Saturday, March 30, 2013

Collision Course? A Comet Heads for Mars

Over the years, the spacefaring nations of Earth have sent dozens of probes and rovers to explore Mars.  Today there are three active satellites circling the red planet while two rovers, Opportunity and Curiosity, wheel across the red sands below.  Mars is dry, barren, and apparently lifeless. 

Soon, those assets could find themselves exploring a very different kind of world. 

"There is a small but non-negligible chance that Comet 2013 A1 will strike Mars next year in October of 2014," says Don Yeomans of NASA's Near-Earth Object Program at JPL.  "Current solutions put the odds of impact at 1 in 2000."  


In a new ScienceCast video, experts discuss what might happen if Comet 2013 A1 hits Mars. Play it

The nucleus of the comet is probably 1 to 3 km in diameter, and it is coming in fast, around 56 km/s (125,000 mph). "It if does hit Mars, it would deliver as much energy as 35 million megatons of TNT," estimates Yeomans. 

For comparison, the asteroid strike that ended the dinosaurs on Earth 65 million years ago was about three times as powerful, 100 million megatons. Another point of comparison is the meteor that exploded over Chelyabinsk, Russia, in February of 2013, damaging buildings and knocking people down. The Mars comet is packing 80 million times more energy than that relatively puny asteroid. 

An impact wouldn't necessarily mean the end of NASA's Mars program. But it would transform the program-- along with Mars itself. 

"I think of it as a giant climate experiment," says Michael Meyer, lead scientist for the Mars Exploration Program at NASA headquarters.  "An impact would loft a lot of stuff into the Martian atmosphere--dust, sand, water and other debris. The result could be a warmer, wetter Mars than we're accustomed to today."
Meyer worries that solar-powered Opportunity might have a hard time surviving if the atmosphere became opaque.  Nuclear-powered Curiosity, though, would carry on just fine.  He also notes that Mars orbiters might have trouble seeing the surface, for a while at least, until the debris begins to clear.

Mars Comet (solar panels, 200px)

Opportunity might have trouble observing the aftermath of a comet impact if dust in the air cuts sunlight to the rover's solar panels. More

A direct impact remains unlikely.  Paul Chodas of NASA's Near-Earth Object Program stresses that a 1 in 2000 chance of impact means there's a 1999 in 2000 chance of no impact.  "A near-miss is far more likely," he points out.

Even a near miss is a potentially big event.  The latest orbit solutions put the comet somewhere within 300,000 km of the red planet at closest approach.  That means Mars could find itself inside the comet's gassy, dusty atmosphere or "coma."  Visually, the comet would reach 0th magnitude, that is, a few times brighter than a 1st magnitude star, as seen from the Red Planet.

"Cameras on ALL of NASA's spacecraft currently operating at Mars should be able to take photographs of Comet 2013 A1," says Jim Bell, a planetary scientist and Mars imaging specialist at Arizona State University. "The issue with Mars Odyssey and the Mars Reconnaissance Orbiter will be the ability to point them in the right direction; they are used to looking down, not up. Mission designers will have to figure out if that is possible."

"The issue with the Opportunity and Curiosity rovers will be power for imaging at night," he continues. "Opportunity is solar powered and so would need to dip into reserve battery power to operate the cameras at night. Whether or not we will be able to do this will depend on how much power the rover is getting from dusty solar panels in the daytime. On the other hand, Curiosity is nuclear powered, so it could have better odds at night-time imaging."

Researchers will be keenly interested to see how the comet's atmosphere interacts with the atmosphere of Mars.  For one thing, there could be a meteor shower. "Analyzing the spectrum of disintegrating meteors could tell us something interesting about the chemistry of the upper atmosphere," notes Meyer.

Mars Comet (3D orbit, 200px)
Click to view an interactive 3D orbit of Comet 2013 A1. 

Another possibility is Martian auroras.  Unlike Earth, which has a global magnetic field that wraps around our entire planet, Mars is only magnetized in patches.  Here and there, magnetic umbrellas sprout out of the ground, creating a crazy-quilt of magnetic poles concentrated mainly in the southern hemisphere.  Ionized gases hitting the top of the Martian atmosphere could spark auroras in the canopies of the magnetic umbrellas. 

Even before the comet flyby was known, NASA had already decided to send a spacecraft to Mars to study the dynamics of the Martian atmosphere.  If the probe, named MAVEN (short for "Mars Atmosphere and Volatile Evolution"), is launched on time in November 2013, it would reach Mars just a few weeks before the comet in 2014. 

However, notes MAVEN's principal investigator Bruce Jakosky of the University of Colorado, the spacecraft won't be ready to observe the comet when it reaches Mars.  "It takes a while to get into our science mapping orbit, deploy the booms, turn on and test the science instruments--and so on," he explains. "MAVEN won't be fully operational until perhaps two weeks after the comet passes.  There are some effects that I would expect to linger for a relatively long period--especially if the comet hits Mars--and we will be able to observe those changes." 

Astronomers around the world are monitoring 2013 A1.  Every day, new data arrive to refine the comet's orbit.  As the error bars shrink, Yeomans expects a direct hit to be ruled out.  "The odds favor a flyby, not a collision," he says.  

Either way, this is going to be good. Stay tuned for updates as the comet approaches.

Author: Dr. Tony Phillips Production editor: Dr. Tony Phillips
Credit: Science@NASA

Friday, March 29, 2013

Masquerading as a double star

Credit: ESA/Hubble & NASA
Acknowledgement: Josh Barrington 

The object in this image is Jonckheere 900 or J 900, a planetary nebula — glowing shells of ionised gas pushed out by a dying star. Discovered in the early 1900s by astronomer Robert Jonckheere, the dusty nebula is small but fairly bright, with a relatively evenly spread central region surrounded by soft wispy edges.

Despite the clarity of this Hubble image, the two objects in the picture above can be confusing for observers. J 900’s nearby companion, a faint star in the constellation of Gemini, often causes problems for observers because it is so close to the nebula — when seeing conditions are bad, this star seems to merge into J 900, giving it an elongated appearance. Hubble’s position above the Earth’s atmosphere means that this is not an issue for the space telescope.

Astronomers have also mistakenly reported observations of a double star in place of these two objects, as the planetary nebula is quite small and compact.

J 900’s central star is only just visible in this image, and is very faint — fainter than the nebula’s neighbour. The nebula appears to display a bipolar structure, where there are two distinct lobes of material emanating from its centre, enclosed by a bright oval disc.

A version of this image was entered into the Hubble’s Hidden Treasures image processing competition by contestant Josh Barrington.

Source: ESA/Hubble

The Lost Galaxy

Credit: ESO

This image depicts the galaxy NGC 4535, in the constellation of Virgo (The Maiden), on a beautiful background full of many distant faint galaxies. Its almost circular appearance shows that we observe it nearly face-on. In the centre of the galaxy, there is a well-defined bar structure, with dust lanes that curve sharply before the spiral arms break from the ends of the bar. The bluish colour of the spiral arms points to the presence of a large number of hot young stars. In the centre, however, older and cooler stars give the bulge of the galaxy a yellower appearance.

This visible image was made with the FORS1 instrument on ESO’s 8.2-metre Very Large Telescope. The galaxy can also be seen through smaller amateur telescopes, and was first observed by William Herschel in 1785. When seen through a smaller telescope, NGC 4535 has a hazy, ghostly appearance, which inspired the prominent amateur astronomer Leland S. Copeland to name it “The Lost Galaxy” in the 1950s.

NGC 4535 is one of the largest galaxies in the Virgo Cluster, a massive cluster of as many as 2000 galaxies, about 50 million light-years away. Although the Virgo Cluster is not much larger in diameter than the Local Group — the galaxy cluster to which the Milky Way belongs —  it contains almost fifty times as many galaxies.

Source: ESO


Thursday, March 28, 2013

Hunting high-mass stars with Herschel

Annotated image of the W3 giant molecular cloud combining Herschel bands at 70 μm (blue), 160 μm (green) and 250 μm (red). The image spans 2 x 2 degrees. North is up and east is to the left.  Copyright: ESA/PACS & SPIRE consortia, A. Rivera-Ingraham & P.G. Martin, Univ. Toronto, HOBYS Key Programme (F. Motte).  More Images

In this new view of a vast star-forming cloud called W3, ESA’s Herschel space observatory tells the story of how massive stars are born.

W3 is a giant molecular cloud containing an enormous stellar nursery, some 6200 light-years away in the Perseus Arm, one of our Milky Way Galaxy’s main spiral arms.

Spanning almost 200 light-years, W3 is one of the largest star-formation complexes in the outer Milky Way, hosting the formation of both low- and high-mass stars. The distinction is drawn at eight times the mass of our own Sun: above this limit, stars end their lives as supernovas.

Dense, bright blue knots of hot dust marking massive star formation dominate the upper left of the image in the two youngest regions in the scene: W3 Main and W3 (OH). Intense radiation streaming away from the stellar infants heats up the surrounding dust and gas, making it shine brightly in Herschel’s infrared-sensitive eyes.

Older high-mass stars are also seen to be heating up dust in their environments, appearing as the blue regions labelled AFGL 333 in the lower left of the annotated version of the image, and the loop of KR 140, at bottom right.

Extensive networks of much colder gas and dust weave through the scene in the form of red filaments and pillar-like structures. Several of these cold cores conceal low-mass star formation, hinted at by tiny yellow knots of emission. 

By studying the two regions of massive star formation – W3 Main and W3 (OH) – scientists have made progress in solving one of the major conundrums in the birth of massive stars. That is, even during their formation, the radiation blasting away from these stars is so powerful that they should push away the very material they are feeding from. If this is the case, how can massive stars form at all? 

Observations of W3 point toward a possible solution: in these very dense regions, there appears to be a continuous process by which the raw material is moved around, compressed and confined, under the influence of clusters of young, massive protostars. 

Through their strong radiation and powerful winds, populations of young high-mass stars may well be able to build and maintain localised clumps of material from which they can continue to feed during their earliest and most chaotic years, despite their incredible energy output. 

Notes for Editors
“Herschel observations of the W3 GMC: Clues to the formation of clusters of high-mass stars,” by A. Rivera-Ingraham et al., is published in The Astrophysical Journal, 766, 85; doi:10.1088/0004-637X/766/2/85.

The study was part of the Guaranteed Time Key Programme HOBYS, the Herschel imaging survey of OB Young Stellar objects. 

The image presented here was taken in three colour bands centred on 70 μm (blue), 160 μm (green) and 250 μm (red). 

Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. 


For further information, please contact:
 
Markus Bauer




ESA Science and Robotic Exploration Communication Officer




Tel: +31 71 565 6799




Mob: +31 61 594 3 954




Email:
markus.bauer@esa.int

Alana Rivera-Ingraham
University of Toronto
Email:
rivera@cita.utoronto.ca

Göran Pilbratt


ESA Herschel Project Scientist




Tel: +31 71 565 3621




Email:
gpilbratt@rssd.esa.int

Wednesday, March 27, 2013

Young, Hot and Blue

Young stars in the open star cluster NGC 2547

The open star cluster NGC 2547 in the constellation of Vela
Wide-field view of the open star cluster NGC 2547

Videos

Zooming into the open star cluster NGC 2547
Zooming into the open star cluster NGC 2547

A close look at the young stars in the open star cluster NGC 2547
A close look at the young stars in the open star cluster NGC 2547  

Stars in the cluster NGC 2547

This pretty sprinkling of bright blue stars is the cluster NGC 2547, a group of recently formed stars in the southern constellation of Vela (The Sail). This image was taken using the Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile.

The Universe is an old neighbourhood — roughly 13.8 billion years old. Our galaxy, the Milky Way, is also ancient — some of its stars are more than 13 billion years old (eso0425). Nevertheless, there is still a lot of action: new objects form and others are destroyed. In this image, you can see some of the newcomers, the young stars forming the cluster NGC 2547.

But, how young are these cosmic youngsters really? Although their exact ages remain uncertain, astronomers estimate that NGC 2547’s stars range from 20 to 35 million years old. That doesn't sound all that young, after all. However, our Sun is 4600 million years old and has not yet reached middle age. That means that if you imagine that the Sun as a 40 year-old person, the bright stars in the picture are three-month-old babies.
Most stars do not form in isolation, but in rich clusters with sizes ranging from several tens to several thousands of stars. While NGC 2547 contains many hot stars that glow bright blue, a telltale sign of their youth, you can also find one or two yellow or red stars which have already evolved to become red giants. Open star clusters like this usually only have comparatively short lives, of the order of several hundred million years, before they disintegrate as their component stars drift apart.

Clusters are key objects for astronomers studying how stars evolve through their lives. The members of a cluster were all born from the same material at about the same time, making it easier to determine the effects of other stellar properties.

The star cluster NGC 2547 lies in the southern constellation of Vela (The Sail), about 1500 light-years from Earth, and is bright enough to be easily seen using binoculars. It was discovered in 1751 by the French astronomer Nicolas-Louis de Lacaille during an astronomical expedition to the Cape of Good Hope in South Africa, using a tiny telescope of less than two centimetres aperture.

Between the bright stars in this picture you can see plenty of other objects, especially when zooming in. Many are fainter or more distant stars in the Milky Way, but some, appearing as fuzzy extended objects, are galaxies, located millions of light-years beyond the stars in the field of view.

More information

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning the 39-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

Contacts

Richard Hook
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email:
rhook@eso.org

Astronomers Discover a New Kind of Supernova

This artist's conception shows the suspected progenitor of a new kind of supernova called Type Iax. Material from a hot, blue helium star at right is funneling toward a carbon/oxygen white dwarf star at left, which is embedded in an accretion disk. In many cases the white dwarf survives the subsequent explosion.  Credit: Christine Pulliam (CfA). High Resolution Image (jpg) - Low Resolution Image (jpg)

Cambridge, MA - Until now, supernovas came in two main "flavors." A core-collapse supernova is the explosion of a star about 10 to 100 times as massive as our sun, while a Type Ia supernova is the complete disruption of a tiny white dwarf. Today, astronomers are reporting their discovery of a new kind of supernova called Type Iax. This new class is fainter and less energetic than Type Ia. Although both varieties come from exploding white dwarfs, Type Iax supernovas may not completely destroy the white dwarf. 

"A Type Iax supernova is essentially a mini supernova," says lead author Ryan Foley, Clay Fellow at the Harvard-Smithsonian Center for Astrophysics (CfA). "It's the runt of the supernova litter." 

Foley and his colleagues identified 25 examples of the new type of supernova. None of them appeared in elliptical galaxies, which are filled with old stars. This suggests that Type Iax supernovas come from young star systems.
Based on a variety of observational data, the team concluded that a Type Iax supernova comes from a binary star system containing a white dwarf and a companion star that has lost its outer hydrogen, leaving it helium dominated. The white dwarf collects helium from the normal star. 

Researchers aren't sure what triggers a Type Iax. It's possible that the outer helium layer ignites first, sending a shock wave into the white dwarf. Alternatively, the white dwarf might ignite first due to the influence of the overlying helium shell. 

Either way, it appears that in many cases the white dwarf survives the explosion, unlike in a Type Ia supernova where the white dwarf is completely destroyed. "The star will be battered and bruised, but it might live to see another day," says Foley. 

Foley calculates that Type Iax supernovas are about a third as common as Type Ia supernovas. The reason so few have been detected is that the faintest are only one-hundredth as bright as a Type Ia. 

"Type Iax supernovas aren't rare, they're just faint," explains Foley. "For more than a thousand years, humans have been observing supernovas. This whole time, this new class has been hiding in the shadows." 

The Large Synoptic Survey Telescope, in which the CfA is a partner, could discover thousands of Type Iax supernovas over its lifetime. 

This research has been accepted for publication in The Astrophysical Journal and is available online.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

For more information, contact:

David A. Aguilar
Director of Public Affairs
Harvard-Smithsonian Center for Astrophysics
617-495-7462

daguilar@cfa.harvard.edu

 
Christine Pulliam
Public Affairs Specialist
Harvard-Smithsonian Center for Astrophysics
617-495-7463

cpulliam@cfa.harvard.edu




Tuesday, March 26, 2013

Galaxies the Way They Were

 A Hubble image of a field of distant galaxies. The CANDELS project has analyzed these and other data to study how galaxies form and evolve in the early universe.  Credit: NASA/Hubble.  Low Resolution Image (jpg)

Galaxies today come very roughly in two types: reddish, elliptically shaped collections of older stars, and bluer, spiral shaped objects dominated by young stars. The conventional wisdom is that the two types are related to one another, ellipticals representing an older, more evolved stage of galaxies. Astronomers have discovered during the past decade that these two categories seem also to apply to galaxies in the early universe. In particular, galaxies so distant from us that their light has been traveling for about eleven and one-half billion years, 84% of the age of the universe, also generally fall into these two groups. 

A major puzzle about these early galaxy types involves their specific properties: Red elliptical galaxies today are generally large in diameter, but in the distant cosmos the corresponding galaxies are much smaller - perhaps five times smaller than local ones of the same mass and much smaller than their blue, star-forming colleagues. If galaxies gain in mass with time, through collisions or other processes, they would be expected also to increase in size with time. Therefore, if the early red galaxies really do represent older stages of bluer objects, then as a class they should be more massive and larger, not smaller. 

The CANDELS project (Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey) has acquired a very large database of optical and infrared observations of distant galaxies. Writing in one of their new papers this month, CfA astronomer Matt Ashby and the CANDELS team propose a solution to the dilemma. They studied a set of galaxies whose light has been en route for between about nine and twelve billion years. Based on the measured rates of star formation in blue galaxies inferred from the radiation, they conclude that they have undergone collisions that induce star formation. That's what makes them shine exceptionally brightly. After a billion years or so, however, these starbursts leave many of them depleted in fuel, and as a result the galaxies shrink in size to become the compact red galaxies that are so puzzling. In the later universe star-forming galaxies have grown to considerably larger sizes, and their star formation is consequently spread across much larger volumes, so that the same quenching mechanism does not take place, leaving them to retain their sizes as ellipticals. 

 

Monday, March 25, 2013

Pluto's Undiscovered Satellites

Simulated image of the Pluto-Charon system. The Pluto-Charon binary (represented by the two largest white disks), the four small satellites -- P5, Nix, P4, and Hydra (represented by the four small white disks), and three smaller satellites (represented by the green disks) lie within an extended ensemble of solid particles shown as small blue dots. This configuration is the result after twenty years of a computer simulation with two million dust particles surrounding the known and predicted moons. On this short time scale, the small satellites clear out most of the dust particles along their orbits. On much longer time scales, satellites will clear dust from a larger fraction of their orbits.  Credit: Scott Kenyon and Ben Bromley.  Low Resolution Image (jpg)

In 2015, NASA's New Horizons spacecraft will encounter the binary planet Pluto-Charon and its coterie of small satellites. Discovered in June 2005, the satellites Nix and Hydra orbit Pluto-Charon at distances roughly 40 times (Nix) and 55 times (Hydra) larger than the radius of Pluto. Two other satellites, now known as P4 and P5, appeared on images from the Hubble Space Telescope in 2011-2012 and have similar orbits. With a planned closest approach to Pluto-Charon of only 10 Pluto radii, the New Horizons spacecraft must have a trajectory that avoids the satellites as it passes through the system. 

New computer simulations by Scott Kenyon of SAO and Ben Bromley of the University of Utah suggest New Horizons will have to dodge a few other satellites and may need to avoid a disk composed of small snowballs. Using a code developed to simulate the formation of a planetary system around a star like the Sun, Kenyon & Bromley explored whether satellites could grow in a disk of small particles surrounding Pluto-Charon. In their picture, the disk consists of icy material captured from the Kuiper Belt or left over from the giant impact thought to produce Pluto-Charon. Within this disk, small particles collide and merge into larger and larger objects which eventually become stable satellites orbiting Pluto-Charon.

The simulations typically form a few satellites with diameters of 10-30 km, similar to the sizes of Nix and Hydra, and many satellites with diameters of a few kilometers. After 10 million years of simulation time, all of the satellites orbit within a tenuous disk of very small particles with diameters of a centimeter or less. The accompanying image shows one outcome with a more massive disk and three predicted satellites lying outside the orbit of Hydra. 

Although the small sizes of the predicted satellites preclude detection with the Hubble Space Telescope, New Horizons can identify them. When the spacecraft is roughly 70 days away from Pluto, its camera will begin to search for satellites smaller than P5. A few weeks out, images might reveal a tenuous disk or an ensemble of rings outside the orbit of Hydra. The New Horizons observations will test Kenyon & Bromley's model and give us new clues about the origin of Pluto and the solar system. 



A New View of the Elephant’s Trunk Nebula

This image is composed of data from the INT Photometric H-Alpha Survey (IPHAS), including narrow-band H-Alpha (red) and broad-band Sloan r' (green) and Sloan i' (blue) filters. Image credit: Nick Wright (University of Hertfordshire, SAO), Geert Barentsen (University of Hertfordshire, Armagh Observatory). [ JPEG (8000×4000 pixels) ]

The Elephant’s Trunk nebula, formally known as IC1396A, is a cloud of gas and dust located 2400 light years from Earth in the constellation Cepheus. The Elephant Trunk is part of a larger region of ionized gas illuminated by a nearby massive O-type star (located outside the image to the left). Radiation and winds from this hot star compress and ionize the edges of cloud, resulting in the bright "ionization fronts" seen in this image. 

Young stars at very different stages of formation have been found both within and just outside the Elephant’s Trunk. Very young protostars, still accreting material from the surrounding nebula, are located inside the cloud, while fully formed stars have been found just in front of the ionization edges. This suggests that star formation has been proceeding sequentially through the cloud as a result of the ‘triggering’ effects of the hot star (Barentsen, 2011). On the order of 5% of the mass of gas and dust in the cloud has already been turned into protostars (Reach, 2004), and the process is continuing today. 

The Elephant’s Trunk is a popular target for amateur astrophotographers. If you have a camera and a telescope, why not go out and try to image this object yourself? 

More information:

 

  Contact: Javier Méndez  (Public Relations Officer)


Friday, March 22, 2013

Planck reveals an almost perfect Universe

Planck CMB
Copyright: ESA and the Planck Collaboration

Acquired by ESA’s Planck space telescope, the most detailed map ever created of the cosmic microwave background – the relic radiation from the Big Bang – was released today revealing the existence of features that challenge the foundations of our current understanding of the Universe. 

The image is based on the initial 15.5 months of data from Planck and is the mission’s first all-sky picture of the oldest light in our Universe, imprinted on the sky when it was just 380 000 years old. 

At that time, the young Universe was filled with a hot dense soup of interacting protons, electrons and photons at about 2700ºC. When the protons and electrons joined to form hydrogen atoms, the light was set free. As the Universe has expanded, this light today has been stretched out to microwave wavelengths, equivalent to a temperature of just 2.7 degrees above absolute zero. 

This ‘cosmic microwave background’ – CMB – shows tiny temperature fluctuations that correspond to regions of slightly different densities at very early times, representing the seeds of all future structure: the stars and galaxies of today. 

According to the standard model of cosmology, the fluctuations arose immediately after the Big Bang and were stretched to cosmologically large scales during a brief period of accelerated expansion known as inflation. 

Planck was designed to map these fluctuations across the whole sky with greater resolution and sensitivity than ever before. By analysing the nature and distribution of the seeds in Planck’s CMB image, we can determine the composition and evolution of the Universe from its birth to the present day. 

Copyright: ESA and the Planck Collaboration

 Overall, the information extracted from Planck’s new map provides an excellent confirmation of the standard model of cosmology at an unprecedented accuracy, setting a new benchmark in our manifest of the contents of the Universe.

But because precision of Planck’s map is so high, it also made it possible to reveal some peculiar unexplained features that may well require new physics to be understood.
“The extraordinary quality of Planck’s portrait of the infant Universe allows us to peel back its layers to the very foundations, revealing that our blueprint of the cosmos is far from complete. Such discoveries were made possible by the unique technologies developed for that purpose by European industry,” says Jean-Jacques Dordain, ESA’s Director General.

“Since the release of Planck’s first all-sky image in 2010, we have been carefully extracting and analysing all of the foreground emissions that lie between us and the Universe’s first light, revealing the cosmic microwave background in the greatest detail yet,” adds George Efstathiou of the University of Cambridge, UK. 

One of the most surprising findings is that the fluctuations in the CMB temperatures at large angular scales do not match those predicted by the standard model – their signals are not as strong as expected from the smaller scale structure revealed by Planck.

Planck enhanced anomalies
Copyright: ESA and the Planck Collaboration

Another is an asymmetry in the average temperatures on opposite hemispheres of the sky. This runs counter to the prediction made by the standard model that the Universe should be broadly similar in any direction we look. 

Furthermore, a cold spot extends over a patch of sky that is much larger than expected. 

The asymmetry and the cold spot had already been hinted at with Planck’s predecessor, NASA’s WMAP mission, but were largely ignored because of lingering doubts about their cosmic origin. 

“The fact that Planck has made such a significant detection of these anomalies erases any doubts about their reality; it can no longer be said that they are artefacts of the measurements. They are real and we have to look for a credible explanation,” says Paolo Natoli of the University of Ferrara, Italy. 

“Imagine investigating the foundations of a house and finding that parts of them are weak. You might not know whether the weaknesses will eventually topple the house, but you’d probably start looking for ways to reinforce it pretty quickly all the same,” adds François Bouchet of the Institut d’Astrophysique de Paris. 

One way to explain the anomalies is to propose that the Universe is in fact not the same in all directions on a larger scale than we can observe. In this scenario, the light rays from the CMB may have taken a more complicated route through the Universe than previously understood, resulting in some of the unusual patterns observed today. 

“Our ultimate goal would be to construct a new model that predicts the anomalies and links them together. But these are early days; so far, we don’t know whether this is possible and what type of new physics might be needed. And that’s exciting,” says Professor Efstathiou.

Copyright: ESA and the Planck Collaboration
New Cosmic Recipe

Beyond the anomalies, however, the Planck data conform spectacularly well to the expectations of a rather simple model of the Universe, allowing scientists to extract the most refined values yet for its ingredients. 

Normal matter that makes up stars and galaxies contributes just 4.9% of the mass/energy density of the Universe. Dark matter, which has thus far only been detected indirectly by its gravitational influence, makes up 26.8%, nearly a fifth more than the previous estimate. 

Conversely, dark energy, a mysterious force thought to be responsible for accelerating the expansion of the Universe, accounts for less than previously thought. 

Finally, the Planck data also set a new value for the rate at which the Universe is expanding today, known as the Hubble constant. At 67.15 kilometres per second per megaparsec, this is significantly less than the current standard value in astronomy. The data imply that the age of the Universe is 13.82 billion years.

“With the most accurate and detailed maps of the microwave sky ever made, Planck is painting a new picture of the Universe that is pushing us to the limits of understanding current cosmological theories,” says Jan Tauber, ESA’s Planck Project Scientist. 

“We see an almost perfect fit to the standard model of cosmology, but with intriguing features that force us to rethink some of our basic assumptions. 

“This is the beginning of a new journey and we expect that our continued analysis of Planck data will help shed light on this conundrum.”

Note for Editors

For further information, please contact:
 
Markus Bauer
ESA Science and Robotic Exploration Communication Officer
Tel: +31 71 565 6799
Mob: +31 61 594 3 954
Email:
markus.bauer@esa.int

George Efstathiou
University of Cambridge, UK
Tel: +44 1223 337530
Email:
gpe@ast.cam.ac.uk

François Bouchet
Institut d’Astrophysique de Paris, France
Tel: +33 1 44 32 80 95
Email:
bouchet@iap.fr

Paolo Natoli
University of Ferrara, Italy
Tel: +39 0532 97 42 44
Email:
Paolo.Natoli@unife.it

Jan Tauber

ESA Planck Project Scientist

Tel: +31 71 565 5342

Email:
Jan.Tauber@esa.int


Galactic glow worm

Credit: ESA/Hubble & NASA
Acknowledgement: Judy Schmidt

This charming and bright galaxy, known as IRAS 23436+5257, was captured by the the NASA/ESA Hubble Space Telescope. It is located in the northern constellation of Cassiopeia, which is named after an arrogant, vain, and yet beautiful mythical queen.

The twisted, wormlike structure of this galaxy is most likely the result of a collision and subsequent merger of two galaxies. Such interactions are quite common in the Universe, and they can range from minor interactions involving a satellite galaxy being caught by a spiral arm, to major galactic crashes. Friction between the gas and dust during a collision can have a major effect on the galaxies involved, morphing the shape of the original galaxies and creating interesting new structures.

When you look up at the calm and quiet night sky it is not always easy to picture it as a dynamic and vibrant environment with entire galaxies in motion, spinning like children’s toys and crashing into whatever crosses their path. The motions are, of course, extremely slow, and occur over millions or even billions of years.

The aftermath of these galactic collisions helps scientists to understand how these movements occur and what may be in store for our own Milky Way, which is on a collision course with a neighbouring galaxy, Messier 31.

A version of this image was entered into the Hubble’s Hidden Treasures image processing competition by contestant Judy Schmidt. Hidden Treasures was an initiative to invite astronomy enthusiasts to search the Hubble archive for stunning images that have never been seen by the general public. The competition has now closed and the results are published here.


Source: ESA/Hubble - Space Telescope


Thursday, March 21, 2013

Herschel Discovers Some of the Youngest Stars Ever Seen

Astronomers have found some of the youngest stars ever seen thanks to the Herschel space observatory, a European Space Agency mission with important NASA contributions. Dense envelopes of gas and dust surround the fledging stars known as protostars, making their detection difficult until now. The discovery gives scientists a window into the earliest and least understood phases of star formation. Image credit: NASA/ESA/ESO/JPL-Caltech/Max-Planck Institute for Astronomy. › Full image and caption

PASADENA, Calif. - Astronomers have found some of the youngest stars ever seen, thanks to the Herschel space observatory, a European Space Agency mission with important NASA contributions.

Observations from NASA's Spitzer Space Telescope and the Atacama Pathfinder Experiment (APEX) telescope in Chile, a collaboration involving the Max Planck Institute for Radio Astronomy in Germany, the Onsala Space Observatory in Sweden, and the European Southern Observatory in Germany, contributed to the findings.

Dense envelopes of gas and dust surround the fledging stars known as protostars, making their detection difficult. The 15 newly observed protostars turned up by surprise in a survey of the biggest site of star formation near our solar system, located in the constellation Orion. The discovery gives scientists a peek into one of the earliest and least understood phases of star formation.

"Herschel has revealed the largest ensemble of such young stars in a single star-forming region," said Amelia Stutz, lead author of a paper to be published in The Astrophysical Journal and a postdoctoral researcher at the Max Planck Institute for Astronomy in Heidelberg, Germany. "With these results, we are getting closer to witnessing the moment when a star begins to form."

Stars spring to life from the gravitational collapse of massive clouds of gas and dust. This changeover from stray, cool gas to the ball of super-hot plasma we call a star is relatively quick by cosmic standards, lasting only a few hundred thousand years. Finding protostars in their earliest, most short-lived and dimmest stages poses a challenge.

Astronomers long had investigated the stellar nursery in the Orion Molecular Cloud Complex, a vast collection of star-forming clouds, but had not seen the newly identified protostars until Herschel observed the region.

"Previous studies have missed the densest, youngest and potentially most extreme and cold protostars in Orion," Stutz said. "These sources may be able to help us better understand how the process of star formation proceeds at the very earliest stages, when most of the stellar mass is built up and physical conditions are hardest to observe."

Herschel spied the protostars in far-infrared, or long-wavelength, light, which can shine through the dense clouds around burgeoning stars that block out higher-energy, shorter wavelengths, including the light our eyes see.

The Herschel Photodetector Array Camera and Spectrometer (PACS) instrument collected infrared light at 70 and 160 micrometers in wavelength, comparable to the width of a human hair. Researchers compared these observations to previous scans of the star-forming regions in Orion taken by Spitzer. Extremely young protostars identified in the Herschel views but too cold to be picked up in most of the Spitzer data were further verified with radio wave observations from the APEX ground telescope.

"Our observations provide a first glimpse at protostars that have just begun to 'glow' at far-infrared wavelengths," said paper coauthor Elise Furlan, a postdoctoral research associate at the National Optical Astronomy Observatory in Tucson, Ariz.

Of the 15 newly discovered protostars, 11 possess very red colors, meaning their light output trends toward the low-energy end of the electromagnetic spectrum. This output indicates the stars are still embedded deeply in a gaseous envelope, meaning they are very young. An additional seven protostars previously seen by Spitzer share this characteristic. Together, these 18 budding stars comprise only five percent of the protostars and candidate protostars observed in Orion. That figure implies the very youngest stars spend perhaps 25,000 years in this phase of their development, a mere blink of an eye considering a star like our sun lives for about 10 billion years.

Researchers hope to document chronologically each stage of a star's development rather like a family album, from before birth to early infancy, when planets also take shape.

"With these recent findings, we add an important missing photo to the family album of stellar development," said Glenn Wahlgren, Herschel Program Scientist at NASA Headquarters in Washington. "Herschel has allowed us to study stars in their infancy."

Herschel is a European Space Agency mission, with science instruments provided by a consortia of European institutes with important participation by NASA. NASA's Herschel Project Office is based at the agency's Jet Propulsion Laboratory in Pasadena, Calif. JPL is a division of the California Institute of Technology, Pasadena.

For more about Herschel, visit: http://www.nasa.gov/herschel , http://www.esa.int/SPECIALS/Herschel/index.html and http://www.herschel.caltech.edu .


Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.clavin@jpl.nasa.gov

J.D. Harrington 202-358-5241
NASA Headquarters, Washington

j.d.harrington@nasa.gov

Wednesday, March 20, 2013

Spiral Beauty Graced by Fading Supernova


Spiral galaxy NGC 1637

The supernova 1999em in the galaxy NGC 1637 (annotated)

The spiral galaxy NGC 1637 in the constellation of Eridanus

Wide-field view of the sky around the spiral galaxy NGC 1637

Videos

Zooming in on the spiral galaxy NGC 1637
Zooming in on the spiral galaxy NGC 1637

A close look at the spiral galaxy NGC 1637
A close look at the spiral galaxy NGC 1637

About 35 million light-years from Earth, in the constellation of Eridanus (The River), lies the spiral galaxy NGC 1637. Back in 1999 the serene appearance of this galaxy was shattered by the appearance of a very bright supernova. Astronomers studying the aftermath of this explosion with ESO’s Very Large Telescope at the Paranal Observatory in Chile have provided us with a stunning view of this relatively nearby galaxy.

Supernovae are amongst the most violent events in nature. They mark the dazzling deaths of stars and can outshine the combined light of the billions of stars in their host galaxies.

In 1999 the Lick Observatory in California reported the discovery of a new supernova in the spiral galaxy NGC 1637. It was spotted using a telescope that had been specially built to search for these rare, but important cosmic objects [1]. Follow-up observations were requested so that the discovery could be confirmed and studied further. This supernova was widely observed and was given the name SN 1999em. After its spectacular explosion in 1999, the supernova’s brightness has been tracked carefully by scientists, showing its relatively gentle fading through the years.

The star that became SN 1999em was very massive — more than eight times the mass of the Sun — before its death. At the end of its life its core collapsed, which then created a cataclysmic explosion [2].

When they were making follow up observations of SN 1999em astronomers took many pictures of this object with the VLT, which were combined to provide us with this very clear image of its host galaxy, NGC 1637. The spiral structure shows up in this image as a very distinct pattern of bluish trails of young stars, glowing gas clouds and obscuring dust lanes.

Although at first glance NGC 1637 appears to be a fairly symmetrical object it has some interesting features. It is what astronomers classify as a lopsided spiral galaxy: the relatively loosely wound spiral arm at the top left of the nucleus stretches around it much further than the more compact and shorter arm at the bottom right, which appears dramatically slashed midway through its course.

Elsewhere in the image the view is scattered with much closer stars and more distant galaxies that happen to lie in the same direction.

Notes

[1] The supernova was discovered by the Katzman Automatic Imaging Telescope, at Lick Observatory on Mount Hamilton, California.

[2] SN 1999em is a core-collapse supernova classified more precisely as a Type IIp. The “p” stands for plateau, meaning supernovae of this type remain bright (on a plateau) for a relatively long period of time after maximum brightness.

More information

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning the 39-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

Links

Contacts

Richard Hook
ESO, La Silla, Paranal, E-ELT & Survey Telescopes Press Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email:
rhook@eso.org

Black hole-star pair orbiting at dizzying speed

video
MAXI J1659­–152
ESA’s XMM-Newton space telescope has helped to identify a star and a black hole that orbit each other at the dizzying rate of once every 2.4 hours, smashing the previous record by nearly an hour.

The black hole in this compact pairing, known as MAXI J1659-152, is at least three times more massive than the Sun, while its red dwarf companion star has a mass only 20% that of the Sun. The pair is separated by roughly a million kilometres.

The duo were discovered on 25 September 2010 by NASA’s Swift space telescope and were initially thought to be a gamma-ray burst. Later that day, Japan’s MAXI telescope on the International Space Station found a bright X-ray source at the same place.

More observations from ground and space telescopes, including XMM-Newton, revealed that the X-rays come from a black hole feeding off material ripped from a tiny companion.

Several regularly-spaced dips in the emission were seen in an uninterrupted 14.5 hour observation with XMM-Newton, caused by the uneven rim of the black hole’s accretion disc briefly obscuring the X-rays as the system rotates, its disc almost edge-on along XMM-Newton’s line of sight.

From these dips, an orbital period of just 2.4 hours was measured, setting a new record for black hole X-ray binary systems. The previous record-holder, Swift J1753.5–0127, has a period of 3.2 hours.

The black hole and the star orbit their common centre of mass. Because the star is the lighter object, it lies further from this point and has to travel around its larger orbit at a breakneck speed of two million kilometres per hour – it is the fastest moving star ever seen in an X-ray binary system. On the other hand, the black hole orbits at ‘only’ 150 000 km/h.

“The companion star revolves around the common centre of mass at a dizzying rate, almost 20 times faster than Earth orbits the Sun. You really wouldn’t like to be on such a merry-go-round in this Galactic fair!” says lead author Erik Kuulkers of ESA’s European Space Astronomy Centre in Spain.

His team also saw that they lie high above the Galactic plane, out of the main disc of our spiral Galaxy, an unusual characteristic shared only by two other black-hole binary systems, including Swift J1753.5–0127.
“These high galactic latitude locations and short orbital periods are signatures of a potential new class of binary system, objects that may have been kicked out of the Galactic plane during the explosive formation of the black hole itself,” says Dr Kuulkers.

Returning to MAXI J1659−152, the quick response of XMM-Newton was key in being able to measure the remarkably short orbital period of the system.

“Observations started at tea-time, just five hours after we received the request to begin taking measurements, and continued until breakfast the next day. Without this rapid response it would not have been possible to discover the fastest rotation yet known for any binary system with a black hole,” adds Norbert Schartel, ESA’s XMM-Newton project scientist.


“MAXI J1659−152: The shortest orbital period black-hole transient in outburst,” by E. Kuulkers et al. is published in Astronomy & Astrophysics, 552, A32 (2013).

For further information, please contact:
 
Markus Bauer 



ESA Science and Robotic Exploration Communication Officer




Tel: +31 71 565 6799





Mob: +31 61 594 3 954





Email: markus.bauer@esa.int




Erik Kuulkers
European Space Astronomy Centre, Madrid, Spain
Email: Erik.Kuulkers@esa.int

Norbert Schartel




XMM-Newton Project Scientist




Tel: +34 91 8131 184




Email: Norbert.Schartel@sciops.esa.int


Tuesday, March 19, 2013

LOFAR discovers new giant galaxy in all-sky survey


A team of astronomers led by ASTRON astronomer Dr. George Heald has discovered a previously unknown gigantic radio galaxy, using initial images from a new, ongoing all-sky radio survey. The galaxy was found using the powerful International LOFAR Telescope (ILT), built and designed by ASTRON. The team is currently performing LOFAR's first all-sky imaging survey, the Multi-frequency Snapshot Sky Survey (MSSS). While browsing the first set of MSSS images, Dr. Heald identified a new source the size of the full moon projected on the sky. The radio emission is associated with material ejected from one member of an interacting galaxy triplet system tens to hundreds of millions of years ago. The physical extent of the material is much larger than the galaxy system itself, extending millions of light years across intergalactic space. The MSSS survey is still ongoing, and is poised to discover many new sources like this one. 

The new galaxy is a member of a class of objects called Giant Radio Galaxies (GRGs). GRGs are a type of radio galaxy with extremely large physical size, suggesting that they are either very powerful or very old. LOFAR is an effective tool to find new GRGs like this one because of its extreme sensitivity to such large objects, combined with its operation at low frequencies that are well suited to observing old sources. 

The center of the new GRG is associated with one member of a galaxy triplet known as UGC 09555. The central galaxy is located at a redshift of z=0.054536, or 750 million light years from Earth. The central radio source was previously known and has a flat radio spectrum, typical of giant radio galaxies. 

LOFAR's MSSS survey is a concerted effort to image the entire northern sky at very low radio frequencies, between 30 and 160 MHz (wavelengths from 2m to 10m). The primary aim of the survey is to perform an initial shallow scan of the sky, in order to create an all-sky model that will support the calibration of much deeper observations. It is comparable in sensitivity and angular resolution to previous surveys with ‘classical' radio telescopes like the Very Large Array (VLA) in the USA, ASTRON's Westerbork Synthesis Radio Telescope (WSRT), and the Giant Metrewave Radio Telescope (GMRT) in India. MSSS is unique in that it operates at substantially lower frequencies, and is therefore poised to uncover new sources that were missed by previous surveys. Its broad bandwidth coverage is also novel in all-sky radio surveys, and will be used to provide additional information about the detected objects. 

The international team of astronomers that is performing the MSSS survey is made up of about fifty members from various institutes, mostly in the Netherlands, Germany, the UK, Poland, France and Italy.
 

 
For more information please contact:
 
Femke Boekhorst, PR & Communication. 
E-mail: boekhorst@astron.nl 
Phone: +31 521 595 204
Dr. George Heald, astronomer. 
E-mail: heald@astron.nl 
Phone: +31 521 595 100

Caption to the image: Overlay of the new GRG (blue-white colors) on an optical image from the Digitized Sky survey. The inset shows the central galaxy triplet (image from Sloan Digital Sky Survey). The image is about 2 Mpc across. 

More information about MSSS can be found on the ASTRON website: http://www.astron.nl/radio-observatory/lofar-msss/lofar-msss.

Kepler's Supernova Remnant: Famous Supernova Reveals Clues About Crucial Cosmic Distance Markers

 Kepler's Supernova Remnant
 Credit  X-ray: NASA/CXC/NCSU/M.Burkey et al; Optical: DSS 



This is the remnant of Kepler's supernova, the famous explosion that was discovered by Johannes Kepler in 1604. The red, green and blue colors show low, intermediate and high energy X-rays observed with NASA's Chandra X-ray Observatory, and the star field is from the Digitized Sky Survey.

As reported in our press release, a new study has used Chandra to identify what triggered this explosion. It had already been shown that the type of explosion was a so-called Type Ia supernova, the thermonuclear explosion of a white dwarf star. These supernovas are important cosmic distance markers for tracking the accelerated expansion of the Universe.

However, there is an ongoing controversy about Type Ia supernovas. Are they caused by a white dwarf pulling so much material from a companion star that it becomes unstable and explodes? Or do they result from the merger of two white dwarfs?

The new Chandra analysis shows that the Kepler supernova was triggered by an interaction between a white dwarf and a red giant star. The crucial evidence from Chandra was a disk-shaped structure near the center of the remnant. The researchers interpret this X-ray emission to be caused by the collision between supernova debris and disk-shaped material that the giant star expelled before the explosion. Another possibility was that the structure is just debris from the explosion.

The disk structure seen by Chandra in X-rays is very similar in both shape and location to one observed in the infrared by the Spitzer Space Telescope. This composite image shows Spitzer data in pink and Chandra data from iron emission in blue. The disk structure is identified with a label.

 X-ray Image (Elements)

This composite figure also shows a remarkably large and puzzling concentration of iron on one side of the center of the remnant but not the other. The authors speculate that the cause of this asymmetry might be the "shadow" in iron that was cast by the companion star, which blocked the ejection of material. Previously, theoretical work has suggested this shadowing is possible for Type Ia supernova remnants.

The authors also produced a video showing a simulation of the supernova explosion as it interacts with material expelled by the giant star companion. It was assumed that the bulk of this material was expelled in a disk-like structure, with a gas density that is ten times higher at the equator, running from left to right, than at the poles. This simulation was performed in two dimensions and then projected into three dimensions to give an image that can be compared with observations. The good agreement with observations supports their interpretation of the data.

These results were published online and in the February 10th, 2013 issue of The Astrophysical Journal.


Fast Facts for Kepler's Supernova Remnant:

Scale: Image is 12 arcmin across (45 light years)
Category: Supernovas & Supernova Remnants
Coordinates (J2000): RA 17h 30m 40.80s | Dec -21° 29' 11.00"
Constellation: Ophiuchus
Observation Date: 6 pointings between April and July, 2006
Observation Time: 205 hours 50 min (8 days 13 hours 50 min)
Obs. ID: 6714-6718, 7366
Instrument: ACIS
Also Known As: SN 1604, G004.5+06.8, V 843 Ophiuchi
References:  Burkey, M.T. et al, 2013, ApJ, 764, 63; arXiv:1212.4534
Color Code: X-ray (Red, Green, Blue); Optical (Grayscale)