike all such exoplanets, the planet has a temperate climate. The temperature of its gaseous surface is expected to be between 160 degrees and minus twenty degrees Celsius, with minimal variations between day and night. The exact value depends on the possible presence of a layer of highly reflective clouds.

The CoRoT satellite, operated by the French space agency CNES, identified the planet after 145 days of observations during the summer of 2008. Observations with the very successful ESO exoplanet hunter — the HARPS instrument attached to the 3.6-metre ESO telescope at La Silla in Chile — allowed the astronomers to measure its mass, confirming that Corot-9b is indeed an exoplanet, with a mass about 80% the mass of Jupiter.

This finding is being published in this week’s edition of the journal Nature.

Phys­i­cists say they have de­tected the heav­i­est “an­ti-nu­cle­us” to date, a rare spec­i­men of a sort of mirror-image form of or­di­nary mat­ter.

The find­ing may shed light on cos­mic sym­me­tries, and asym­me­tries, that ex­plain why most of the an­ti­mat­ter orig­i­nally pro­duced at the birth of the uni­verse is gone, ac­cord­ing to sci­en­tists.

An an­ti­par­t­i­cle is a var­i­ant of one of the nor­mal build­ing blocks of mat­ter that has equal weight, but is op­po­site in elec­tri­cal charge and cer­tain oth­er re­spects, to its “nor­mal” par­t­i­cle coun­ter­part. As a nu­cle­us is the co­re of an or­di­nary at­om, an an­ti-nu­cle­us is the co­re of an “an­ti-at­om.”

The new­found an­ti-nu­cle­us al­so con­tains the first ex­am­ple of a smaller, equally ex­ot­ic com­po­nent build­ing block that phys­i­cists call an an­ti-strange quark.

The dis­cov­ery “may have un­prec­e­dent­ed con­se­quenc­es for our view of the world,” said the­o­ret­i­cal phys­i­cist Horst Stoe­cker, Vi­ce Pres­ident of the Helm­holtz As­socia­t­ion of Ger­man Na­tional Lab­o­r­a­to­ries. “This an­ti­mat­ter pushes open the door to new di­men­sions in the nu­clear chart — an idea that just a few years ago, would have been viewed as im­pos­si­ble.”

The find­ing, at the U.S. De­part­ment of En­er­gy’s Brook­ha­ven Na­tional Lab­o­r­a­to­ry in New York, may al­so help shed light on the work­ings of com­pact ce­les­tial ob­jects known as neu­tron stars, re­search­ers said.

The nu­cle­us of a nor­mal at­om on Earth con­sists of build­ing blocks called pro­tons and neu­trons, which in turn con­tain smaller com­po­nents known as quarks. These quarks ap­pear in two types, ar­bi­trarily called “up” and “down” va­ri­eties.

The stand­ard Per­i­od­ic Ta­ble of El­e­ments is a grid ar­ranged by num­ber of pro­tons, which de­ter­mine each chem­i­cal el­e­men­t’s prop­er­ties in its bas­ic in­ter­ac­tions with oth­er el­e­ments.

But phys­i­cists al­so use a more com­plex, three-di­men­sion­ chart which adds in­forma­t­ion on the dif­fer­ing num­ber of neu­trons that can oc­cur in sam­ples of each el­e­ment. The 3-D chart al­so in­di­cates a num­ber known as “s­trangeness,” which de­pends on the pres­ence of so-called “s­trange” quarks. Nu­clei con­taining one or more strange quarks are called hy­per­nu­clei.

For or­di­nary mat­ter with­out strange quarks, the strange­ness val­ue is ze­ro and the chart is flat. Hy­per­nu­clei are charted on a sep­a­rate grid, which is shown as if hov­er­ing above the stand­ard ta­ble. The new dis­cov­ery of strange an­ti­mat­ter with an an­ti­strange quark—an “an­ti­hy­per­nu­cle­us”—marks the first en­try be­low the stand­ard grid, sci­en­tists ex­plain.

The bi­zarre par­t­i­cle was de­tected as a re­sult of high-speed col­li­sions of gold nu­clei at the Rel­a­tiv­is­t Heavy Ion Col­lider, the Brook­ha­ven lab­o­r­a­to­ry’s at­om smash­er. The re­sults were pub­lished March 4 on the on­line edi­tion of the re­search jour­nal Sci­ence.

The study of the new an­ti­hyp­er­nu­cle­us al­so yields a val­u­a­ble sam­ple of hy­per­nu­clei, and has im­plica­t­ions for our un­der­stand­ing of the struc­ture of col­lapsed stars, called neu­tron stars, re­search­ers said. “The strange­ness val­ue could be non-ze­ro in the co­re of col­lapsed stars,” said Jin­hui Chen, one of the lead au­thors, of the Shang­hai In­sti­tute of Ap­plied Phys­ics and a post­doc­tor­al re­searcher at Kent State Uni­vers­ity in Ohio. The new mea­sure­ments “will help us dis­tin­guish be­tween mod­els that de­scribe these ex­ot­ic states of mat­ter.”

The find­ings al­so pave the way for ex­plor­ing vi­ola­t­ions of fun­da­men­tal sym­me­tries be­tween mat­ter and an­ti­mat­ter that oc­curred in the early uni­verse, mak­ing pos­si­ble the very ex­ist­ence of our world, phys­i­cists added.

Smashups be­tween at­omic nu­clei at the col­lider are be­lieved to fleet­ingly re­pro­duce con­di­tions that ex­isted a mi­nus­cule frac­tion of a sec­ond af­ter the Big Bang, which sci­en­tists be­lieve gave birth to the uni­verse as we know it some 13.7 bil­lion years ago.

In both events, quarks and an­ti­quarks emerge with equal abun­dance, ac­cord­ing to phys­i­cists. At the lab­o­r­a­to­ry, among the col­li­sion frag­ments that sur­vive to the fi­nal state, mat­ter and an­ti­mat­ter are still meas­ured as close to equally abun­dant. In con­trast, an­ti­mat­ter ap­pears to be largely ab­sent from the pre­s­ent-day uni­verse.

“Under­stand­ing pre­cisely how and why there’s a pre­dom­i­nance of mat­ter over an­ti­mat­ter re­mains a ma­jor un­solved prob­lem of physics,” said Brook­ha­ven phys­i­cist Zhang­bu Xu, anoth­er one of the lead au­thors. “A so­lu­tion will re­quire mea­sure­ments of sub­tle de­via­t­ions from per­fect sym­me­try be­tween mat­ter and an­ti­mat­ter, and there are good prospects for fu­ture an­ti­mat­ter mea­sure­ments at RHIC [Rel­a­tiv­is­t Heavy Ion Col­lider] to ad­dress this key is­sue.”

In a sin­gle col­li­sion of gold nu­clei at the col­lider, many hun­dreds of par­t­i­cles burst out at the point of the crash. Most of these don’t ac­tu­ally come from the pre­vi­ously ex­ist­ing, col­lid­ing ob­jects as such. Rath­er, they are formed from the en­er­gy of the col­li­sion, by the con­ver­sion of en­er­gy in­to mass in ac­cord­ance with Ein­stein’s fa­mous equa­t­ion E = mc2.

The par­t­i­cles leave tell­tale tracks in a de­tec­tor hooked up to the col­lider, called the STAR de­tec­tor. Sci­en­tists an­a­lyzed about a hun­dred mil­lion col­li­sions to spot the new an­ti­nu­clei, which aren’t di­rectly detecta­ble them­selves but are iden­ti­fa­ble through the byprod­ucts in­to which they dis­in­te­grate. Al­to­geth­er, 70 spec­i­mens of the new an­ti­nu­cle­us were de­tected.

STAR de­tec­tor sci­en­tists, who come from 54 in­sti­tu­tions in 13 coun­tries, say they should be able to disco­ver even heav­i­er an­ti­nu­clei soon. The­o­ret­i­cal phys­i­cist Stoe­cker and his team have pre­dicted that strange nu­clei around dou­ble the mass of the newly disco­vered state should be par­tic­u­larly sta­ble.

Using data from a NASA radar that flew aboard India’s Chandrayaan-1 spacecraft, scientists have detected ice deposits near the moon’s north pole. NASA’s Mini-SAR instrument, a lightweight, synthetic aperture radar, found more than 40 small craters with water ice. The craters range in size from 1 to 9 miles (2 to15 km) in diameter. Although the total amount of ice depends on its thickness in each crater, it’s estimated there could be at least 1.3 million pounds (600 million metric tons) of water ice.

“The emerging picture from the multiple measurements and resulting data of the instruments on lunar missions indicates that water creation, migration, deposition and retention are occurring on the moon,” said Paul Spudis, principal investigator of the Mini-SAR experiment at the Lunar and Planetary Institute in Houston. “The new discoveries show the moon is an even more interesting and attractive scientific, exploration and operational destination than people had previously thought.”

During the past year, the Mini-SAR mapped the moon’s permanently-shadowed polar craters that aren’t visible from Earth.
The radar uses the polarization properties of reflected radio waves to characterize surface properties. Results from the mapping showed deposits having radar characteristics similar to ice.

“After analyzing the data, our science team determined a strong indication of water ice, a finding which will give future missions a new target to further explore and exploit,” said Jason Crusan, program executive for the Mini-RF Program for NASA’s Space Operations Mission Directorate in Washington.

The Mini-SAR’s findings are being published in the journal Geophysical Research Letters. The results are consistent with recent findings of other NASA instruments and add to the growing scientific understanding of the multiple forms of water found on the moon. The agency’s Moon Mineralogy Mapper discovered water molecules in the moon’s polar regions, while water vapor was detected by NASA’s Lunar Crater Observation and Sensing Satellite, or LCROSS.

Mini-SAR and Moon Mineralogy Mapper are two of 11 instruments on the Indian Space Research Organization’s Chandrayaan-1. The Applied Physics Laboratory in Laurel, Md., performed the final integration and testing on Mini-SAR. It was developed and built by the Naval Air Warfare Center in China Lake, Calif., and several other commercial and government contributors.

For more information about NASA’s Mini-SAR, also known as Mini-RF, visit: http://www.nasa.gov/mini-rf

For more information about the Moon Mineralogy Mapper, visit: http://m3.jpl.nasa.gov

For more information about LCROSS, visit: http://www.nasa.gov/lcross

For more information about Chandrayaan-1, visit: http://www.isro.org/Chandrayaan

The Orion Nebula reveals many of its hidden secrets in a dramatic image taken by ESO’s new VISTA survey telescope. The telescope’s huge field of view can show the full splendour of the whole nebula and VISTA’s infrared vision also allows it to peer deeply into dusty regions that are normally hidden and expose the curious behaviour of the very active young stars buried there.

VISTA — the Visible and Infrared Survey Telescope for Astronomy — is the latest addition to ESO’s Paranal Observatory (eso0949). It is the largest survey telescope in the world and is dedicated to mapping the sky at infrared wavelengths. The large (4.1-metre) mirror, wide field of view and very sensitive detectors make VISTA a unique instrument. This dramatic new image of the Orion Nebula illustrates VISTA’s remarkable powers.

The Orion Nebula [1] is a vast stellar nursery lying about 1350 light-years from Earth. Although the nebula is spectacular when seen through an ordinary telescope, what can be seen using visible light is only a small part of a cloud of gas in which stars are forming. Most of the action is deeply embedded in dust clouds and to see what is really happening astronomers need to use telescopes with detectors sensitive to the longer wavelength radiation that can penetrate the dust. VISTA has imaged the Orion Nebula at wavelengths about twice as long as can be detected by the human eye.

As in the many visible light pictures of this object, the new wide field VISTA image shows the familiar bat-like form of the nebula in the centre of the picture as well as the fascinating surrounding area. At the very heart of this region lie the four bright stars forming the Trapezium, a group of very hot young stars pumping out fierce ultraviolet radiation that is clearing the surrounding region and making the gas glow. However, observing in the infrared allows VISTA to reveal many other young stars in this central region that cannot be seen in visible light.

Looking to the region above the centre of the picture, curious red features appear that are completely invisible except in the infrared. Many of these are very young stars that are still growing and are seen through the dusty clouds from which they form. These youthful stars eject streams of gas with typical speeds of 700 000 km/hour and many of the red features highlight the places where these gas streams collide with the surrounding gas, causing emission from excited molecules and atoms in the gas. There are also a few faint, red features below the Orion Nebula in the image, showing that stars form there too, but with much less vigour. These strange features are of great interest to astronomers studying the birth and youth of stars.

This new image shows the power of the VISTA telescope to image wide areas of sky quickly and deeply in the near-infrared part of the spectrum. The telescope is just starting to survey the sky and astronomers are anticipating a rich harvest of science from this unique ESO facility.

NASA’s Hubble Space Telescope has observed a mysterious X-shaped debris pattern and trailing streamers of dust that suggest a head-on collision between two asteroids. Astronomers have long thought the asteroid belt is being ground down through collisions, but such a smashup has never been seen before.

Asteroid collisions are energetic, with an average impact speed of more than 11,000 miles per hour, or five times faster than a rifle bullet. The comet-like object imaged by Hubble, called P/2010 A2, was first discovered by the Lincoln Near-Earth Asteroid Research, or LINEAR, program sky survey on Jan. 6. New Hubble images taken on Jan.
25 and 29 show a complex X-pattern of filamentary structures near the nucleus.

“This is quite different from the smooth dust envelopes of normal comets,” said principal investigator David Jewitt of the University of California at Los Angeles. “The filaments are made of dust and gravel, presumably recently thrown out of the nucleus. Some are swept back by radiation pressure from sunlight to create straight dust streaks. Embedded in the filaments are co-moving blobs of dust that likely originated from tiny unseen parent bodies.”

Hubble shows the main nucleus of P/2010 A2 lies outside its own halo of dust. This has never been seen before in a comet-like object. The nucleus is estimated to be 460 feet in diameter.

Normal comets fall into the inner regions of the solar system from icy reservoirs in the Kuiper belt and Oort cloud. As comets near the sun and warm up, ice near the surface vaporizes and ejects material from the solid comet nucleus via jets. But P/2010 A2 may have a different origin. It orbits in the warm, inner regions of the asteroid belt where its nearest neighbors are dry rocky bodies lacking volatile materials.

This leaves open the possibility that the complex debris tail is the result of an impact between two bodies, rather than ice simply melting from a parent body.

“If this interpretation is correct, two small and previously unknown asteroids recently collided, creating a shower of debris that is being swept back into a tail from the collision site by the pressure of sunlight,” Jewitt said.

The main nucleus of P/2010 A2 would be the surviving remnant of this so-called hypervelocity collision.

“The filamentary appearance of P/2010 A2 is different from anything seen in Hubble images of normal comets, consistent with the action of a different process,” Jewitt said. An impact origin also would be consistent with the absence of gas in spectra recorded using ground-based telescopes.

The asteroid belt contains abundant evidence of ancient collisions that have shattered precursor bodies into fragments. The orbit of P/2010 A2 is consistent with membership in the Flora asteroid family, produced by collisional shattering more than 100 million years ago.
One fragment of that ancient smashup may have struck Earth 65 million years ago, triggering a mass extinction that wiped out the dinosaurs.
But, until now, no such asteroid-asteroid collision has been caught “in the act.”

At the time of the Hubble observations, the object was approximately 180 million miles from the sun and 90 million miles from Earth. The Hubble images were recorded with the new Wide Field Camera 3 (WFC3), which is capable of detecting house-sized fragments at the distance of the asteroid belt.

For Hubble images and more information, visit:
http://www.nasa.gov/hubble

Astronomers using ESO’s Very Large Telescope have detected, in another galaxy, a stellar-mass black hole much farther away than any other previously known. With a mass above fifteen times that of the Sun, this is also the second most massive stellar-mass black hole ever found. It is entwined with a star that will soon become a black hole itself.

The stellar-mass black holes found in the Milky Way weigh up to ten times the mass of the Sun and are certainly not be taken lightly, but, outside our own galaxy, they may just be minor-league players, since astronomers have found another black hole with a mass over fifteen times the mass of the Sun. This is one of only three such objects found so far.

The newly announced black hole lies in a spiral galaxy called NGC 300, six million light-years from Earth. “This is the most distant stellar-mass black hole ever weighed, and it’s the first one we’ve seen outside our own galactic neighbourhood, the Local Group,” says Paul Crowther, Professor of Astrophysics at the University of Sheffield and lead author of the paper reporting the study. The black hole’s curious partner is a Wolf–Rayet star, which also has a mass of about twenty times as much as the Sun. Wolf–Rayet stars are near the end of their lives and expel most of their outer layers into their surroundings before exploding as supernovae, with their cores imploding to form black holes.

In 2007, an X-ray instrument aboard NASA’s Swift observatory scrutinised the surroundings of the brightest X-ray source in NGC 300 discovered earlier with the European Space Agency’s XMM-Newton X-ray observatory. “We recorded periodic, extremely intense X-ray emission, a clue that a black hole might be lurking in the area,” explains team member Stefania Carpano from ESA.

Thanks to new observations performed with the FORS2 instrument mounted on ESO’s Very Large Telescope, astronomers have confirmed their earlier hunch. The new data show that the black hole and the Wolf–Rayet star dance around each other in a diabolic waltz, with a period of about 32 hours. The astronomers also found that the black hole is stripping matter away from the star as they orbit each other.

“This is indeed a very ‘intimate’ couple,” notes collaborator Robin Barnard. “How such a tightly bound system has been formed is still a mystery.”

Only one other system of this type has previously been seen, but other systems comprising a black hole and a companion star are not unknown to astronomers. Based on these systems, the astronomers see a connection between black hole mass and galactic chemistry. “We have noticed that the most massive black holes tend to be found in smaller galaxies that contain less ‘heavy’ chemical elements,” says Crowther. “Bigger galaxies that are richer in heavy elements, such as the Milky Way, only succeed in producing black holes with smaller masses.” Astronomers believe that a higher concentration of heavy chemical elements influences how a massive star evolves, increasing how much matter it sheds, resulting in a smaller black hole when the remnant finally collapses.

In less than a million years, it will be the Wolf–Rayet star’s turn to go supernova and become a black hole. “If the system survives this second explosion, the two black holes will merge, emitting copious amounts of energy in the form of gravitational waves as they combine,” concludes Crowther. However, it will take some few billion years until the actual merger, far longer than human timescales. “Our study does however show that such systems might exist, and those that have already evolved into a binary black hole might be detected by probes of gravitational waves, such as LIGO or Virgo.”

Image credit: ESO/L. Calçada

Astronomers studying two exploding stars, or supernovae, have found evidence the blasts received an extra boost from newborn black holes. The supernovae were found to emit jets of particles traveling at more than half the speed of light.

Previously, the only catastrophic events known to produce such high-speed jets were gamma-ray bursts, the universe’s most luminous explosions. Supernovae and the most common type of gamma-ray bursts occur when massive stars run out of nuclear fuel and collapse. A neutron star or black hole forms at the star’s core, triggering a massive explosion that destroys the rest of the star.

“The explosion dynamics in typical supernovae limit the speed of the expanding matter to about three percent the speed of light,”
explained Chryssa Kouveliotou, an astrophysicst at NASA’s Marshall Space Flight Center in Huntsville, Ala., co-author of one of the new studies. “Yet, in these new objects, we’re tracking gas moving some 20 times faster than this.”

The new results, published in this week’s edition of the journal Nature, used observations from several space and ground-based observatories, including NASA’s SWIFT satellite.

The astronomers discovered the ultrafast debris by studying two supernovae at radio wavelengths using numerous facilities, including the National Science Foundation’s Very Large Array in Socorro, N.M., and the Robert C. Byrd Green Bank Telescope in West Virginia. One team used the real-time operating mode of the European Very Long Baseline Interferometry Network, an international collaboration of radio telescopes, to rapidly analyze data.

“In every respect, these objects look like gamma-ray bursts — except that they produced no gamma rays,” said Alicia Soderberg at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass.

Soderberg led a team that studied SN 2009bb, a supernova discovered in March 2009. It exploded in the spiral galaxy NGC 3278, located about 130 million light-years away.

The other object is SN 2007gr, which was first detected in August 2007 in the spiral galaxy NGC 1058, some 35 million light-years away. The study team, which included Kouveliotou and Alexander van der Horst, a NASA Postdoctoral Program Fellow in Huntsville, was led by Zsolt Paragi at the Netherlands-based Joint Institute for Very Long Baseline Interferometry in Europe.

The researchers searched for gamma-ray signals associated with the supernovae using archived records in the Gamma-Ray Burst Coordination Network located at NASA’s Goddard Space Flight Center in Greenbelt, Md. The project distributes and archives observations of gamma-ray bursts by NASA’s Swift spacecraft, the Fermi Gamma-ray Space Telescope and many others. However, no bursts coincided with the supernovae.

Unlike typical core-collapse supernovae, the stars that produce gamma-ray bursts possess what astronomers call a “central engine” — likely a nascent black hole — that drives particle jets clocked at more than 99 percent the speed of light.

By contrast, the fastest outflows detected from SN 2009bb reached 85 percent the speed of light and SN 2007gr reached more than 60 percent of light speed.

“These observations are the first to show some supernovae are powered by a central engine,” Soderberg said. “These new radio techniques now give us a way to find explosions that resemble gamma-ray bursts without relying on detections from gamma-ray satellites.”

Perhaps as few as one out of every 10,000 supernovae produce gamma rays that we detect as a gamma-ray burst. In some cases, the star’s jets may not be angled in a way to produce a detectable burst. In others, the energy of the jets may not be enough to allow them to overcome the overlying bulk of the star.

“We’ve now found evidence for the unsung crowd of supernovae — those with relatively dim and mildly relativistic jets that only can be detected nearby,” Kouveliotou said. “These likely represent most of the population.”

For more information, images and animation about this discovery, visit: http://www.nasa.gov/swift

View image here.

ESO has just released a stunning new image of the vast cloud known as the Cat’s Paw Nebula or NGC 6334. This complex region of gas and dust, where numerous massive stars are born, lies near the heart of the Milky Way galaxy, and is heavily obscured by intervening dust clouds.

Few objects in the sky have been as well named as the Cat’s Paw Nebula, a glowing gas cloud resembling the gigantic pawprint of a celestial cat out on an errand across the Universe. British astronomer John Herschel first recorded NGC 6334 in 1837 during his stay in South Africa. Despite using one of the largest telescopes in the world at the time, Herschel seems to have only noted the brightest part of the cloud, seen here towards the lower left.

NGC 6334 lies about 5500 light-years away in the direction of the constellation Scorpius (the Scorpion) and covers an area on the sky slightly larger than the full Moon. The whole gas cloud is about 50 light-years across. The nebula appears red because its blue and green light are scattered and absorbed more efficiently by material between the nebula and Earth. The red light comes predominantly from hydrogen gas glowing under the intense glare of hot young stars.

NGC 6334 is one of the most active nurseries of massive stars in our galaxy and has been extensively studied by astronomers. The nebula conceals freshly minted brilliant blue stars — each nearly ten times the mass of our Sun and born in the last few million years. The region is also home to many baby stars that are buried deep in the dust, making them difficult to study. In total, the Cat’s Paw Nebula could contain several tens of thousands of stars.

Particularly striking is the red, intricate bubble in the lower right part of the image. This is most likely either a star expelling large amount of matter at high speed as it nears the end of its life or the remnant of a star that already has exploded.

This new portrait of the Cat’s Paw Nebula was created from images taken with the Wide Field Imager (WFI) instrument at the 2.2-metre MPG/ESO telescope at the La Silla Observatory in Chile, combining images taken through blue, green and red filters, as well as a special filter designed to let through the light of glowing hydrogen.

In the new block­bust­er film Av­a­tar, hu­mans vis­it the hab­it­a­ble—and in­hab­it­ed—al­ien moon Pan­do­ra. Life-bearing moons like Pan­do­ra or the Star Wars for­est moon of En­dor are a sta­ple of sci­ence fic­tion.

But hab­it­a­ble moons may soon be­come sci­ence fact, and could per­haps even ex­ist around the same star that il­lu­mi­nates the fic­tional Pan­do­ra, as­tro­no­mers say.

“If Pan­do­ra ex­isted, we po­ten­tially could de­tect it and study its at­mos­phere in the next decade,” said Li­sa Kal­te­neg­ger of the Har­vard-Smith­son­ian Cen­ter for As­t­ro­phys­ics in Cam­bridge, Mass.

A new pa­per by Kal­te­neg­ger ar­gues that NASA’s new James Webb Space Tel­e­scope, to be launched in 2014, will be able to study their at­mos­pheres and de­tect key gas­es like car­bon di­ox­ide, ox­y­gen, and wa­ter va­por.

So far, plan­et searches have spot­ted hun­dreds of Ju­pi­ter-sized ob­jects in a range of or­bits. Such gi­ant gas plan­ets, while eas­i­er to de­tect, could not serve as homes for life as we know it. How­ev­er, sci­en­tists have spec­u­lat­ed wheth­er a rocky moon or­bit­ing a gas gi­ant could be life-friendly, if that plan­et or­bited with­in the star’s hab­it­a­ble zone, the re­gion warm enough for liq­uid wa­ter to ex­ist.

“All of the gas gi­ant plan­ets in our so­lar sys­tem have rocky and icy moons,” said Kal­te­neg­ger. “That raises the pos­si­bil­ity that al­ien Ju­pi­ters will al­so have moons. Some of those may be Earth-sized and able to hold on­to an at­mos­phere.”

NASA’s space-based Kep­ler tel­e­scope looks for plan­ets that cross in front of their host stars, which cre­ates a mini-eclipse and dims the star by a small but de­tecta­ble amount. Such a trans­it lasts only hours and re­quires ex­act align­ment of star and plan­et along our line of sight.

Once they have found an al­ien Ju­pi­ter, as­tro­no­mers can look for or­bit­ing moons. A moon’s gra­vity would tug on the plan­et and ei­ther speed or slow its trans­it, de­pend­ing on wheth­er the moon leads or trails the plan­et. The re­sult­ing trans­it dura­t­ion varia­t­ions would in­di­cate the moon’s ex­istence.

Once a moon is found, the next ob­vi­ous ques­tion would be: Does it have an at­mos­phere? If it does, those gas­es will ab­sorb a frac­tion of the star’s light dur­ing the trans­it, leav­ing a ti­ny, tell­tale fin­ger­print to the at­mos­phere’s com­po­si­tion.

The sig­nal is strongest for large worlds with hot, puffy at­mos­pheres, but an Earth-sized moon could be stud­ied if con­di­tions are just right. For ex­am­ple, the separa­t­ion of moon and plan­et needs to be large enough that we could catch just the moon in trans­it, while its plan­et is off to one side of the star.

Kal­te­neg­ger cal­cu­lat­ed what con­di­tions are best for ex­am­in­ing the at­mos­pheres of al­ien moons. She found that Al­pha Cen­tau­ri A, the sys­tem fea­tured in Av­a­tar, would be an ex­cel­lent tar­get.

“Al­pha Cen­tau­ri A is a bright, near­by star very si­m­i­lar to our Sun, so it gives us a strong sig­nal,” Kalteneg­ger ex­plained. “You would only need a hand­ful of trans­its to find wa­ter, ox­y­gen, car­bon di­ox­ide, and meth­ane on an Earth-like moon such as Pan­do­ra.”

While Al­pha Cen­tau­ri A of­fers tan­ta­liz­ing pos­si­bil­i­ties, small, dim, red dwarf stars are bet­ter tar­gets in the hunt for hab­it­a­ble plan­ets or moons, she added. The hab­it­a­ble zone for a red dwarf is clos­er to the star, which in­creases the prob­a­bil­ity of a trans­it.

As­tro­no­mers have de­bat­ed wheth­er tid­al lock­ing could be a prob­lem for red dwarfs. A plan­et close enough to be in the hab­it­a­ble zone would al­so be close enough for the star’s gra­vity to slow it un­til one side al­ways faces the star. (The same pro­cess keeps one side of the Moon al­ways fac­ing Earth.) One side of the plan­et then would be baked in con­stant sun­light, while the oth­er side would freeze in con­stant dark­ness.

An moon in the hab­it­a­ble zone would­n’t face this di­lem­ma. The moon would be tid­ally locked to its plan­et, not to the star, and there­fore would have reg­u­lar day-night cy­cles just like Earth. Its at­mos­phere would mod­er­ate tem­per­a­tures, and plant life would have a source of en­er­gy moon-wide.

“Alien moons or­bit­ing gas gi­ant plan­ets may be more likely to be hab­it­a­ble than tid­ally locked Earth-sized plan­ets or super-Earths,” said Kal­te­neg­ger. “We should cer­tainly keep them in mind as we work to­ward the ul­ti­mate goal of find­ing al­ien life.”

Scott Fleming of the University of Florida has also argued that a single habitable-zone gas giant could serve as a “signpost” for perhaps several habitable moons.

Kalteneg­ger’s pa­per is posted on­line at the arXiv database of Cor­nell Un­ivers­ity in New York.

Image Credit: Da­vid A. Aguilar, CfA

A far-off so­lar sys­tem seems to be form­ing from a strange dust whose make­up is un­like that of our and oth­er so­lar sys­tems, as­tro­no­mers say.

The researchers at the Univers­ity of Cal­i­for­nia Los An­ge­les found ev­i­dence for the forma­t­ion of young, rocky plan­ets from dust cir­cling a star some 500 light-years away. A light-year is the dis­tance light trav­els in a year.

“Un­til now, warm dust found around oth­er stars has been very si­m­i­lar in com­po­si­tion to as­ter­oi­dal or com­et­ary ma­te­ri­al in our So­lar Sys­tem,” said the uni­vers­ity’s Carl Melis, who led the re­search while a grad­u­ate stu­dent.

But this case is diff­er­ent, he said.

“Typic­ally, dust de­bris around oth­er stars, or our own Sun, is of the ol­i­vine, py­rox­ene, or sil­ica va­ri­e­ty, min­er­als com­monly found on Earth,” he noted. But this ma­te­ri­al “is not one of these dust types. We have yet to iden­ti­fy what spe­cies it is.”

Melis re­ported the find­ings last Wednes­day at the annual Amer­i­can As­tro­nom­i­cal So­ci­e­ty meet­ing in Wash­ing­ton, D.C.

The star, known as HD 131488, ap­pears to be sur­rounded by warm dust in a re­gion called the ter­res­tri­al plan­et zone, where tem­per­a­tures are si­m­i­lar to those on Earth, Melis said. He added that the dust seems to harbor rocky, emb­ry­onic planets that have re­cently coll­ided.

“What makes HD 131488 truly un­ique is the un­iden­ti­fied dust spe­cies re­leased from the col­lid­ing bod­ies as well as the pres­ence of cold dust far away from the star,” said as­tron­o­mer Ben­ja­min Zuck­er­man of the univers­ity, a co-author of the re­search. “These two char­ac­ter­is­tics make HD 131488 un­like any oth­er star with ev­i­dence for mas­sive quanti­ties of dust in its ter­res­tri­al plan­et zone.”

The re­search­ers an­a­lyzed the warm in­ner dust through in­fra­red im­ag­ing and spec­tros­co­py us­ing an in­stru­ment called T-ReCS on the Gem­i­ni South tel­e­scope in Chil­e. Spec­tros­co­py is the anal­y­sis of the com­po­si­tion of ob­jects us­ing the spec­trum of light they give off.

Melis and his team ar­gue that the most plau­si­ble ex­plana­t­ion for the un­usu­al abun­dance of warm dust is a re­cent col­li­sion of two rocky plan­e­tary mass bod­ies.

While the mys­te­ri­ous warm dust lies at a dis­tance from HD 131488 that is com­pa­ra­ble to the Earth-Sun separa­t­ion, the team al­so found cool­er dust about 45 times fur­ther out. This out­er dusty re­gion is anal­o­gous to the Kuiper Belt in our own So­lar Sys­tem where many mi­nor plan­ets or­bit the Sun just be­yond the or­bit of Nep­tune.

“The hot dust al­most cer­tainly came from a re­cent cat­a­stroph­ic col­li­sion be­tween two large rocky bod­ies in HD 131488’s in­ner plan­e­tary sys­tem,” Melis said. But the cool­er dust “is probably left over from plan­et forma­t­ion that took place far­ther away from HD 131488.”

HD 131488 lies in the di­rec­tion of the con­stella­t­ion Cen­tau­rus and is three times heav­i­er and 33 times more lu­mi­nous than our own Sun. The star is part of a ma­jor, south­ern-hem­i­sphere star form­ing re­gion known as the Upper-Cen­tau­rus-Lupus as­socia­t­ion whose mem­bers are be­lieved to be about 10 mil­lion years old. By con­trast, the Sun and Earth are about 4.6 bil­lion years old.

Radio astronomers have uncovered 17 millisecond pulsars in our galaxy by studying unknown high-energy sources detected by NASA’s Fermi Gamma-ray Space Telescope. The astronomers made the discovery in less than three months. Such a jump in the pace of locating these hard-to-find objects holds the promise of using them as a kind of “galactic GPS” to detect gravitational waves passing near Earth.

A pulsar is the rapidly spinning and highly magnetized core left behind when a massive star explodes. Because only rotation powers their intense gamma-ray, radio and particle emissions, pulsars gradually slow as they age. But the oldest pulsars spin hundreds of times per second — faster than a kitchen blender. These millisecond pulsars have been spun up and rejuvenated by accreting matter from a companion star.

“Radio astronomers discovered the first millisecond pulsar 28 years ago,” said Paul Ray at the Naval Research Laboratory in Washington.
“Locating them with all-sky radio surveys requires immense time and effort, and we’ve only found a total of about 60 in the disk of our galaxy since then. Fermi points us to specific targets. It’s like having a treasure map.”

Millisecond pulsars are nature’s most precise clocks, with long-term, sub-microsecond stability that rivals human-made atomic clocks.
Precise monitoring of timing changes in an all-sky array of millisecond pulsars may allow the first direct detection of gravitational waves — a long-sought consequence of Einstein’s relativity theory.

“The Global Positioning System uses time-delay measurements among satellite clocks to determine where you are on Earth,” explained Scott Ransom of the National Radio Astronomy Observatory in Charlottesville, Va. “Similarly, by monitoring timing changes in a constellation of suitable millisecond pulsars spread all over the sky, we may be able to detect the cumulative background of passing gravitational waves.”

The sources Fermi detected are not associated with any known gamma-ray emitting objects and did not show evidence of pulsing behavior.
However, scientists considered it likely that many of the unidentified sources would turn out to be pulsars.

For a more detailed look at radio wavelengths, Ray organized the Fermi Pulsar Search Consortium and recruited a handful of radio astronomers with expertise in using five of the world’s largest radio telescopes
– the National Radio Astronomy Observatory, Robert C. Byrd Green Bank Telescope in W.Va., the Parkes Observatory in Australia, the Nancay Radio Telescope in France, the Effelsberg Radio Telescope in Germany and the Arecibo Telescope in Puerto Rico.

After studying approximately 100 targets, and with a computationally intensive data analysis still under way, the discoveries have started to pour in.

“Other surveys took a decade to find as many of these pulsars as we have,” said Ransom, who led one of the discovery groups. “Having Fermi tell us where to look is a huge advantage.”

Four of the new objects are “black widow” pulsars, so called because radiation from the recycled pulsar is destroying the companion star that helped spin it up.

“Some of these stars are whittled down to masses equivalent to tens of Jupiters,” said Ray. “We’ve doubled the known number of these systems in the galaxy’s disk, and that will help us better understand how they evolve.”

NASA’s Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership, developed in collaboration with the Department of Energy, along with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden, and the U.S. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.