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Gallery: A fluffy galaxy

Galaxy NGC 3521

Galaxy NGC 3521 is relatively nearby, at a distance of only 35 million light-years. It's patchy spiral arms give it a fluffy look.

IT’S 35 MILLION LIGHT-YEARS AWAY and 50,000 light-years wide. It’s the spiral galaxy NGC 3521, a spectacular object with a bright and compact core or nucleus, surrounded by richly detailed spiral structure.

This new picture from the European Southern Observatory’s (ESO) Very Large Telescope shows that the most distinctive features of NGC 3521 are its long spiral arms, which are dotted with star-forming regions and interspersed with veins of dust.

The arms are rather irregular and patchy, making NGC 3521 a typical example of a ‘flocculent spiral galaxy’.

These types of galaxies have ‘fluffy’ spiral arms that contrast with the sweeping arms of ‘grand-design spirals’ such as the famous Whirlpool galaxy or M 51, discovered by Charles Messier.

NGC 3521 is bright and relatively close-by, and can easily be seen with a small telescope such as the one used by Messier to catalogue a series of hazy astronomical objects when he was searching for comets in the 1700s.

Strangely, the French astronomer seems to have missed this spiral even though he identified several other galaxies of similar brightness in the constellation of Leo.

It was only in the year that Messier published the final version of his catalogue, 1784, that another famous astronomer, William Herschel, discovered NGC 3521 early on in his more detailed surveys of the northern skies.

Through his larger, 47cm aperture, telescope, Herschel saw a “bright centre surrounded by nebulosity,” according to his observation notes.

In this new VLT picture, colourful, yet ill-defined spiral arms replace Herschel’s “nebulosity”. Older stars dominate the reddish area in the centre while young, hot blue stars permeate the arms further away from the core.

Download wallpapers of the spiral galaxy NGC 3521:

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Adapted from information issued by ESO / O. Maliy.

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Was the universe born spinning?

Galaxy Messier 101

Researchers have found an excess of counter-clockwise rotating, or 'left-handed,' spiral galaxies like the one pictured (known as Messier 101) compared to their 'right-handed' counterparts. This provides evidence that the universe does not have mirror symmetry, and that it may have been born spinning at the time of the Big Bang.

  • Universe long thought to have ‘mirror symmetry’
  • Symmetry could be wrong if more galaxies spin in one direction
  • Early results show more galaxies rotate ‘left’ than ‘right’

PHYSICISTS AND ASTRONOMERS have long thought that the universe has mirror symmetry, like a basketball, but recent findings from the University of Michigan dispute this.

The findings suggest that the shape of the Big Bang might be more complicated than previously thought, and that the early universe spun about an axis.

To test for the assumed mirror symmetry, physics professor Michael Longo and a team of five undergraduates catalogued the rotation direction of tens of thousands of spiral galaxies photographed in the Sloan Digital Sky Survey.

The mirror image of a counter-clockwise rotating galaxy would have clockwise rotation. More of one type than the other would be evidence for a breakdown of symmetry, or, in physics speak, a ‘parity violation’ on cosmic scales, Longo said.

One in a million

The researchers found evidence that galaxies tend to rotate in a preferred direction.

They uncovered an excess of left-handed, or counter-clockwise rotating, spirals in the part of the sky toward the north pole of the Milky Way. The effect extended beyond 600 million light-years away.

“The excess is small, about 7 percent, but the chance that it could be a cosmic accident is something like one in a million,” Longo said.

Spiral galaxy NGC 4622

Spiral galaxy NGC 4622

“These results are extremely important because they appear to contradict the almost universally accepted notion that on sufficiently large scales the universe is isotropic, with no special direction.”

Spin cycle

The work provides new insights about the shape of the Big Bang. A symmetric and isotropic universe would have begun with a spherically symmetric explosion shaped like a basketball.

If the universe was born rotating, like a spinning basketball, Longo said, it would have a preferred axis, and galaxies would have retained that initial motion.

Is the universe still spinning?

“It could be,” Longo said. “I think this result suggests that it is.”

Because the Sloan telescope is in New Mexico, the data the researchers analysed for their recent paper came mostly from the northern regions of the sky. An important test of the findings will be to see if there is an excess of right-handed spiral galaxies in the southern hemisphere. This research is currently under way.

Adapted from information issued by the University of Michigan. Messier 101 image courtesy NASA, ESA, K. Kuntz (Johns Hopkins University), F. Bresolin (University of Hawaii), J. Trauger (Jet Propulsion Lab), J. Mould (National Optical Astronomy Observatory), Y.-H. Chu (University of Illinois, Urbana), and the Space Telescope Science Institute. NGC 4622 image courtesy NASA and The Hubble Heritage Team (STScI/AURA); acknowledgment: Dr. Ron Buta (U. Alabama), Dr. Gene Byrd (U. Alabama) and Tarsh Freeman (Bevill State Community College).

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Are galaxies ‘see through’?

Galaxy pair AM500-620

Galaxy pair AM500-620 comprises two dusty spiral galaxies, one in front of the other.

THIS HUBBLE SPACE TELESCOPE image shows a galaxy pair known only by its catalogue number, AM0500-620. It comprises consists of a highly symmetrical spiral galaxy seen nearly face-on, partially backlit by a background galaxy.

The Hubble image shows the foreground spiral galaxy to have a number of ‘dust lanes’ between its spiral arms.

The background galaxy had originally been classified as an elliptical galaxy, but Hubble’s observations revealed it to be a dusty spiral arms and bright knots of stars.

The image was taken in order to work out how much dust is held within galaxies, and whether this dust reduces the amount of light we see from the stars within those galaxies.

By finding foreground-background galaxy pairs, astronomers were able to refine their estimates of dust in the foreground galaxies through the backlighting effect of the background galaxies.

AM0500-620 is 350 million light-years away from Earth in the direction of the constellation Dorado, the Swordfish.

Download a 1280 x 1280-pixel wallpaper image of AM0500-620.

Adapted from information issued by NASA, ESA, the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration and W. Keel (University of Alabama, Tuscaloosa) / UA News Bureau.

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Dusty galaxy shows off its spirals

Hubble image of NGC 2841

NASA's Hubble Space Telescope reveals a majestic disc of stars and dust lanes in this view of the spiral galaxy NGC 2841, which lies 46 million light-years away. See below for links to large-size wallpaper images for your computer screen.

NASA’S HUBBLE SPACE TELESCOPE has revealed a majestic disc of stars and dust lanes in a new view of the spiral galaxy NGC 2841.

A bright cusp of starlight marks the galaxy’s centre. Spiralling outward are dust lanes that are silhouetted against the population of whitish middle-aged stars. Much younger blue stars trace the spiral arms.

Notably missing are pinkish emission nebulae indicative of new star birth. It is likely that the radiation and supersonic winds from fiery, super-hot, young blue stars cleared out the remaining gas (which glows pink), and hence shut down further star formation in the regions in which they were born.

NGC 2841currently has a relatively low star formation rate compared to other spirals that are ablaze with emission nebulae.

NGC 2841 lies 46 million light-years away in direction of the constellation of Ursa Major (The Great Bear). This image was taken in 2010 through four different filters on Hubble’s Wide Field Camera 3. Wavelengths range from ultraviolet light through visible light to near-infrared light.

Screen wallpapers:

Galaxy NGC 2841 wallpaper 1024 x 768

Galaxy NGC 2841 wallpaper 1280 x 1024

Galaxy NGC 2841 wallpaper 1600 x 1200

Adapted from information issued by HEIC. 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.

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Spiral galaxies stripped bare

Spiral galaxies

Six spectacular spiral galaxies are seen in new infrared pictures from ESO’s Very Large Telescope (VLT) at the Paranal Observatory in Chile. From left to right the galaxies are NGC 5427, Messier 100 (NGC 4321), NGC 1300, NGC 4030, NGC 2997 and NGC 1232.

Six spectacular spiral galaxies are seen in a clear new light in images from the European Southern Observatory’s (ESO) Very Large Telescope (VLT) at the Paranal Observatory in Chile.

The pictures were taken in infrared light, using the impressive power of the HAWK-I (High-Acuity Wide-field K-band Imager) camera, and will help astronomers understand how the remarkable spiral patterns in galaxies form and evolve.

HAWK-I is one of the newest and most powerful cameras on ESO’s Very Large Telescope (VLT). It is sensitive to infrared light, which means that much of the obscuring dust in the galaxies’ spiral arms becomes transparent to its detectors.

Compared to the earlier, and still much-used, VLT infrared camera ISAAC, HAWK-I has sixteen times as many pixels to cover a much larger area of sky in one shot and, by using newer technology than ISAAC, it has a greater sensitivity to faint infrared radiation.

Because HAWK-I can study galaxies stripped bare of the confusing effects of dust and glowing gas, it is ideal for studying the vast numbers of stars that make up spiral arms.

The six galaxies are part of a study of spiral structure led by Preben Grosbøl at ESO. The image were acquired to help understand the complex and subtle ways in which the stars in these systems form into such perfect spiral patterns.

The first image shows NGC 5247, a spiral galaxy dominated by two huge arms, located 60-70 million light-years away. The galaxy lies face-on towards Earth, thus providing an excellent view of its pinwheel structure.

NGC 5247

NGC 5247, a grand design barred spiral galaxy, located 60-70 million light-years from Earth.

The galaxy in the second image is Messier 100, also known as NGC 4321, which was discovered in the 18th century. It is a fine example of a “grand design” spiral galaxy—a class of galaxies with very prominent and well-defined spiral arms. About 55 million light-years from Earth, Messier 100 is part of the Virgo Cluster of galaxies.

Messier 100

Messier 100, also known as NGC 4321, was discovered in the 18th century. It is about 55 million light-years from Earth.

The third image is of NGC 1300, a spiral galaxy with arms extending from the ends of a spectacularly prominent central bar. It is considered a prototypical example of barred spiral galaxies and lies at a distance of about 65 million light-years.

NGC 1300

NGC 1300, a spiral galaxy with arms extending from the ends of a spectacularly prominent elongated central region, or "bar". It is about 65 million light-years from Earth.

The spiral galaxy in the fourth image, NGC 4030, lies about 75 million light-years from Earth. In 2007 Takao Doi, a Japanese astronaut who doubles as an amateur astronomer, spotted a supernova—a stellar explosion that is briefly almost as bright as its host galaxy—going off in this galaxy.

NGC 4030

NGC 4030 is about 75 million light-years from Earth.

The fifth image, NGC 2997, is a spiral galaxy roughly 30 million light-years away. NGC 2997 is the brightest member of a group of galaxies of the same name in the Local Supercluster of galaxies. Our own Local Group, of which the Milky Way is a member, is itself also part of the Local Supercluster.

NGC 2997

NGC 2997, a spiral galaxy roughly 30 million light-years from Earth, is the brightest member of a group of galaxies in the Local Supercluster of galaxies.

Last but not least, NGC 1232 is a beautiful galaxy some 65 million light-years away. The galaxy is classified as an intermediate spiral galaxy—somewhere between a barred and an unbarred spiral galaxy. An image of this galaxy and its small companion galaxy NGC 1232A in visible light was one of the first produced by the VLT. HAWK-I has now returned to NGC 1232 to show a different view of it at near-infrared wavelengths.

NGC 1232

NGC 1232 is a spiral galaxy some 65 million light-years away. It is classified as an intermediate spiral galaxy—somewhere between a barred and an unbarred spiral galaxy.

As this galactic gallery makes clear, HAWK-I lets us see the spiral structures in these six bright galaxies in exquisite detail and with a clarity that is only made possible by observing in the infrared.

Adapted from information issued by ESO / P. Grosbøl.

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Hubble sees a mini-Milky Way

Galaxy NGC 3982

Hubble Space Telescope image of galaxy NGC 3892. It is 30,000 light-years wide and 68 million light-years from Earth.

Though the universe is chock full of spiral-shaped galaxies, no two look exactly the same.

This face-on spiral galaxy, called NGC 3982, is striking for its rich tapestry of star birth, along with its winding arms. It’s like a smaller version of our Milky Way.

The arms are lined with pink star-forming regions of glowing hydrogen, newborn blue star clusters, and obscuring dust lanes that provide the raw material for future generations of stars.

The bright nucleus is home to an older population of stars, which grow ever more densely packed toward the centre.

NGC 3982 is located about 68 million light-years away in the direction of the constellation Ursa Major. The galaxy spans about 30,000 light-years, one-third of the size of our Milky Way galaxy.

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

This colour image is composed of exposures taken by the Hubble Space Telescope’s Wide Field Planetary Camera 2 (WFPC2), the Advanced Camera for Surveys (ACS), and the Wide Field Camera 3 (WFC3). The observations were taken between March 2000 and August 2009.

The rich colour range comes from the fact that the galaxy was photographed in visible and near-infrared light. Also used was a filter that isolates hydrogen emission that emanates from bright star-forming regions dotting the spiral arms.

Adapted from information issued by NASA / ESA / HHT (STScI/AURA) / A. Riess (STScI).

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Spiral galaxy seen in a new light

Infrared view of NGC 1365

An infrared view of NGC 1365, a beautiful barred spiral galaxy in the Fornax cluster of galaxies, about 60 million light-years from Earth.

  • Galaxy NGC 1365, the Great Barred Spiral Galaxy
  • 200,000 light-years wide, with two huge spiral arms
  • Located 60 million light-years from Earth

A new image taken with the powerful HAWK-I camera on the European Southern Observatory’s (ESO’s) Very Large Telescope in Chile shows the beautiful “barred spiral” galaxy NGC 1365 in infrared light.

NGC 1365 is a member of the Fornax cluster of galaxies, about 60 million light-years from Earth.

NGC 1365 is one of the best-known and most-studied barred spiral galaxies, sometimes nicknamed the Great Barred Spiral Galaxy because of its strikingly perfect form…a straight “bar” or middle section and two prominent outer spiral arms.

Closer to the centre there is also a second spiral structure, and the galaxy as a whole is laced with delicate lanes of interstellar dust.

Astronomers consider it an excellent “laboratory” for studying how spiral galaxies form and evolve.

The new infrared images from HAWK-I are less affected by the dust that obscures parts of the galaxy than images taken at visible light wavelengths, and they reveal very clearly the glow from vast numbers of stars in both the bar and the spiral arms.

The images were acquired to help astronomers understand the complex flow of gas within the galaxy and how it affects the reservoirs of gas from which new stars can form.

The huge bar disturbs the shape of the gravitational field of the galaxy and this leads to regions where gas becomes compressed, triggering the formation of new stars.

See the full-size, high-resolution version of the image (suitable for PC wallpaper) here.

Visible light and infrared views of NGC 1365

This comparison shows a visible-light image (left) of NGC 1365 along with the new infrared view (right). The infrared view "peels away" the veil of dust to reveal more stars beneath.

Black hole hidden in the core

Many huge young star clusters are visible in the main spiral arms, each containing hundreds or thousands of bright young stars that are less than 10 million years old.

The galaxy is too remote for single stars to be seen—most of the tiny clumps visible in the picture are really clusters of stars.

While the bar of the galaxy comprises mainly older stars long past their prime, many new stars are born in stellar “nurseries” of gas and dust in the inner spiral close to the core. Over the whole galaxy, stars are forming at a rate of about three times the mass of our Sun per year.

The bar also funnels gas and dust gravitationally into the very centre of the galaxy, where astronomers have found evidence for the presence of a super-massive black hole, well hidden among myriads of intensely bright new stars.

Here’s a video that zooms in on NGC 1365, alternating between visible wavelength and infrared wavelength views:

NGC 1365, including its two huge outer spiral arms, is around 200,000 light-years across. Different parts of the galaxy take different times to make a full rotation around the core, with the outer parts of the bar taking about 350 million years to complete one circuit.

NGC 1365 and other galaxies of its type have come to more prominence in recent years with new observations indicating that our Milky Way galaxy could also be of the barred spiral type.

Such galaxies are quite common—two thirds of spiral galaxies are barred according to recent estimates. Studying them can help astronomers understand our own galactic home.

Adapted from information issued by ESO / P. Grosbøl.

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Spiral galaxy M83

Image of the nearby galaxy Messier 83

This image of the nearby galaxy Messier 83 was taken in the infrared part of the spectrum with the HAWK-I instrument on ESO’s Very Large Telescope, revealing vast numbers of stars within the galaxy.

  • 15 million light-years away
  • 40 percent the size of the Milky Way
  • Home to 6 recently spotted exploding stars

The European Southern Observatory (ESO) has released a beautiful image of the nearby galaxy Messier 83 taken by the HAWK-I instrument on ESO’s Very Large Telescope (VLT) at the Paranal Observatory in Chile.

The picture shows the galaxy in infrared light and demonstrates the impressive power of the camera to create one of the sharpest and most detailed pictures of Messier 83 ever taken from the ground.

Messier 83 is about 15 million light-years away. It is over 40,000 light-years wide, only 40 percent the size of the Milky Way, but in many ways is quite similar to our home galaxy, both in its spiral shape and the presence of a bar of stars across its centre.

The galaxy is famous among astronomers for its many supernovae: vast explosions that end the lives of some stars. Over the last century, six supernovae have been spotted in Messier 83 — a record number that is matched by only one other galaxy.

Comparison of the view of the galaxy Messier 83 in infrared and visible light.

Comparison of the view of the galaxy Messier 83 at infrared light wavelengths (left) and at visible light wavelengths (right). In the infrared, the dust that obscures many stars becomes nearly transparent, making the spiral arms seem less dramatic, but revealing a whole host of new stars that are otherwise invisible.

Even without supernovae, Messier 83 is one of the brightest nearby galaxies, visible using just binoculars.

When viewed in infrared light by HAWK-I, most of the obscuring dust that hides much of Messier 83 becomes transparent. The brightly lit gas around hot young stars in the spiral arms is also less prominent in infrared pictures. As a result much more of the structure of the galaxy and the vast hordes of its constituent stars can be seen.

This clear view is important for astronomers looking for clusters of young stars, especially those hidden in dusty regions of the galaxy. Studying such star clusters was one of the main scientific goals of these observations. The acute vision of HAWK-I reveals far more stars within the galaxy.

Adapted from information issued by ESO / M. Gieles / Mischa Schirmer.