VizWorld.com

The University of Zurich partnered up with the University of California at Santa Cruz to run an impressive simulation of the creation of the universe, and visualized the result in this impressive movie now on YouTube.

For almost 20 years astrophysicists have been trying to recreate the formation of spiral galaxies such as our Milky Way realistically. Now astrophysicists from the University of Zurich present the world’s first realistic simulation of the formation of our home galaxy together with astronomers from the University of California at Santa Cruz. The new results were partly calculated on the computer of the Swiss National Supercomputing Center (CSCS) and show, for instance, that there has to be stars on the outer edge of the Milky Way.

Unfortunately, the video is only on YouTube in 360p.

via ERIS: World’s first realistic simulation of the formation of the Milky Way – YouTube.

Update 8/1: title changed for accuracy.

Science astronomy, space

Discovery News points us to Pasquale Tricario’s animations of today’s 2011MD asteroid that is passing dangerously close to the earth, even closer than the GPS satellite orbits.

“It is interesting to note that [2011 MD] will come closer than the GPS satellites, and also that it comes from the northern hemisphere, passes over the Earth’s south pole, and then is deflected so strongly that leaves the Earth back in the northern hemisphere,” Tricarico says on his website.

Check out his website for some more impressive animations like the one below.

When Asteroid ’2011 MD’ Zips Past Earth : Animation : Discovery News.

Science asteroid, astronomy

Earlier today (2:41AM EDT), the sun kicked up a massive solar flare, and luckily NASA’s Solar Dynamics Observatory caught the whole thing on film.

NASA’s Solar Dynamics Observatory spacecraft caught high-definition video of the flare in different wavelengths. The event registered as a Class M-2 solar flare, which is a medium-class sun storm that should not pose a danger to satellites or infrastructure on Earth.

The images are beautiful, but tomorrow this could wreak a little havoc when the resulting magnetic wave hits earth.

via Sun Unleashes ‘Spectacular’ & Powerful Eruption | Solar Flares, Sun Eruption & Sun Storms | Space Weather & Solar Cycle 24 | Space.com.

Graphics, Science astronomy, nasa, sun

The VLT Survey Telescope (VST), the latest addition to ESO’s Paranal Observatory, has made its first release of impressive images of the southern sky. The VST is a state-of-the-art 2.6-metre telescope, with the huge 268-megapixel camera OmegaCAM at its heart, which is designed to map the sky both quickly and with very fine image quality. It is a visible-light telescope that perfectly complements ESO’s VISTA infrared survey telescope. New images of the Omega Nebula and the globular cluster Omega Centauri demonstrate the VST’s power.

A New Telescope and Camera

The VLT Survey Telescope (VST) is the latest telescope to be added to ESO’s Paranal Observatory in the Atacama Desert of northern Chile. It is housed in an enclosure immediately adjacent to the four VLT Unit Telescopes on the summit of Cerro Paranal under the pristine skies of one of the best observing sites on Earth. The VST is a wide-field survey telescope with a field of view twice as broad as the full Moon. It is the largest telescope in the world designed to exclusively survey the sky in visible light. Over the next few years the VST and its camera OmegaCAM will make several very detailed surveys of the southern sky. All survey data will be made public.

“I am very pleased to see the impressive first images from the VST and OmegaCAM. The unique combination of the VST and the VISTA infrared survey telescope will allow many interesting objects to be identified for more detailed follow-up observations with the powerful telescopes of the VLT,” says Tim de Zeeuw, the ESO Director General.

“The VST project has overcome many difficulties but it is now repaying, with its excellent image quality, the expectations of the astronomical community and the efforts of the many people at INAF involved in its construction. I am very pleased to see the VST in operation,” adds Tommaso Maccacaro, the President of the Italian National Institute for Astrophysics (INAF).

The VST programme is a joint venture between the INAF–Osservatorio Astronomico di Capodimonte, Naples, Italy and ESO. INAF has designed and built the telescope with the collaboration of leading Italian industries and ESO is responsible for the enclosure and the civil engineering works at the site. OmegaCAM, the VST’s camera, was designed and built by a consortium including institutes in the Netherlands, Germany and Italy with major contributions from ESO. The new facility will be operated by ESO, which will also archive and distribute data from the telescope.

The VST is a state-of-the-art 2.6-metre aperture telescope with an active optics system to keep the mirrors perfectly positioned at all times. At its core, behind large lenses that ensure the best possible image quality, lies the 770 kg OmegaCAM camera, built around 32 CCD detectors, sealed in vacuum, that together create 268-megapixel images.

The First Images

Both the telescope and the camera have been designed to fully exploit the high quality skies at Paranal.

“The superb images now coming from VST and OmegaCAM are a tribute to the hard work of many groups around Europe over many years. We are now looking forward to a rich harvest of science and unexpected discoveries from the VST surveys,” adds Massimo Capaccioli, principal investigator of the VST project.

The first released image shows the spectacular star-forming region Messier 17, also known as the Omega Nebula or the Swan Nebula, as it has never been seen before. This dramatic region of gas, dust and hot young stars lies in the heart of the Milky Way in the constellation of Sagittarius (The Archer). The VST field of view is so large that the entire nebula, including its fainter outer parts, is captured — and retains its superb sharpness across the entire image.

The second released image may be the best portrait of the globular star cluster Omega Centauri ever made. This is the largest globular cluster in the sky, but the very wide field of view of VST and OmegaCAM can encompass even the faint outer regions of this spectacular object. This view, which includes about 300 000 stars, demonstrates the excellent resolution of VST.

The Surveys

The VST will make three public surveys over the next five years. The KIDS survey will image several regions of the sky away from the Milky Way. It will further the study of dark matter, dark energy and galaxy evolution, and find many new galaxy clusters and high-redshift quasars. The VST ATLAS survey will cover a larger area of sky and focus on understanding dark energy and supporting more detailed studies using the VLT and other telescopes. The third survey, VPHAS+, will image the central plane of the Milky Way to map the structure of the Galactic disc and its star formation history. VPHAS+ will yield a catalogue of around 500 million objects and will discover many new examples of unusual stars at all stages of their evolution.

The data volume produced by OmegaCAM will be large. About 30 terabytes of raw data will be produced per year and will flow back into data centres in Europe for processing. A novel and sophisticated software system has been developed at Groningen and Naples to handle the very large data flow. The end products from the processing will be huge lists of the objects found, as well as images, and these will be made available to astronomers worldwide for scientific analysis.

“The combination of large field of view, excellent image quality, and the very efficient operations scheme of the VST will produce an enormous wealth of information that will advance many fields of astrophysics,” concludes Konrad Kuijken, head of the OmegaCAM consortium.

Science astronomy, eso

An international team of astronomers has used ESO’s Very Large Telescope to carefully study the star VFTS 682 in the Large Magellanic Cloud, a small neighbouring galaxy to the Milky Way. By analysing the star’s light, using the FLAMES instrument on the VLT, they have found that it is about 150 times the mass of the Sun. Stars like these have so far only been found in the crowded centres of star clusters, but VFTS 682 lies on its own.

“We were very surprised to find such a massive star on its own, and not in a rich star cluster,” notes Joachim Bestenlehner, the lead author of the new study and a student at Armagh Observatory in Northern Ireland. “Its origin is mysterious.”

This star was spotted earlier in a survey of the most brilliant stars in and around the Tarantula Nebula in the Large Magellanic Cloud. It lies in a stellar nursery: a huge region of gas, dust and young stars that is the most active star-forming region in the Local Group of galaxies. At first glance VFTS 682 was thought to be hot, young and bright, but unremarkable. But the new study using the VLT has found that much of the star’s energy is being absorbed and scattered by dust clouds before it gets to Earth — it is actually more luminous than previously thought and among the brightest stars known.

Red and infrared light emitted by the star can get through the dust, but the shorter-wavelength blue and green light is scattered more and lost. As a result the star appears reddish, although if the view were unobstructed it would shine a brilliant blue-white.

As well as being very bright, VFTS 682 is also very hot, with a surface temperature of about 50 000 degrees Celsius. Stars with these unusual properties may end their short lives not just as a supernova, as is normal for high-mass stars, but just possibly as an even more dramatic long-duration gamma-ray burst, the brightest explosions in the Universe.

Although VFTS 682 seems to now be alone it is not very far away from the very rich star cluster RMC 136 (often called just R 136), which contains several similar “superstars” (eso1030).

“The new results show that VFTS 682 is a near identical twin of one of the brightest superstars at the heart of the R 136 star cluster,” adds Paco Najarro, another member of the team from CAB (INTA-CSIC, Spain).

Is it possible that VFTS 682 formed there and was ejected? Such “runaway stars” are known, but all are much smaller than VFTS 682 and it would be interesting to see how such a heavy star could be thrown from the cluster by gravitational interactions.

“It seems to be easier to form the biggest and brightest stars in rich star clusters,” adds Jorick Vink, another member of the team. “And although it may be possible, it is harder to understand how these brilliant beacons could form on their own. This makes VFTS 682 a really fascinating object.”

Science astronomy, eso

A star acquires much of its mass by accreting material from a disc. Accretion is probably not continuous but episodic. We have developed a method to include the effects of episodic accretion in simulations of star formation. Episodic accretion results in bursts of radiative feedback, during which a protostar is very luminous, and its surrounding disc is heated and stabilised. These bursts typically last only a few hundred years. In contrast, the lulls between bursts may last a few thousand years; during these lulls the luminosity of the protostar is very low, and its disc cools and fragments. Thus, episodic accretion enables the formation of low-mass stars, brown dwarfs and planetary-mass objects by disc fragmentation. If episodic accretion is a common phenomenon among young protostars, then the frequency and duration of accretion bursts may be critical in determining the low-mass end of the stellar initial mass function.

via : Dimitris Stamatellos

Science astronomy, scientific visualization

The spiral galaxy NGC 247 is one of the closest spiral galaxies of the southern sky. In this new view from the Wide Field Imager on the MPG/ESO 2.2-metre telescope in Chile large numbers of the galaxy’s component stars are clearly resolved and many glowing pink clouds of hydrogen, marking regions of active star formation, can be made out in the loose and ragged spiral arms.

NGC 247 is part of the Sculptor Group, a collection of galaxies associated with the Sculptor Galaxy (NGC 253, also shown in eso0902 and eso1025). This is the nearest group of galaxies to our Local Group, which includes the Milky Way, but putting a precise value on such celestial distances is inherently difficult.

To measure the distance from the Earth to a nearby galaxy, astronomers have to rely on a type of variable star called a Cepheid to act as a distance marker. Cepheids are very luminous stars, whose brightness varies at regular intervals. The time taken for the star to brighten and fade can be plugged into a simple mathematical relation that gives its intrinsic brightness. When compared with the measured brightness this gives the distance. However, this method isn’t foolproof, as astronomers think this period–luminosity relationship depends on the composition of the Cepheid.

Another problem arises from the fact that some of the light from a Cepheid may be absorbed by dust en route to Earth, making it appear fainter, and therefore further away than it really is. This is a particular problem for NGC 247 with its highly inclined orientation, as the line of sight to the Cepheids passes through the galaxy’s dusty disc.

However, a team of astronomers is currently looking into the factors that influence these celestial distance markers in a study called the Araucaria Project. The team has already reported that NGC 247 is more than a million light-years closer to the Milky Way than was previously thought, bringing its distance down to just over 11 million light-years.

Apart from the main galaxy itself, this view also reveals numerous galaxies shining far beyond NGC 247. In the upper right of the picture three prominent spirals form a line and still further out, far behind them, many more galaxies can be seen, some shining right through the disc of NGC 247.

This colour image was created from a large number of monochrome exposures taken through blue, yellow/green and red filters taken over many years. In addition exposures through a filter that isolates the glow from hydrogen gas have also been included and coloured red. The total exposure times per filter were 20 hours, 19 hours, 25 minutes and 35 minutes, respectively.

Science astronomy, eso

Using ESO’s Very Large Telescope an international team of astronomers has been able to study the short-lived disc of material around a young star that is in the early stages of making a planetary system. For the first time a smaller companion could be detected that may be the cause of the large gap found in the disc. Future observations will determine whether this companion is a planet or a brown dwarf.

Planets form from the discs of material around young stars, but the transition from dust disc to planetary system is rapid and few objects are caught during this phase . One such object is T Chamaeleontis (T Cha), a faint star in the small southern constellation of Chamaeleon that is comparable to the Sun, but very near the beginning of its life. T Cha lies about 350 light-years from the Earth and is only about seven million years old. Up to now no forming planets have been found in these transitional discs, although planets in more mature discs have been seen before.

“Earlier studies had shown that T Cha was an excellent target for studying how planetary systems form,” notes Johan Olofsson (Max Planck Institute for Astronomy, Heidelberg, Germany), one of the lead authors of two papers in the journal Astronomy & Astrophysics that describe the new work. “But this star is quite distant and the full power of the Very Large Telescope Interferometer (VLTI) was needed to resolve very fine details and see what is going on in the dust disc.”

The astronomers first observed T Cha using the AMBER instrument and the VLT Interferometer (VLTI). They found that some of the disc material formed a narrow dusty ring only about 20 million kilometres from the star. Beyond this inner disc, they found a region devoid of dust with the outer part of the disc stretching out into regions beyond about 1.1 billion kilometres from the star.

Nuria Huélamo (Centro de Astrobiología, ESAC, Spain), the lead author of the second paper takes up the story: “For us the gap in the dust disc around T Cha was a smoking gun, and we asked ourselves: could we be witnessing a companion digging a gap inside its protoplanetary disc?”

However, finding a faint companion so close to a bright star is a huge challenge and the team had to use the VLT instrument NACO in a novel and powerful way, called sparse aperture masking, to reach their goal. After careful analysis they found the clear signature of an object located within the gap in the dust disc, about one billion kilometres from the star — slightly further out than Jupiter is within our Solar System and close to the outer edge of the gap. This is the first detection of an object much smaller than a star within a gap in the planet-forming dust disc around a young star. The evidence suggests that the companion object cannot be a normal star but it could be either a brown dwarf surrounded by dust or, most excitingly, a recently formed planet.

Huélamo concludes: “This is a remarkable joint study that combines two different state-of-the-art instruments at ESO’s Paranal Observatory. Future observations will allow us to find out more about the companion and the disc, and also understand what fuels the inner dusty disc.”

Science astronomy, eso

The galaxy NGC 2841 – shown here in this NASA/ESA Hubble Space Telescope image, taken with the space observatory’s newest instrument, the Wide Field Camera 3 – currently has a relatively low star formation rate compared to other spirals. It is one of several nearby galaxies that have been specifically chosen for a new study in which a pick ’n’ mix of different stellar nursery environments and birth rates are being observed.

Star formation is one of the most important processes in shaping the Universe; it plays a pivotal role in the evolution of galaxies and it is also in the earliest stages of star formation that planetary systems first appear.

Yet there is still much that astronomers don’t understand, such as how do the properties of stellar nurseries vary according to the composition and density of the gas present, and what triggers star formation in the first place? The driving force behind star formation is particularly unclear for a type of galaxy called a flocculent spiral, such as NGC 2841 shown here, which features short spiral arms rather than prominent and well-defined galactic limbs.

In an attempt to answer some of these questions, an international team of astronomers is using the new Wide Field Camera 3 (WFC3) installed on the NASA/ESA Hubble Space Telescope to study a sample of nearby, but wildly differing, locations where stars are forming. The observational targets include both star clusters and galaxies, and star formation rates range from the baby-booming starburst galaxy Messier 82 to the much more sedate star producer NGC 2841.

WFC3 was installed on Hubble in May 2009 during Servicing Mission 4, and replaces the Wide Field and Planetary Camera 2. It is particularly well-suited to this new study, as the camera is optimised to observe the ultraviolet radiation emitted by newborn stars (shown by the bright blue clumps in this image of NGC 2841) and infrared wavelengths, so that it can peer behind the veil of dust that would otherwise hide them from view.

While the image shows lots of hot, young stars in the disc of NGC 2841, there are just a few sites of current star formation where hydrogen gas is collapsing into new stars. It is likely that these fiery youngsters destroyed the star-forming regions in which they were formed.
Notes

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

Image credit: NASA, ESA and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration Acknowledgment: M. Crockett and S. Kaviraj (Oxford University, UK), R. O’Connell (University of Virginia), B. Whitmore (STScI) and the WFC3 Scientific Oversight Committee.

Science astronomy, esa, hubble, nasa

The nebula Messier 78 takes centre stage in this image taken with the Wide Field Imager on the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile, while the stars powering the bright display take a backseat. The brilliant starlight ricochets off dust particles in the nebula, illuminating it with scattered blue light. Igor Chekalin was the overall winner of ESO’s Hidden Treasures 2010 astrophotography competition with his image of this stunning object.

Messier 78 is a fine example of a reflection nebula. The ultraviolet radiation from the stars that illuminate it is not intense enough to ionise the gas to make it glow — its dust particles simply reflect the starlight that falls on them.

Despite this, Messier 78 can easily be observed with a small telescope, being one of the brightest reflection nebulae in the sky. It lies about 1350 light-years away in the constellation of Orion (The Hunter) and can be found northeast of the easternmost star of Orion’s belt.

This new image of Messier 78 from the MPG/ESO 2.2-metre telescope at the La Silla Observatory is based on data selected by Igor Chekalin in his winning entry to the Hidden Treasures competition.

The pale blue tint seen in the nebula in this picture is an accurate representation of its dominant colour. Blue hues are commonly seen in reflection nebulae because of the way the starlight is scattered by the tiny dust particles that they contain: the shorter wavelength of blue light is scattered more efficiently than the longer wavelength red light.

This image contains many other striking features apart from the glowing nebula. A thick band of obscuring dust stretches across the image from the upper left to the lower right, blocking the light from background stars. In the bottom right corner, many curious pink structures are also visible, which are created by jets of material being ejected from stars that have recently formed and are still buried deep in dust clouds.

Two bright stars, HD 38563A and HD 38563B, are the main powerhouses behind Messier 78. However, the nebula is home to many more stars, including a collection of about 45 low mass, young stars (less than 10 million years old) in which the cores are still too cool for hydrogen fusion to start, known as T Tauri stars. Studying T Tauri stars is important for understanding the early stages of star formation and how planetary systems are created.

Remarkably, this complex of nebulae has also changed significantly in the last ten years. In February 2004 the experienced amateur observer Jay McNeil took an image of this region with a 75 mm telescope and was surprised to see a bright nebula — the prominent fan shaped feature near the bottom of this picture — where nothing was seen on most earlier images. This object is now known as McNeil’s Nebula and it appears to be a highly variable reflection nebula around a young star.

This colour picture was created from many monochrome exposures taken through blue, yellow/green and red filters, supplemented by exposures through an H-alpha filter that shows light from glowing hydrogen gas. The total exposure times were 9, 9, 17.5 and 15.5 minutes per filter, respectively.

This zoom sequence opens with a wide-field view of the Milky Way. We close in on the constellation of Orion and as we zoom in on to a region close to Orion’s famous belt, a fascinating region of dust and reflection nebulosity starts to come into view. The final scene reveals a colourful and richly detailed new image of Messier 78 taken with the Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile.

Credit:

ESO/S. Brunier/Chris Johnson, (cuttinedgeobservatory.com) and Igor Chekalin. Music: John Dyson (from the album Moonwind)

via : Reflected Glory

Science astronomy, esa