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Hidden star groups uncovered

Star clusters discovered using VISTA

Using data from the VISTA infrared survey telescope, astronomers have discovered 96 new 'open' star clusters hidden behind dust in the Milky Way, 30 of which are shown in this mosaic.

  • Almost 100 star clusters found hiding behind dust in the Milky Way
  • Uncovered using the dust-penetrating power of infrared
  • There could be 30,000 more clusters still waiting to be found

NINETY-SIX PREVIOUSLY UNKNOWN ‘open star clusters’ have been found hiding behind dust in the Milky Way.

These tiny and faint groupings were invisible to previous surveys, but they could not escape the sensitive infrared detectors VISTA—an infrared survey telescope at the European Southern Observatory’s (ESO) Paranal Observatory in Chile—which can peer through the dust.

This result comes just one year after the start of the VISTA Variables in the Via Lactea programme (VVV), one of the six surveys running on the new telescope. (‘Via Lactea’ is the Latin name for the Milky Way.)

Invisible to most telescopes

Most stars that weigh more than half as much as our Sun form in groups, called open star clusters. These clusters are the building blocks of galaxies and vital for the formation and evolution of galaxies such as our own.

However, stellar clusters form in very dusty regions that absorb most of the visible light that the young stars emit, making them invisible to most telescopes, but not to VISTA.

In order to spot the youngest star clusters, the astronomers concentrated their search towards known star-forming areas. They found that regions that looked empty in previous visible-light surveys, actually held lots of clusters.

VISTA telescope

VISTA is an infrared survey telescope at the European Southern Observatory in Chile.

No wonder they were hidden

By using carefully tuned computer software, the team was able to remove the foreground stars appearing in front of each cluster in order to count the genuine cluster members.

Afterwards, they made visual inspections of the images to measure the cluster sizes, and for the more populous clusters they made other measurements such as distance, and the age of the stars.

“We found that … the dust in front of these clusters makes them appear 10,000 to 100 million times fainter in visible light,” explains Radostin Kurtev, another member of the team. “It’s no wonder they were hidden.”

Tip of the iceberg

Only 2,500 open clusters are known so far in the Milky Way, but astronomers think there might be as many as 30,000 still hiding behind the dust and gas.

These new 96 open clusters might be only the tip of the iceberg.

“We’ve just started to use more sophisticated automatic software to search for less concentrated and older clusters,” adds Jura Borissova, lead author of the study. “I am confident that many more are coming soon.”

Adapted from information issued by ESO. Images courtesy ESO / J. Borissova / Steven Beard (UKATC).

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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:

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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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That’s not a telescope!

IF CROCODILE DUNDEE had carried a telescope, it would have been an extremely large one … perhaps the largest in the world.

The science and engineering needed to make a telescope that has a primary mirror 10 times the size of world’s largest telescope is truly astronomical. Such telescopes, costing in excess of 1 billion Euro, are currently being designed in both Europe and the United States.

This month Prof. Jason Spyromilio, who heads the European Southern Observatory’s (ESO) Extremely Large Telescope (ELT) Project, will present a public lecture on the most ambitious of these designs…an optical telescope with a 42-metre-diameter primary mirror!

The European ELT will be over 10,000 times more powerful than any telescope in Australia, able to image planets in other star systems and directly observe the expansion of the universe, amongst many other scientific objectives.

Size comparison between the European Extremely Large Telescope and the Sydney Opera House.

Artist's impression comparing the sizes of the European Extremely Large Telescope and the Sydney Opera House.

Jason Spyromilio completed his PhD at Imperial College London before coming to Australia to join the Anglo-Australian Observatory (now the Australian Astronomical Observatory) in 1991, where he was the instrument scientist for a number of Anglo-Australian Telescope instruments (and is remembered for augmenting one of them with a Lego train set!).

He moved to ESO in 1994, and has headed the European Extremely Large Telescope Project Office since 2006 (and was the director of ESO’s La Silla Paranal Observatory 2005-2007).

Prof. Spyromilio’s main research interest is supernovae (exploding stars), but he has also worked on comets, brown dwarfs and other cosmic phenomena.

Details:

Where: Long Room, Customs House at Riverside, Brisbane

When: Monday, May 9, 2011, 6:30pm to 7:30pm

Arrangements: Doors open at 6pm. No need to book—just turn up!

Contact: Any questions, please email Andrew Stephenson a.stephenson@uq.edu.au

Refreshments: There will be complimentary drinks and nibblies following the talk, where Prof. Jason Spyromilio will be available to answer any questions

Adapted from information issued by BrisScience / University of Queensland. Images courtesy ESO.

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Hidden cosmic treasures

OBSERVATIONS MADE WITH the European Southern Observatory’s (ESO) powerful ground-based telescopes are veritable treasures, stored in a huge archive usually only visited by professional astronomers on a mission.

And yet, an amateur astrophotographer from Russia managed to uncover a real gem from ESO’s Hidden Treasures, winning a trip to Chile to observe with the Very Large Telescope and take part in the observations.

How did he manage it? And could you do the same?

This podcast episode takes you behind the scenes of ESO’s Hidden Treasures competition and shows you how a group of determined and talented amateur astrophotographers managed to find and produce stunning astronomy pictures.

Adapted from information issued by ESO.

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Going out with a bang

NGC 3582

Giant loops of gas ejected by dying stars in the star formation region NGC 3582, bear a striking resemblance to solar prominences.

GIANT LOOPS OF GAS bearing a striking resemblance to solar prominences are seen in this image of the nebula NGC 3582.

The loops are thought to have been ejected by dying stars, although new stars are also being born within this stellar nursery.

These energetic youngsters emit intense ultraviolet radiation that makes the gas in the nebula glow, producing the fiery display shown here.

NGC 3582 is part of a large star-forming region in the Milky Way, called RCW 57, close to the central plane of the Milky Way.

The famous astronomers John Herschel first spotted this complex region of glowing gas and dark dust clouds in 1834, during his stay in South Africa.

Some of the stars forming in regions like NGC 3582 are much more massive than the Sun. These monster stars emit energy at prodigious rates and have very short lives that end in the stellar explosions called supernovae.

The material ejected from these explosions creates bubbles in the surrounding gas and dust. This is the probable cause of the loops visible in this picture.

Here’s a short video that takes you on a sweeping journey into NGC 3582:

The image was captured by the Wide Field Imager on the MPG/ESO 2.2-metre telescope at European Southern Observatory’s (ESO) La Silla Observatory in Chile.

It is a false-colour image made up of separate exposures taken through multiple filters. From the Wide Field Imager, data taken through a red filter are coloured in green and red, and data taken through a filter that isolates the red glow characteristic of hydrogen are also shown in red. Additional infrared data from the Digitised Sky Survey are shown in blue.

The image was processed by ESO using the data identified by amateur astronomer Joe DePasquale, from the United States, who participated in ESO’s Hidden Treasures 2010 astrophotography competition. The competition was organised by ESO in October-November 2010, for everyone who enjoys making beautiful images of the night sky using astronomical data obtained using professional telescopes.

ESO’s Hidden Treasures 2010 competition gave amateur astronomers the opportunity to search through ESO’s vast archives of astronomical data, hoping to find a well-hidden gem that needed polishing by the entrants.

More information: Hidden Treasures

Adapted from information issued by ESO, Digitised Sky Survey 2 and Joe DePasquale.

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Really cool stars

Artist’s impression of CFBDSIR 1458+10

Artist’s impression of the pair of brown dwarfs named CFBDSIR 1458+10. Observations suggest this is the coolest pair of brown dwarfs found so far. The colder of the two (background) could have a temperature similar to that of a cup of freshly made tea.

  • Brown dwarfs are halfway between big planets and small stars
  • They don’t shine, but give off only a small amount of heat
  • Newly found brown dwarf seems to be the coldest yet discovered

ASTRONOMERS HAVE FOUND a new candidate for the coldest known star—a ‘brown dwarf’ in a binary star system that has about the same temperature as a freshly made cup of tea.

That’s hot in human terms, but extraordinarily cold for the surface of a star.

This object is cool enough to begin crossing the blurred line dividing small, cold stars from big, hot planets.

Brown dwarfs are essentially failed stars—they don’t have enough mass for gravity to trigger the nuclear reactions that make stars shine.

The newly discovered brown dwarf, identified as CFBDSIR 1458+10B, is the dimmer member of a binary brown dwarf system located just 75 light-years from Earth.

The powerful X-shooter spectrograph on the European Southern Observatory’s (ESO) Very Large Telescope (VLT) was used to show that the object was very cool by brown dwarf standards.

“We were very excited to see that this object had such a low temperature, but we couldn’t have guessed that it would turn out to be a double system and have an even more interesting, even colder [star],” said Philippe Delorme of the Institut de planétologie et d’astrophysique de Grenoble (CNRS/Université Joseph Fourier), a co-author of the paper.

Keeping its cool

CFBDSIR 1458+10 is the name of the binary system. The individual stars are known as CFBDSIR 1458+10A and CFBDSIR 1458+10B, with the latter the fainter and cooler of the two. They seem to be orbiting each other at a separation of about three times the distance between the Earth and the Sun with a period of about thirty years.

Brown dwarf binary CFBDSIR 1458+10

Actual image of the brown dwarf binary CFBDSIR 1458+10, obtained using the Laser Guide Star (LGS) Adaptive Optics system on the Keck II Telescope in Hawaii. Adaptive optics cancels out much of Earth’s atmospheric interference, improving the image sharpness by a factor of 10.

The dimmer of the two dwarfs has now been found to have a temperature of about 100 degrees Celsius — the boiling point of water, and not much different from the temperature inside a sauna.

By comparison the temperature of the surface of the Sun is about 5,500 degrees Celsius.

“At such temperatures we expect the brown dwarf to have properties that are different from previously known brown dwarfs and much closer to those of giant exoplanets—it could even have water clouds in its atmosphere,” said Michael Liu of the University of Hawaii’s Institute for Astronomy, who is lead author of the paper describing this new work.

“In fact, once we start taking images of gas-giant planets around Sun-like stars in the near future, I expect that many of them will look like CFBDSIR 1458+10B.”

Three telescopes needed

Unravelling the secrets of this unique object involved exploiting the power of three different telescopes. CFBDSIR 1458+10 was first found to be a binary using the Laser Guide Star (LGS) Adaptive Optics system on the Keck II Telescope in Hawaii.

Liu and his colleagues then employed the Canada–France–Hawaii Telescope, also in Hawaii, to determine the distance to the brown dwarf duo using an infrared camera. Finally the ESO VLT was used to study the object’s infrared spectrum and measure its temperature.

The hunt for cool objects is a very active astronomical hot topic. The Spitzer Space Telescope has recently identified two other very faint objects as other possible contenders for the coolest known brown dwarfs, although their temperatures have not been measured so precisely.

Future observations will better determine how these objects compare to CFBDSIR 1458+10B.

Liu and his colleagues are planning to observe CFBDSIR 1458+10B again to better determine its properties and to begin mapping the binary’s orbit, which, after about a decade of monitoring, should allow astronomers to determine the binary’s mass.

Adapted from information issued by ESO / Michael Liu (University of Hawaii) / L. Calçada.

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Hot, giant planet seen again

Artist's impression of Beta Pictoris b

Artist's impression of the hot, giant planet that orbits the star Beta Pictoris. Also visible is the cloud of gas and dust that encircles the star.

  • Beta Pictoris is a nearby star (63.4 light-years away) surrounded by gas and dust
  • Large, suspected planet was spotted in images taken in 2003 and 2009
  • New images have confirmed it is definitely a planet orbiting the star

IN 2009, ASTRONOMERS ANNOUNCED they had taken images of a suspected planet orbiting a nearby star.

Ordinarily, the presence of such exoplanets can be determined using various methods, but almost all of them are too small and too far away to be directly seen and imaged.

This particular planet, though, orbits a relatively nearby star called Beta Pictoris. It also happens that its orbit around the star is at right angles to our line-of-sight, making it much easier to spot.

Today, astronomers announced (in a paper published in the journal Astronomy & Astrophysics) that they have taken new images the planet, and have confirmed that its position has changed, consistent with it orbiting its star.

In the new observations, the planet—called ‘Beta Pictoris b’—was seen with the NaCo instrument on the European Southern Observatory’s (ESO) Very Large Telescope (VLT) in Chile.

The observations have also enabled the astronomers to measure its mass and the effective temperature.

Huge and hot

Located 63.4 light-years away, Beta Pic is a very young star—only about 12 million years old, compared to our Sun’s age of 4.5 billion years. It is also 75% more massive than our Sun.

Beta Pic is well known for being encircled by a large cloud of gas and dust…what astronomers call a ‘circumstellar disc’. It was actually the first star to have its disc directly imaged more than 25 years ago.

Movement of exoplanet Beta Pictoris b

Moving pictures. The exoplanet Beta Pictoris b was imaged in 2003 (left) and again in October 2009 (middle) when it had moved to the other side of the star. The new observations (right), made in March 2010, show the planet has moved yet again. (The glare of the star has been blocked out.)

In 2009, the giant planet was spotted orbiting within the disc. With an orbital distance of 8 to 15 astronomical units, Beta Pictoris b is the closest exoplanet to its star that has ever been imaged. (An astronomical unit, or AU, is a standard measurement in astronomy, being the distance between the Earth and the Sun.)

Analysing the new observations, the team have estimated the planet’s mass—around 7 to 11 times the mass of Jupiter (the largest planet in our Solar System). They’ve also estimated its temperature—between 1,100 and 1,700 degrees Celsius.

Just a youngster

The planet offers a new opportunity for astronomers to study planetary formation processes, and in particular the way planets and their stars’ circumstellar discs interact.

In fact, the new data has already told the astronomers something important about the formation of the planet (especially because the system is very young)—that the planet is still warm implies that it has retained most of the primordial heat acquired during its formation.

If it had formed in a similar way to the giant planets of our Solar System, its mass and temperature could not be explained by some models that suggest a total release of that energy.

More observations with NaCo and also with the next generation VLT instrument, SPHERE, should soon provide more details about the planet’s atmosphere and orbital properties, and about the way it influences the gas and dust cloud surrounding the star.

The team of astronomers includes M. Bonnefoy, A.-M. Lagrange, G. Chauvin, D. Ehrenreich, D. Mouillet (IPAG, Grenoble, France), A. Boccaletti, D. Rouan, D. Gratadour (LESIA-Observatoire de Paris, Meudon, France), D. Apai (Space Telescope Institute, Baltimore, USA), F. Allard (CRAL-ENS, Lyon, France), J.H.V Girard (ESO, Santiago, Chile), M. Kasper (ESO, Garching, Germany).

Adapted from information issued by Astronomy & Astrophysics. Illustration courtesy ESO / L. Calçada.

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Galaxy not so far, far away

Galaxy NGC 247

Galaxy NGC 247 has been found to be 1 million light-years nearer to us than previously thought.

  • Astronomers measure distances to galaxies using Cepheid stars
  • Their brightness is used as a cosmic ‘standard candle’
  • Method brings galaxy NGC 247 one million light-years closer

HOW FAR AWAY is this galaxy? According to astronomers, it is a lot closer than previously thought—in fact, about a million light-years closer.

Distances to nearby galaxies are measured using the properties of a particular kind of star known as a ‘Cepheid variable’.

Cepheids brighten and fade with a regular pattern. Astronomers can plot a Cepheid’s brighten/fade period and then put that into a special formula, which gives them the star’s intrinsic luminosity…that is, how bright it would be if we were up close to it.

By comparing that intrinsic brightness with the star’s actual measured brightness, astronomers can gauge how far away it is.

It’s a bit like being able to judge how far away a car is at night, based on how bright its headlights seem to be.

Astronomers refer to Cepheids as ‘standard candles’, and have used this method for many years to estimate the distances to nearby galaxies. It doesn’t work for very distant galaxies—as we look further out into space, a point is reached where individual stars cannot be made out.

But difficulties remain with the Cepheid method. Recent work has suggested that the Cepheids’ ‘period-luminosity’ relation is not as clear-cut as previously thought.

In addition, a Cepheid’s brightness can be affected by interstellar dust absorbing some of the star’s light, making it seem fainter than it really is.

Close-up of part of NGC 247

Studying Cepheid variable stars in other galaxies enables astronomers to determine the distances to those galaxies.

Dimmed by dust

NGC 247 is a spiral galaxy in the Sculptor Group of galaxies, which is the nearest collection of galaxies to the Milky Way’s own galaxy cluster, the Local Group.

But how far away is it?

One of the good things about NGC 247 is that it is close enough that individual stars can be made out in high-resolution images, making it a prime candidate for Cepheid measurements.

But the galaxy is tilted to our line of sight—we’re seeing it about halfway between face-on and edge-on. This means that its starlight, including that from the Cepheids, has to pass through a lot of the dust inside the galaxy.

An international team of astronomers known as the Araucaria Project is seeking to refine NGC 247’s Cepheid distance measurements by taking the dust into account.

Their initial findings suggest NGC 247 is over 1 million light-years nearer to us than earlier thought. The official distance now stands at a little over 11 million light-years.

The image was produced by combining a number of exposures taken (through different filters) with the Wide Field Imager on the MPG/ESO 2.2-metre telescope at the European Southern Observatory’s (ESO) La Silla Observatory in Chile.

One of the filters brings out clouds of hydrogen gas (coloured pink) along the spiral arms, indicating areas of active star formation.

Written by Jonathan Nally, SpaceInfo.com.au. Image courtesy ESO.

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Stunning blue nebula

Nebula Messier 78

Reflection nebula Messier 78 is 1,350 light-years from Earth. The blue colour comes from reflected starlight. See below for a link to the full-size image, and screen wallpapers you can download.

  • Nebula Messier 78 is 1,350 light-years from Earth
  • Blue colour comes from starlight reflected from tiny dust particles
  • Home to dozens of very young stars

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.

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 1,350 light-years away in the direction of 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 ESO Hidden Treasures competition.

See the full-size image here.

Home to young stars

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 formed.

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 small (75mm) 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 part of the object is now known as McNeil’s Nebula and it appears to be a highly variable reflection nebula around a young star.

Screen wallpapers:

Messier 78 wallpaper 1068 x 768

Messier 78 wallpaper 1280 x 1024

Messier 78 wallpaper 1600 x 1200

Adapted from information issued by ESO. Image credit: ESO and Igor Chekalin.

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