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Hubble sees stellar incubator

Hubble image of NGC 2467

A newly-released Hubble Space Telescope image of the colourful star-forming region NGC 2467, where huge clouds of gas and dust are sprinkled with bright blue, hot young stars.

Strangely shaped dust clouds, resembling spilled liquids, are silhouetted against a colourful background of glowing gas in this newly released Hubble image.

The star-forming region NGC 2467 is a vast cloud of gas—mostly hydrogen—that serves as an incubator for new stars. Some of these youthful stars have emerged from the dense clouds where they were born and now shine brightly, hot and blue in this picture, but many others remain hidden.

Hints of the astrophysical processes at work are revealed within the image.

Hot young stars that recently formed from the cloud are emitting fierce ultraviolet radiation that is causing the whole scene to glow while also sculpting the environment and gradually eroding the gas clouds.

Studies have shown that most of the radiation comes from the single hot and brilliant massive star just above the centre of the image. Its fierce radiation has emptied the surrounding region and some of the next generation of stars are forming in the denser regions around the edge.

NGC 2467 is a similar but more distant cousin to the Orion Nebula, a famous “star-forming” region.

Such stellar nurseries can be seen out to considerable distances in the Universe, and their study is important in determining the distance and chemical composition of other galaxies.

Some galaxies contain huge star-forming regions, containing tens of thousands of stars.

NGC 2467 was discovered in the 19th century and lies in the southern constellation Puppis, which represents the poop deck of Jason’s fabled ship Argo from Greek mythology. NGC 2467 is thought to lie about 13,000 light-years from Earth.

Adapted from information issued by NASA / ESA / Orsola De Marco (Macquarie University).

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Stellar fireworks

A Hubble image of NGC 3603

NGC 3603 is a collection of stars surrounded by gas and dust, 20,000 light-years from Earth.

Looking like a  fireworks display, this young, glittering collection of stars  is surrounded by clouds of interstellar gas and dust—a nebula—the raw material for new stars.

The nebula is located 20,000 light-years away in the constellation Carina; the central cluster of huge, hot stars is called NGC 3603.

This environment is not as peaceful as it looks. Ultraviolet radiation and violent stellar winds have blown out an enormous cavity in the gas and dust enveloping the cluster, providing an unobstructed view of the cluster.

Most of the stars in the cluster were born around the same time but differ in size, mass, temperature, and colour. The course of a star’s life is determined by its mass, so a cluster of a given age will contain stars in various stages of their lives, giving an opportunity for detailed analyses of stellar life cycles.

NGC 3603 also contains some of the most massive stars known. These huge stars live fast and die young, burning through their hydrogen fuel quickly and ultimately ending their lives in supernova explosions.

Star clusters like NGC 3603 provide important clues to understanding the origin of massive star formation in the early, distant universe.

Astronomers also use massive clusters to study distant starbursts that occur when galaxies collide, igniting a flurry of star formation.

The proximity of NGC 3603 makes it an excellent lab for studying such distant and momentous events.

See the full-size image here (new window).

Adapted from information issued by STScI. Image credit: NASA, ESA, R. O’Connell (University of Virginia), F. Paresce (National Institute for Astrophysics, Bologna, Italy), E. Young (Universities Space Research Association/Ames Research Center), the WFC3 Science Oversight Committee, and the Hubble Heritage Team (STScI/AURA).

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Dragon of deep space

Visible and infrared images of M17 Swex

Before and after. The top half shows a visible light image of the region of space known as M17 Swex, while the bottom half is an infrared image of the same region, taken with the Spitzer Space Telescope. Details are revealed that are completely unseen at visible wavelengths.

A new infrared image from NASA’s Spitzer Space Telescope (above) shows what appears to be a dragon-shaped cloud of dust flying out from a bright explosion in space (bottom half), a creature that is entirely cloaked in shadow when viewed in visible part of the spectrum (top half).

The image has revealed that this dark cloud, called M17 SWex, is forming stars at a furious rate but has not yet spawned the most massive type of stars, known as O stars.

Such stellar behemoths, however, light up the M17 nebula at the image’s centre and have also blown a huge “bubble” in the gas and dust to the left of M17.

See the full-size infrared image here (1.1MB, will open in a new window).

The stars and gas in this region are passing though the Sagittarius spiral arm of the Milky Way (moving from right to left), touching off a galactic star-forming “domino effect.”

Stars are formed when interstellar gas clouds collapse in on themselves, often driven by pressure or shockwaves from outside.

The youngest episode of star formation is playing out inside the dusty dragon as it enters the spiral arm. Over time, this area will flare up like the bright M17 nebula to the left of the dragon, glowing in the light of young, massive stars.

The remnants of an older burst of star formation blew the bubble in the region to the far left, called M17 EB.

The different parts of M17 Swex

Stars and gas are moving through the Sagittarius spiral arm, sparking off star formation episodes.

The visible-light view of the area clearly shows the bright M17 nebula, as well as the glowing hot gas filling the “bubble” to its left. However the M17 SWex “dragon” is hidden within dust clouds that are opaque to visible light.

It takes an infrared view to catch the light from these shrouded regions and reveal the earliest stages of star formation.

Cold spacecraft takes hot pictures

The Spitzer Space Telescope comprises a 0.85-metre diameter telescope and three science instruments that perform imaging and spectroscopy in the 3–180 micron wavelength range.

Since infrared is primarily heat radiation, detectors are most sensitive to infrared light when they are kept extremely cold. Using the latest in large-format detector arrays, Spitzer has made observations that are more sensitive than any previous mission.

Artist's impression of the Spitzer Space Telescope

Artist's impression of the Spitzer Space Telescope (left) and a diagram showing its component parts.

Spitzer launched on 25 August 2003, but its coolant fluid has now run out. Now in an extended mission phase known as the Spitzer Warm Mission, the telescope continues to operate, but with some small limitations due to its not-as-cold-anymore status.

The telescope is surrounded by an outer shell that radiates heat to cold space in the anti-Sun direction, and is shielded from the Sun by the solar panel assembly. Intermediate shields intercept heat from the solar panel and the spacecraft bus, or main structure.

The outer shell and inner, middle, and outer shields were vapour cooled—ie. the cold helium vapour from the helium tank was used to carry away the heat from these structures—prior to the expiration of the coolant fluid.

The spacecraft bus contains the subsystems required for housekeeping and control engineering: telecommunications, reaction control, pointing control, command and data handling, and power. The star tracker and gyro package is mounted on the spacecraft bus. The main antenna is located at the rear of the spacecraft bus. Control thrusters are located on outriggers from the spacecraft bus.

Adapted from information issued by NASA / JPL-Caltech / Penn State / DSS.

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Cosmic watercolour

R Corona Australis nebula

The R Corona Australis nebula is a complex mix of gas and dust 420 light-years from Earth, where young stars are beginning their lives.

  • R Corona Australis starbirth region
  • 420 light-years from Earth
  • Gas glows blue from reflected starlight

This magnificent view of the region around the star R Coronae Australis was created from images taken with the Wide Field Imager (WFI) at the European Southern Observatory’s (ESO) La Silla Observatory in Chile.

R Coronae Australis lies at the heart of a nearby star-forming region and is surrounded by a delicate bluish “reflection” nebula embedded in a huge dust cloud.

The new image—a combination of twelve separate pictures taken through red, green and blue filters—reveals surprising new details in this dramatic area of sky, which spans roughly the width of the full Moon.

The nebula is located some 420 light-years away in the small constellation of Corona Australis (the Southern Crown). The complex is named after the star R Coronae Australis, which lies at the centre of the image. It is one of several stars in this region that belong to the class of very young stars that vary in brightness and are still surrounded by the clouds of gas and dust from which they formed.

See the full-size version of the image here (new window).

Colours of the night

The intense radiation given off by these hot young stars interacts with the gas surrounding them and is either reflected or re-emitted at a different wavelength.

These complex processes, determined by the physics of interstellar gas and the properties of the stars, are responsible for the magnificent colours of nebulae. The light blue nebulosity seen in this picture is mostly due to the reflection of starlight off small dust particles.

The young stars in the R Coronae Australis complex are similar in mass to the Sun and do not emit enough ultraviolet light to ionise a substantial fraction of the surrounding hydrogen. This means that the cloud does not glow with the characteristic pink colour seen in many star-forming regions.

The image below shows a wider view of the R Corona Australis region. See the full-size version here (new window).

R Corona Australis nebula

A wider view of the R Corona Australis region. A globular star cluster, NGC 6723, is just above and to the right.

A prominent dark “lane” crosses the image from the centre to the bottom left. Here the visible light emitted by the stars that are forming inside the cloud is completely absorbed by the dust. These stars could only be detected by observing at longer wavelengths, by using a camera that can detect infrared radiation.

Adapted from information issued by ESO.

Telescope sees shocking blue “bullet”

Supernova remnant cloud N49 in the Large Magellanic Cloud galaxy.

Supernova remnant cloud N49 in the Large Magellanic Cloud galaxy. The blue blob in the lower right corners is being ejected at a speed of 8 million km per hour.

  • Supernova remnant in a neighbouring galaxy
  • X-ray data sees a “bullet-shaped” object shooting out
  • “Bullet” is travelling at 8 million km per hour

This beautiful composite image shows N49, the aftermath of a supernova explosion in the Large Magellanic Cloud (one of the Milky Way’s neighbour galaxies).

A new, long observation from NASA’s Chandra X-ray Observatory, shown as blue colours, reveals evidence for a “bullet-shaped” object being blown out of a debris field left over from an exploded star.

In order to detect this bullet—which can be seen as the blue “blob” in the lower right hand corner of the image—a team of researchers led by Sangwook Park of Penn State University used Chandra to observe N49 for over 30 hours. The bullet is rich in silicon, sulphur and neon.

The detection of this bullet shows that the explosion that destroyed the star was highly asymmetric.

The bullet is travelling at a high speed of about 8 million kilometres per hour away from a bright point source in the upper left part of N49. This bright source may be a so-called soft gamma ray repeater (SGR), a source that emits bursts of gamma rays and X-rays.

Artist's impression of the Chandra X-ray Observatory

Artist's impression of the Chandra X-ray Observatory.

Supernova shockwave

A leading explanation for SGRs is that they are neutron stars with extremely powerful magnetic fields. Since neutron stars are often created in supernova explosions, an association between SGRs and supernova remnants is not unexpected. This case is strengthened by the apparent alignment between the bullet’s path and the bright X-ray source.

However, the new Chandra data also shows that the bright source is more obscured by gas than expected if it really lies inside the supernova remnant. In other words, it is possible that the bright X-ray source actually lies beyond the remnant and is projected along the line of sight.

Another possible bullet is located on the opposite side of the remnant, but it is harder to see in the image because it overlaps with the bright emission—described below—from the shock-cloud interaction.

Optical data from the Hubble Space Telescope (yellow and purple colouring) shows bright filaments where the shock wave generated by the supernova is crashing into the densest regions of nearby clouds of cool, molecular gas.

Using the new Chandra data, the age of N49—as it appears in the image—is thought to be about 5,000 years, and the energy of the explosion is estimated to have been about twice that of an average supernova. These preliminary results suggest that the original explosion was caused by the collapse of a massive star.

Adapted from information issued by Chandra X-ray Centre.

Hubble’s 20th birthday image

Hubble Space Telescope image of part of the Carina Nebula

This turbulent cosmic pinnacle lies within a tempestuous stellar nursery called the Carina Nebula, located 7,500 light-years away in the southern constellation of Carina. The image celebrates the 20th anniversary of Hubble's launch and deployment into an orbit around the Earth.

The best recognised, longest-lived and most prolific space observatory zooms past a milestone of 20 years of operation.

On April 24, 1990, the space shuttle and crew of STS-31 were launched to deploy the NASA/ESA Hubble Space Telescope into a low-Earth orbit. What followed was one of the most remarkable sagas of the space age.

Hubble’s unprecedented capabilities have made it one of the most powerful science instruments ever conceived by humans, and certainly the one most embraced by the public. Hubble’s discoveries have revolutionised nearly all areas of current astronomical research, from planetary science to cosmology. And, its pictures are unmistakably out of this world.

At times Hubble’s starry odyssey has played out like a space soap opera: with broken equipment, a bleary-eyed primary mirror and even a Space Shuttle rescue/repair mission cancellation.

But the ingenuity and dedication of Hubble scientists, engineers, and NASA and ESA astronauts have allowed the observatory to rebound time and time again. Its crisp vision continues to challenge scientists with exciting new surprises and to enthral the public with ever more evocative colour images.

NASA, ESA and the Space Telescope Science Institute (STScI) are celebrating Hubble’s journey of exploration with a stunning new picture.

The brand new Hubble anniversary image highlights a small portion of one of the largest observable regions of starbirth in the galaxy, the Carina Nebula. (See the large version here.) Towers of cool hydrogen laced with dust rise from the wall of the nebula.

The scene is reminiscent of Hubble’s classic Pillars of Creation photo from 1995, but even more striking in appearance.

The image captures the top of a pillar of gas and dust, three light-years tall, which is being eaten away by the brilliant light from nearby bright stars. The pillar is also being pushed apart from within, as infant stars buried inside it fire off jets of gas that can be seen streaming from towering peaks like arrows sailing through the air.

The Hubble Space Telescope in orbit

The Hubble Space Telescope in orbit

Hubble’s public involvement

Another exciting component of the anniversary will be the launch of the revamped European website for Hubble, spacetelescope.org. ESA will also be sponsoring the Hubble Pop Culture Contest that calls for fans to search for examples of the observatory’s presence in everyday life (http://www.spacetelescope.org/projects/20anniversary/hubblepopculture/).

Hubble fans worldwide are being invited to share the ways in which the telescope has affected them. They can send an e-mail, post a Facebook message (to http://www.facebook.com/hubblespacetelescope) or use the Twitter hashtag #hst20. Or, they can visit the “Messages to Hubble” page on http://hubblesite.org, type in their entry and read selections from other messages that have been received.

Fan messages will be stored in the Hubble data archive along with the telescope’s many terabytes of science data. Future researchers will be able to read these messages and understand how Hubble had such an impact on the world.

To date, Hubble has looked at over 30,000 celestial targets and amassed over half a million pictures in its archive.

The last heroic astronaut-servicing mission to Hubble in May 2009 made the telescope 100 times more powerful than when it was launched. In addition to its irreplaceable scientific importance, Hubble brings cosmic wonders into millions of homes and schools every day.

Adapted from information issued by ESA. Image credit: NASA, ESA, M. Livio and the Hubble 20th Anniversary Team (STScI).

Young stars shine in Orion

Part of the Orion Nebula

Part of the Orion Nebula, imaged by NASA's Spitzer Space Telescope. The region contains many young stars.

Astronomers have their eyes on a hot group of young stars, watching their every move like the paparazzi.

A new infrared image from NASA’s Spitzer Space Telescope shows the bustling star-making colony of the Orion nebula, situated in the hunter’s sword of the famous constellation.

Like Hollywood starlets, the cosmic orbs don’t always shine their brightest, but vary over time. Spitzer is watching the stellar show, helping scientists learn more about why the stars change, and to what degree planet formation might play a role.

“This is an exploratory project. Nobody has done this before at a wavelength sensitive to the heat from dust circling around so many stars,” said John Stauffer, the principal investigator of the research at NASA’s Spitzer Science Centre, located at the California Institute of Technology in Pasadena.

“We are seeing a lot of variation, which may be a result of clumps or warped structures in the planet-forming [clouds].”

The new image was taken after Spitzer ran out of its coolant in May 2009, beginning its extended “warm” mission. The coolant was needed to chill the instruments, but the two shortest-wavelength infrared channels still work normally at the new, warmer temperature of –243 Celsius.

In this new phase of the mission, Spitzer is able to spend more time on projects that cover a lot of sky and require longer observation times.

One such project is the “Young Stellar Object Variability” programme, in which Spitzer looks repeatedly at the same patch of the Orion nebula, monitoring the same set of about 1,500 variable stars over time. It has already taken about 80 pictures of the region over 40 days. A second set of observations will be made in late 2010.

The region’s twinkling stars are about one million years old. This might invoke thoughts of wrinkle cream to a movie star, but in the cosmos, it is quite young. Our middle-aged Sun is 4.6 billion years old.

The hottest stars in the region, called the Trapezium cluster, are bright spots at centre right in the image. Radiation and winds from those stars has sculpted and blown away surrounding dust. The densest parts of the cloud appear dark at centre left.

Adapted from information issued by NASA / JPL-Caltech.

Dusty nebula hides a super-hot star

The Gum 19 nebula

The Gum 19 nebula glows under influence of a 30,000° Celsius star.

The little-known Gum 19 nebula seems to have a dual nature.

On one side, hydrogen gas is lit up by a supergiant blue star called V391 Velorum. On the other, new stars are being formed within a ribbon of luminous and dark material.

Gum 19 is located approximately 22,000 light years away in the direction of the constellation Vela (the Sail). The name comes from a 1955 catalogue produced by Australian astrophysicist Colin S. Gum, who made the first significant survey of so-called HII (“H-two”) regions in the southern sky.

HII refers to hydrogen gas that is ionised, or energised to the extent that the hydrogen atoms lose their electrons. Such regions emit light at well-defined wavelengths (or colours), thereby giving these clouds their characteristic glow.

This new image of Gum 19 was captured by an infrared instrument called SOFI, mounted on the European Southern Observatory’s (ESO) New Technology Telescope (NTT) that operates at the La Silla Observatory in Chile. Observing the nebula at infrared wavelengths allows astronomers to “see through” at least some of the dust.

Fuelling Gum 19’s glow is the gigantic, super-hot star V391 Velorum, which boasts a surface temperature of around 30,000 degrees Celsius. This massive star has a temperamental nature, however, and is categorized as a “variable star” – its brightness can fluctuate suddenly as a result of activity such as ejections of shells of gas.

Stars like V391 Velorum don’t burn brightly for long, and after a relatively short lifetime of about ten million years blow up as supernovae. These explosions blast heated matter into surrounding space, an event that can radically change the colour and shape of the enclosing nebula. When this happens to V391, the Gum 19 nebula will change dramatically.

Within Gum 19, new stars continue to grow. HII regions are sites where huge quantities of gas and dust have begun to collapse under their own gravity. In several million years — a blink of an eye in cosmic time — these shrinking knots of matter will eventually reach the high density at their centres necessary to ignite nuclear fusion…new stars.

An island of stars in the making

The NGC 1788 nebula

The NGC 1788 nebula, where stars are being born

The delicate nebula NGC 1788, located in a dark and often neglected corner of the constellation Orion, is revealed in a new and finely nuanced image released by the European Space Agency (ESO).

Although this ghostly cloud is rather isolated from Orion’s bright stars, the latter’s powerful winds and light have had a strong impact on the nebula, forging its shape and making it home to a multitude of infant suns.

Stargazers all over the world are familiar with the distinctive profile of the constellation of Orion (the Hunter). Fewer know about the nebula NGC 1788, a subtle, hidden treasure just a few degrees away from the bright stars in Orion’s belt.

NGC 1788 is a reflection nebula, whose gas and dust scatter the light coming from a small cluster of young stars in such a way that the tenuous glow forms a shape reminiscent of a gigantic bat spreading its wings.

Very few of the stars belonging to the nebula are visible in this image, as most of them are obscured by the dusty cocoons surrounding them. The most prominent, named HD 293815, can be distinguished as the bright star in the upper part of the cloud, just above the centre of the image and the pronounced dark lane of dust extending through the nebula.

Birthplace of stars

Although NGC 1788 appears at first glance to be an isolated cloud, observations covering a field beyond the one presented in this image have revealed that bright, massive stars, belonging to the vast stellar groupings in Orion, have played a decisive role in shaping NGC 1788 and stimulating the formation of its stars. They are also responsible for setting the hydrogen gas ablaze in the parts of the nebula facing Orion, leading to the red, almost vertical rim visible in the left half of the image.

Part of the NGC 1788 nebula

The red glow is hydrogen gas being heated by the light of nearby stars.

All the stars in this region are extremely young, with an average age of only a million years, a blink of an eye compared to the Sun’s age of 4.5 billion years.

Analysing them in detail, astronomers have discovered that these “preschool” stars fall naturally into three well separated classes: the slightly older ones, located on the left side of the red rim, the fairly young ones, to its right, making up the small cluster enclosed in the nebula and illuminating it, and eventually the very youngest stars, still deeply embedded in their nascent dusty cocoons, further to the right.

Although none of the youngest stars are visible in this image because of the obscuring dust, dozens of them have been revealed through observations at infrared and millimetre wavelengths of light.

This fine distribution of stars, with the older ones closer to Orion and the younger ones concentrated on the opposite side, suggests that a wave of star formation, generated around the hot and massive stars in Orion, propagated throughout NGC 1788 and beyond.

This image was obtained using the Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile.

Adapted from information issued by ESO.