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GALLERY: Orion’s fiery sword

WISE image of the Orion Nebula

The Orion Nebula – seen here at infrared wavelengths in a WISE space observatory image – is a dusty, turbulent region where stars are being born.

THE TANGLE OF CLOUDS and stars that lie in Orion’s sword is showcased in a new, expansive view from NASA’s Wide-field Infrared Survey Explorer, or WISE, spacecraft.

The constellation Orion, named for a mythical hunter, is visible in evening skies throughout the world from about December through April. The constellation appears tranquil and still to the naked eye, but in the hunter’s ‘sword’, what at first appears to be a slightly fuzzy star is actually a turbulent cauldron of stellar birth – the Orion Nebula.

WISE captured this vast view of the nebula in infrared light, picking up the glow from interstellar dust heated by newborn stars. The colours green and red in this false-colour view, highlight the warmed dust, while the white regions are even hotter. The energy from massive stars has ‘burned’ through the dust, carving out cavities, the largest of which is seen at the centre of the picture.

Astronomers think that our Sun was probably born in a similar cloud some five billion years ago. Over time, the cloud would have dispersed and the stars would have drifted apart, leaving us more isolated in space. The crowded newborn stars in the Orion nebula are less than 10 million years old – billions of years from now, they will likely spread out.

Adapted from information issued by NASA/JPL-Caltech/UCLA.

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From darkness comes the light

Lupus 3 dark cloud

The Lupus 3 dark cloud, about 600 light-years from Earth, is a region where new stars are forming. Alongside is a cluster of brilliant stars that have already emerged from their dusty stellar nursery.

  • Lupus 3 stellar nursery is about 600 light-years from Earth
  • New stars are forming out of the dark dust clouds

A NEW IMAGE RELEASED by the European Southern Observatory shows a dark cloud where new stars are forming, along with a cluster of brilliant stars that have already emerged from their dusty stellar nursery.

The new picture was taken with the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile and is the best image ever taken at visible light wavelengths of this little-known object.

The cloud is known as Lupus 3, and it lies about 600 light-years from Earth. The section shown here is about five light-years across.

On the left of this new image there is a dark cloud that contains huge amounts of cool cosmic dust and is a nursery where new stars are being born. It is likely that the Sun formed in a similar star formation region more than four billion years ago.

As the denser parts of such clouds contract under the effects of gravity they heat up and start to shine – they’re new stars. At first their light is blocked by the dusty clouds and can be seen only by telescopes observing at longer wavelengths than visible light, such as infrared. But as the stars get hotter and brighter, their intense radiation and stellar winds gradually clear the clouds around them until they emerge in all their glory.

The bright stars on the right are a perfect example. Some of their brilliant blue light is being scattered off the remaining dust around them. The two brightest stars can be seen easily with a small telescope or binoculars. They are young stars that have not yet started to shine by nuclear fusion in their cores and are still surrounded by glowing gas. They’re probably less than one million years old.

Wider view of Lupus 3

A wider view of Lupus 3 shows the extent of the dark dust cloud, silhouetted against the starry background of our galaxy.

Adapted from information issued by ESO. Images courtesy ESO / F. Comeron / Digitised Sky Survey 2 / Davide De Martin.

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Hubble spots a hidden treasure

Josh Lake's image of LHA 120-N11

Josh Lake’s image of LHA 120-N11, which comprises several adjacent pockets of gas and star formation. It is located in the Large Magellanic Cloud galaxy, roughly 200,000 light-years from Earth.

NEARLY 200,000 LIGHT-YEARS from Earth, the Large Magellanic Cloud, a satellite galaxy of the Milky Way, floats in space, in a long and slow dance around our galaxy.

Vast clouds of gas within it slowly collapse to form new stars. In turn, these light up the gas clouds in a riot of colours, visible in this image from the NASA/ESA Hubble Space Telescope.

The Large Magellanic Cloud (LMC) is ablaze with star-forming regions. From the Tarantula Nebula, the brightest stellar nursery in our cosmic neighbourhood, to LHA 120-N 11, part of which is featured in this Hubble image, the small and irregular galaxy is scattered with glowing nebulae, the most noticeable sign that new stars are being born.

The LMC is in an ideal position for astronomers to study the phenomena surrounding star formation. It lies in a fortuitous location in the sky, far enough from the plane of the Milky Way that it is neither outshone by too many nearby stars, nor obscured by the dust in the Milky Way’s centre.

It is also close enough to study in detail (less than a tenth of the distance of the Andromeda Galaxy, the closest spiral galaxy), and lies almost face-on to us, giving us a bird’s eye view.

Smokey remains of dead stars

LHA 120-N 11 (known as N11 for short) is a particularly bright region of the LMC, consisting of several adjacent pockets of gas and star formation. NGC 1769 (in the centre of this image) and NGC 1763 (to the right) are among the brightest parts.

In the centre of this image, a dark finger of dust blots out much of the light. While nebulae are mostly made of hydrogen, the simplest and most plentiful element in the universe, dust clouds are home to heavier and more complex elements, which go on to form rocky planets like the Earth.

Much finer than household dust (it is more like smoke), this interstellar dust consists of material expelled from previous generations of stars as they died.

The data in this image were identified by Josh Lake, an astronomy teacher at Pomfret School in Connecticut, USA, in the Hubble’s Hidden Treasures image processing competition. The competition invited members of the public to dig out unreleased scientific data from Hubble’s vast archive, and to process them into stunning images.

Josh Lake won first prize in the competition with an image (below) contrasting the light from glowing hydrogen and nitrogen in N 11. The image at the top of the page combines the data he identified with additional exposures taken in blue, green and near infrared light.

Josh Lake's image of NGC 1763

Josh Lake’s image of the NGC 1763 region of nebulosity and stars in the Large Magellanic Cloud galaxy. The image won him first prize in Hubble’s Hidden Treasures Image Processing Competition

More information: Hidden Treasures

Adapted from information issued by ESA / Hubble Information Centre. Images: NASA, ESA and J. Lake.

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Tiny galaxy with a bright nebula

Dwarf galaxy NGC 2366

The dwarf galaxy NGC 2366 might be small and dim, but it is home to a surprisingly bright, star-forming nebula—the blue patch in the top-right corner—and close enough so that its individual stars can be made out.

THE STARRY SMOG stretching across this image obtained by the Hubble Space Telescope is the central part of the dwarf galaxy known as NGC 2366. The most obvious feature in this galaxy is a large nebula visible in the upper-right part of the image, an object known as NGC 2363.

A nearby yellowish swirl is not in fact part of the nebula. It is a spiral galaxy much further away, whose light is shining right through NGC 2366. This is possible because galaxies are not solid objects. Galaxies are overwhelmingly made up of the empty space between stars.

NGC 2366 and NGC 2363 are located about 10 million light-years away. As a dwarf galaxy, NGC 2366’s size is in the same ballpark as the two main satellite galaxies of our Milky Way, named the Large and Small Magellanic Clouds. Like the Magellanic Clouds, NGC 2366’s lack of well-defined structure leads astronomers to further classify it as an irregular galaxy.

Although NGC 2366 might be small by the standards of galaxies, many of its stars are not, and the galaxy is home to numerous gigantic blue stars. The blue dots scattered throughout the galaxy speak to the burst of star formation that the galaxy has undergone in recent cosmic time. A new generation of these stellar titans has lit up the nebula NGC 2363.

In gas-rich star-forming regions, the ultraviolet radiation from young, big, blue stars excites the hydrogen gas, making it glow. NGC 2363, as well as other, smaller patches seen throughout Hubble’s image, are the latest birth sites for stellar giants.

Imaged through green and infrared filters, these nebulae take on a blue-ish tinge in this image, though their actual colour is a shade of red.

Adapted from information issued by NASA / ESA.

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Galaxy caught blowing bubbles

Hubble Space Telescope image of Holmberg II

The Hubble Space Telescope captured this image of dwarf irregular galaxy Holmberg II. The main part of the galaxy is the spread of stars in the lower left half of the image. Huge bubbles of glowing gas produced by stellar explosions dominate the galaxy; they are now sites of ongoing star formation.

HUBBLE’S FAMOUS IMAGES OF GALAXIES typically show them to be elegant spirals or soft-edged elliptical shapes.

But these neat forms are only representative of large galaxies. Smaller galaxies like the dwarf irregular galaxy Holmberg II come in many shapes and types that are harder to classify.

Holmberg II’s indistinct shape is punctuated by huge glowing bubbles of gas, captured in this image from the Hubble Space Telescope.

The intricate glowing shells of gas were formed by the energetic life cycles of many generations of stars. High-mass stars form in dense regions of gas, and later in life expel strong stellar winds that blow away the surrounding material.

At the very end of their lives, they explode in as a supernova. Shock waves rip through these less dense regions blowing out and heating the gas, forming the delicate shells we see today.

Holmberg II is a patchwork of dense star-forming regionsand extensive barren areas with less material, which can stretch across thousands of light-years.

Keck Observatory view of Holmberg II

A wider view of Holmberg II. Courtesy B. Mendez / Keck Observatory.

As a dwarf galaxy, it has neither the spiral arms typical of galaxies like the Milky Way nor the dense nucleus of an elliptical galaxy.

This makes Holmberg II, gravitationally speaking, a gentle haven where fragile structures such as these bubbles can hold their shape.

A hidden black hole?

While the galaxy is unremarkable in size, Holmberg II does have some intriguing features. As well as its unusual appearance—which earned it a place in Halton Arp’s Atlas of Peculiar Galaxies, a treasure trove of weird and wonderful objects—the galaxy hosts an ultraluminous X-ray source in the middle of the three gas bubbles in the top right of the image.

There are competing ideas as to what causes this powerful radiation—one intriguing possibility is that an intermediate-mass black hole is pulling in material from its surroundings, with the material giving off energy as it nears the black hole.

The colourful image is a composite of visible and near-infrared exposures taken using the Wide Field Channel of Hubble’s Advanced Camera for Surveys. Hubble is a project of international cooperation between the European Space Agency and NASA.

Download the Hubble wallpapers:

Holmberg II (1024×768, 588.2 KB)

Holmberg II (1280×1024, 1.0 MB)

Holmberg II (1600×1200, 1.5 MB)

Holmberg II (1920×1200, 1.8 MB)

Adapted from information issued by HEIC / NASA / ESA.

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A nebula to dye for!

The Rho Ophiuchi clouds

The colourful Rho Ophiuchi star formation region, about 400 light-years from Earth, contains very cold (around -250 degrees Celsius), dense clouds of cosmic gas and dust, in which new stars are being born. Astronomers using the APEX telescope have detected hydrogen peroxide molecules in the area marked with the red circle.

MOLECULES OF HYDROGEN PEROXIDE have been found for the first time in interstellar space. The discovery gives clues about the chemical link between two molecules critical for life: water and oxygen.

On Earth, hydrogen peroxide plays a key role in the chemistry of water and ozone in our planet’s atmosphere, and is familiar for its use as a disinfectant or to bleach hair blonde. It’s also sometimes used as rocket fuel!

An international team of astronomers made the discovery with the Atacama Pathfinder Experiment telescope (APEX), situated on the 5,000-metre-high Chajnantor plateau in the Chilean Andes.

They studied a region in our galaxy close to the star Rho Ophiuchi, about 400 light-years away. The region contains very cold (around -250 degrees Celsius), dense clouds of cosmic gas and dust, in which new stars are being born.

The clouds are mostly made of hydrogen, but contain traces of other chemicals, and are prime targets for astronomers hunting for molecules in space.

Telescopes such as APEX, which make observations of light at millimetre- and submillimetre-wavelengths, are ideal for detecting the signals from these molecules.

Now, the team has found the characteristic signature of light emitted by hydrogen peroxide, coming from part of the Rho Ophiuchi clouds.

“We were really excited to discover the signatures of hydrogen peroxide with APEX,” says Per Bergman, astronomer at Onsala Space Observatory in Sweden. “We knew from laboratory experiments which wavelengths to look for, but the amount of hydrogen peroxide in the cloud is just one molecule for every ten billion hydrogen molecules, so the detection required very careful observations.”

Bergman is lead author of the study, which is published in the journal Astronomy & Astrophysics.

APEX telescope

The APEX telescope studies the cosmos at millimetre- and submillimetre-wavelengths—ideal for detecting certain molecules.

Clue to the origin of water

Hydrogen peroxide (H2O2) is a key molecule for both astronomers and chemists. Its formation is closely linked to two other familiar molecules, oxygen and water, which are critical for life. Because much of the water on our planet is thought to have originated in space, scientists are keen to understand how it is formed.

Hydrogen peroxide is thought to form in space on the surfaces of cosmic dust grains—very fine particles similar to sand and soot—when hydrogen (H) is added to oxygen molecules (O2). A further reaction of the hydrogen peroxide with more hydrogen is one way to produce water (H2O).

This new detection of hydrogen peroxide will therefore help astronomers better understand the formation of water in the Universe.

“We don’t understand yet how some of the most important molecules here on Earth are made in space. But our discovery of hydrogen peroxide with APEX seems to be showing us that cosmic dust is the missing ingredient in the process,” says Bérengère Parise, head of the Emmy Noether research group on star formation and astrochemistry at the Max-Planck Institute for Radio Astronomy in Germany, and a co-author of the paper.

To work out just how the origins of these important molecules are intertwined will need more observations of Rho Ophiuchi and other star-forming clouds with future telescopes such as the Atacama Large Millimeter/submillimeter Array (ALMA)—and help from chemists in laboratories on Earth.

The new discovery may also help astronomers understand another interstellar mystery—why oxygen molecules are so hard to find in space. It was only in 2007 that oxygen molecules were first discovered in space, by the satellite Odin.

APEX is a collaboration between the Max-Planck Institute for Radio Astronomy (MPIfR), the Onsala Space Observatory (OSO) and European Southern Observatory. The telescope is operated by ESO.

Wide field view of the Rho Ophiuchi star formation

A full view of the Rho Ophiuchi star formation region, which is a favourite of amateur astronomers. Rho Ophiuchi itself is the bright star near the top of the image. The bright yellowish star in the bottom left is Antares, one of the brightest stars in the sky. Below and to Antares’ right is the globular star cluster Messier 4.

Download wallpapers of the Rho Ophiuchi clouds:

1024 x 768 (475.0 KB)

1280 x 1024 (833.5 KB)

1600 x 1200 (1.2 MB)

1920 x 1200 (1.3 MB)

Adapted from information issued by ESO / S. Guisard (www.eso.org/~sguisard) / H.H.Heyer.

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Meet the Meathook Galaxy

The Meathook Galaxy

This wide view of the Meathook Galaxy shows its bent spiral arms, and glowing pink regions of hydrogen gas where lots of stars have recently formed.

THE MEATHOOK GALAXY, or NGC 2442, has a dramatically lopsided shape. One spiral arm is tightly folded in on itself and played host to a recent supernova (exploding star), while the other, dotted with glowing regions of recent star formation, extends far out from the galaxy’s core or nucleus.

The galaxy’s distorted shape is thought to be the result of the gravitational pull of a passing galaxy at some point in the past, though astronomers so far have not been able to positively identify the culprit.

The broad view, taken by the Wide Field Imager on the MPG/ESO 2.2-metre telescope at La Silla, Chile, very clearly shows the double hook shape that gives the galaxy its nickname. It also captures several other galaxies close to NGC 2442 as well as many more remote galaxies in the background.

Hubble image of the Meathook Galaxy

A close-up Hubble view of the Meathook Galaxy shows its core as well as the more compact of its two spiral arms.

The close-up image from the NASA/ESA Hubble Space Telescope focuses on the galaxy’s nucleus and the more compact of its two spiral arms. In 1999, a massive star at the end of its life exploded in this arm…a phenomenon known as a supernova.

By comparing older ground-based observations, previous Hubble images made in 2001, and these shots taken in late 2006, astronomers have been able to study in detail what happened to the star in its dying moments. (By the time of this latest Hubble image, the supernova had faded and is not visible.)

Although the Wide Field Imager, being a ground-based instrument, cannot approach the sharpness of images from Hubble in space, it covers a much bigger section of sky in a single exposure. Combining ground- and space-based imagery often gives astronomers deeper insights.

The wide view also highlights the starting point of the life cycle of stars. Dotted across much of the galaxy, and particularly in the longer of the two spiral arms, are patches of pink and red. This colour comes from hydrogen gas in star-forming cloud regions—the powerful radiation of new-born stars ‘excites’ the gas in the clouds, making them glow a bright shade of red.

The near miss with the other galaxy is likely to have been the trigger for this recent burst of star formation. The same tidal forces that deformed the galaxy also disrupted the gas clouds and made them gravitationally collapse in on themselves, leading to the birth of new stars.

Download wallpapers of the Meathook Galaxy:

1024 x 768 (269.6kb)

1280 x 1024 (411.0kb)

1600 x 1200 (552.8kb)

Adapted from information issued by ESO. Images courtesy NASA/ESA and ESO.

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Incredible Hubble video

This Hubblecast features a spectacular new NASA/ESA Hubble Space Telescope image—one of the largest ever released of a star-forming region. It highlights N11, part of a complex network of gas clouds and star clusters within our neighbouring galaxy, the Large Magellanic Cloud. This region of energetic star formation is one of the most active in the nearby Universe.

Download an amazing screen wallpaper image of N11:

Adapted from information issued by NASA / ESA / Jesús Maíz Apellániz (Instituto de Astrofísica de Andalucía, Spain).

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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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New star-forming regions found

The Orion Nebula

The Orion Nebula, an example of an H II gas cloud, where hydrogen gas is ionised and glows.

  • Previously-unknown star forming regions found
  • Scattered through the Milky Way
  • Hold chemical clues to stellar evolution

Astronomers studying the Milky Way have discovered a large number of previously-unknown regions where massive stars are being formed. Their discovery provides important new information about the structure of our home Galaxy and promises to yield new clues about the chemical composition of the Galaxy.

“We can clearly relate the locations of these star-forming sites to the overall structure of the Galaxy,” said Thomas Bania, of Boston University.

“Further studies will allow us to better understand the process of star formation and to compare the chemical composition of such sites at widely different distances from the Galaxy’s centre.”

Bania worked with Loren Anderson of the Astrophysical Laboratory of Marseille in France, Dana Balser of the US National Radio Astronomy Observatory (NRAO), and Robert Rood of the University of Virginia.

Gas clouds hidden from view

Artist's impression of the Milky Way looking from above

Our current understanding of the major components of our galaxy, the Milky Way (artist's impression shown here). Astronomers have found dozens more star-forming regions known as H II clouds.

The star-forming regions the astronomers sought, called H II regions, are sites where hydrogen atoms are ionised, or stripped of their electrons, by the intense radiation of the massive, young stars. To find these regions hidden from visible-light detection by the Milky Way’s gas and dust, the researchers used infrared and radio telescopes.

“We found our targets by using the results of infrared surveys done with NASA’s Spitzer Space Telescope and of surveys done with the US National Science Foundation’s (NSF) Very Large Array (VLA) radio telescope,” Anderson said. “Objects that appear bright in both the Spitzer and VLA images we studied are good candidates for H II regions.”

The astronomers then used the NSF’s giant Robert C. Byrd Green Bank Telescope (GBT) in West Virginia, an extremely sensitive radio telescope. With the GBT, they were able to detect specific radio frequencies emitted by electrons as they recombined with protons to form hydrogen.

This evidence of recombination confirmed that the regions contained ionised hydrogen and thus are H II regions.

Our Galaxy’s chemical mix

Further analysis enabled the astronomers to determine the locations of the H II regions.  They found concentrations of the regions at the end of the Galaxy’s central elongated region and in its spiral arms. Their analysis also showed that 25 of the regions are farther from the Galaxy’s centre than the Sun.

“Finding the ones beyond the [Sun’s location] is important, because studying them will provide important information about the chemical evolution of the Galaxy,” Bania said. “There is evidence that the abundance of heavy elements changes with increasing distance from the Galactic centre.”

“We now have many more objects to study and improve our understanding of this effect.”

Adapted from information issued by NRAO / NASA / JPL-Caltech / R. Hurt (SSC-Caltech) / HHT (AURA / STScI / NASA).