nebula Archives

May 23, 2013December 23, 2015 by Jason Major

An Amazing Anniversary Image from the VLT

A new view of the spectacular stellar nursery IC 2944 (ESO)

This Saturday will mark 15 years that the European Southern Observatory’s Very Large Telescope (VLT) first opened its eyes on the Universe, and ESO is celebrating its first-light anniversary with a beautiful and intriguing new image of the stellar nursery IC 2944, full of bright young stars and ink-black clouds of cold interstellar dust.

This is the clearest ground-based image yet of IC 2944, located 6,500 light-years away in the southern constellation Centaurus.

Emission nebulae like IC 2944 are composed mostly of hydrogen gas that glows in a distinctive shade of red, due to the intense radiation from the many brilliant newborn stars. Clearly revealed against this bright backdrop are mysterious dark clots of opaque dust, cold clouds known as Bok globules. They are named after Dutch-American astronomer Bart Bok, who first drew attention to them in the 1940s as possible sites of star formation. This particular set is nicknamed the Thackeray Globules.

Larger Bok globules in quieter locations often collapse to form new stars but the ones in this picture are under fierce bombardment from the ultraviolet radiation from nearby hot young stars. They are both being eroded away and also fragmenting, like lumps of butter dropped into a hot frying pan. It is likely that Thackeray’s Globules will be destroyed before they can collapse and form stars.

This new picture celebrates an important anniversary for the the VLT – it will be fifteen years since first light on the first of its four Unit Telescopes on May 25, 1998. Since then the four original giant telescopes have been joined by the four small Auxiliary Telescopes that form part of the VLT Interferometer (VLTI) – one of the most powerful and productive ground-based astronomical facilities in existence.

The selection of images below — one per year — gives a taste of the VLT’s scientific productivity since first light in 1998:

A selection of images from 15 years of the VLT (Credits: ESO/P.D. Barthel/M. McCaughrean/M. Andersen/S. Gillessen et al./Y. Beletsky/R. Chini/T. Preibisch)

Read more on the ESO site here, and watch an ESOCast video below honoring the VLT’s fifteen-year milestone:

Happy Anniversary VLT!

Source: ESO

May 2, 2013December 23, 2015 by Tammy Plotner

Anarchic Star Formation Found In Dust Cloud

The Danish 1.54-metre telescope located at ESO’s La Silla Observatory in Chile has captured a striking image of NGC 6559, an object that showcases the anarchy that reigns when stars form inside an interstellar cloud. Credit: ESO

If you think that breaking all the rules is cool, then you’ll appreciate one of the latest observations submitted by the Danish 1.54 meter telescope housed at ESO’s La Silla Observatory in Chile. In this thought-provoking image, you’ll see what kind of mayhem occurs when stars are forged within an interstellar nebula.

Towards the center of the Milky Way in the direction of the constellation of Sagittarius, and approximately 5000 light-years from our solar system, an expansive cloud of gas and dust await. By comparison with other nebulae in the region, this small patch of cosmic fog known as NGC 6559 isn’t as splashy as its nearby companion nebula – the Lagoon (Messier 8). Maybe you’ve seen it with your own eyes and maybe you haven’t. Either way, it is now coming to light for all of us in this incredible image.

Comprised of mainly hydrogen, this ethereal mist is the perfect breeding ground for stellar creation. As areas contained within the cloud gather enough matter, they collapse upon themselves to form new stars. These neophyte stellar objects then energize the surrounding hydrogen gas which remains around them, releasing huge amounts of high energy ultraviolet light. However, it doesn’t stop there. The hydrogen atoms then merge into the mix, creating helium atoms whose energy causes the stars to shine. Brilliant? You bet. The gas then re-emits the energy and something amazing happens… an emission nebula is created.

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This zoom starts with a broad view of the Milky Way. We head in towards the centre, where stars and the pink regions marking star formation nurseries are concentrated. We see the huge gas cloud of the Lagoon Nebula (Messier 8) but finally settle on the smaller nebula NGC 6559. The colourful closing image comes from the Danish 1.54-metre telescope located at ESO’s La Silla Observatory in Chile. Credit: ESO/Nick Risinger (skysurvey.org)/S. Guisard. Music: movetwo

In the center of the image, you can see the vibrant red ribbon of the emission nebula, but that’s not the only thing contained within NGC 6559. Here swarms of solid dust particles also exist. Consisting of tiny bits of heavier elements, such as carbon, iron and silicon, these minute “mirrors” scatter the light in multiple directions. This action causes NGC 6559 to be something more than it first appears to be… now it is also a reflection nebula. It appears to be blue thanks to the magic of a principle known as Rayleigh scattering – where the light is projected more efficiently in shorter wavelengths.

Don’t stop there. NGC 6559 has a dark side, too. Contained within the cloud are sectors where dust totally obscures the light being projected behind them. In the image, these appear as bruises and dark veins seen to the bottom left-hand side and right-hand side. In order to observe what they cloak, astronomers require the use of longer wavelengths of light – ones which wouldn’t be absorbed. If you look closely, you’ll also see a myriad of saffron stars, their coloration and magnitude also effected by the maelstrom of dust.

It’s an incredible portrait of the bedlam which exists inside this very unusual interstellar cloud…

Original Story Source: ESO News Release.

February 22, 2013December 23, 2015 by Jason Major

Bright Jets Blast Out from a Newborn Star

A young star is spotted firing jets of material out into space (ESA/Hubble & NASA. Acknowledgement: Gilles Chapdelaine)

Like very young humans, very young stars also tend to make a big mess out of the stuff around them — except in the case of stars it’s not crayon on the walls and Legos on the floor (ouch!) but rather huge blasts of superheated material that are launched from their poles far out into space.

The image above, acquired by the Hubble Space Telescope, shows one of these young stars caught in the act.

HL Tau is a relatively newborn star, formed “only” within the past several hundred thousand years. During that time it has scooped up vast amounts of gas and dust from the area around itself, forming a disc of hot, accelerated material that surrounds it. While most of this material eventually falls into the star, increasing its mass, some of it gets caught up in the star’s complex, rotating magnetic fields and is thrown out into space as high-speed jets.

As these jets plow thorough surrounding interstellar space they ram into nearby clouds of molecular gas, ionizing the material within them and causing them to glow brightly. These “shocks” are known as Herbig-Haro objects, after researchers George Herbig and Guillermo Haro who each discovered them independently in the early 1950s.

Detail of HH 151's jet — Detail of HH 151’s jet

In this Hubble image HH 151 is visible as a multiple-lobed cone of material fired away from HL Tau, with the leftover glows from previous outbursts dimly illuminating the rest of the scene.

The material within these jets can reach speeds of several hundred to a thousand kilometers a second. They can last anywhere from a few years to a few thousand years.

HH 151 is embedded within the larger star-forming region LDN 1551, located about 450 light-years away in the constellation Taurus. LDN 1551 is a stellar nursery full of dust, dark nebulae, newborn stars… and Herbig-Haro objects like HH 151.

(Hey, if baby stars are going to make a mess at least they can do it in the nursery.)

February 22, 2013December 23, 2015 by Elizabeth Howell

In Reality, Nebulae Offer No Place for Spaceships to Hide

The nebulas in Battlestar: Blood and Chrome make for nice scenery, but they're a lot brighter than the truth, according to a Harvard astronomer. Credit: Battlestar Galactica: Blood and Chrome/Machinima (screencap)

In the Battlestar: Galactica universe, nebulas are a nifty spot to hide from the Cylons that are plotting to kill humanity. There’s just one problem with the hypothesis, though — these diffuse areas of gas in our universe are actually very faint, even if you get close up. Probably too faint for a hiding spot.

Prequel Battlestar Galactica: Blood and Chrome (released on DVD this week) shows the young William Adama flying around the universe with pretty nebulas in the background. That’s not anywhere near the truth, Harvard astronomer Peter Williams told Universe Today.

In an e-mail, Williams explained that bright nebulas are a common misperception seen in Star Wars, Star Trek and a host of other sci-fi series.

The big issue is that nebulae are just too faint for the human eye to see. And while it’s tempting to think that they’d look brighter from up close, in fact this isn’t actually true — they actually look just as bright from any distance! This is a law of optics, known in the jargon as the “conservation of surface brightness”. The key is that there are two competing effects in play. Imagine that you can see a nebula that’s, say, the size of the full moon.

Yes, if you get closer, your eye will receive more total power from the nebula. But the nebula will also look bigger, so that energy will be spread out over a larger visual area (technically: “solid angle”). The physics tells you that the power per solid angle in fact stays exactly the same, and this quantity is precisely the “brightness” of an object. So if nebula are too faint for to see from Earth with the naked eye — and they are — getting up close and personal doesn’t help any.

Those bright colors surrounding Battlestar's ships are not actually what you would see if nestled in a nebula, according to Harvard astronomer. Credit: Battlestar Galactica/SciFi (screencap) — The opening sequence in Battlestar: Galactica shows the ships hiding in a bright nebula. Credit: Battlestar Galactica/SciFi (screencap)

Further, Williams, explains, the bright colors we’re used to seeing in Hubble Space Telescope images are just an approximation of what a nebula actually looks like.

Reproduced images of nebulae don’t portray their colors accurately. As you may know, some astronomical images use “false color” to represent wavelengths of light that humans can’t even see. This does happen with images of nebulae, but nebulae really are colorful, and many nebula images try to reproduce those colors faithfully. No current reproduction, however, can be truly accurate.

The Crab Nebula. Image credit: NASA/Hubble Space Telescope.

The problem is that the colorful nebular emission comes from reactions that produce light at a few, specific wavelengths; meanwhile, our inks and pixels emit over much broader wavelength ranges. We can mix these broad ranges in ways that approximate the narrow ones, but the results aren’t quite the same.

For an entertaining look at the science of nebulas, Williams recommends this entertaining video by astronomer Phil Plait, a long-time friend of Universe Today who is best known for his Bad Astronomy blog (now at Slate). “If you were inside [the nebula and looked down], you wouldn’t see it,” Plait says in this 2008 clip.

Guess it’s time to find another spot to hide.

February 10, 2013December 23, 2015 by Jason Major

A Cosmic Snake for Chinese New Year

Barnard 72 - the "Snake Nebula" (Wikisky.org)

Gong Hey Fat Choy! Today marks the beginning of the Chinese New Year and what better way to celebrate the Year of the Black Snake than with a look at an enormous shadowy cosmic serpent, the Snake Nebula!

Also known as Barnard 72, the Snake Nebula is a meandering lane of dark dust located about 650 light-years away in the constellation Ophiuchus. Several light-years long, its opaque dust blocks our view of stars within the central bulge of the galaxy… but also reveals its presence since that region of the sky is literally filled with stars.

The Snake Nebula is part of the larger Dark Horse Nebula.

The bright star seen in the image just below the snake’s middle (looks like it may have just had dinner!) is HD 157398, a giant orange star 538 light-years from Earth. Here it shines brightly, but in the sky its visible magnitude is 6.67 — just a bit dimmer than what can be seen with the naked eye under the darkest skies.

Image via Wikisky.org.

February 8, 2013December 23, 2015 by Jason Major

A Cosmic Seagull’s Star-Studded Wings

Bright stars and vast clouds of dust and gas illuminate the “wings” of the Seagull Nebula (ESO)

These glowing red clouds are just a small part of the wings of an enormous bird — the Seagull Nebula, a band of gas and dust 3,400 light-years away that shines from UV light radiating from hot newborn stars.

This image was made from observations with the MPG/ESO 2.2-meter telescope at the ESO La Silla Observatory in Chile. See the full wide-field view of the Seagull Nebula below.

Wide-field view of the Seagull Nebula. The white box is the area seen at top. North is up in this view. (ESO/Digitized Sky Survey 2. Acknowledgement: Davide De Martin)

The Seagull Nebula (IC 2177) is a vaguely bird-shaped region of gas and dust clouds located between the constellations Canis Major and Monoceros. The detail image at the top of this article is located along the upper edge of the gull’s lower wing, and is separately cataloged as Sharpless 2-296.

The bright red glow is the result of ionized hydrogen energized by the radiation from the several hot, bright young stars seen in the image. H II regions like the Seagull Nebula are signs of ongoing star formation in a galaxy — in a spiral galaxy like our Milky Way, these dust clouds are scattered throughout the arms. In fact, it was observations of such nebulae in the 1950s by Stewart Sharpless that helped determine the spiral structure of the Galaxy.

The silhouettes of dark, dense clouds closer to Earth block the red hydrogen glow from more distant areas of Sharpless 2-296.

Weekly Space Hangout – January 25, 2013

Back by popular demand… the Weekly Space Hangout has returned. This is a weekly broadcast on Google+, where I’m joined by a wide and varied team of space and astronomy journalists to discuss the big breaking stories this week.

This week, we talked about:

We record the Weekly Space Hangout every Friday on Google+ at 12:00 pm PST / 3:00 pm EST / 2000 GMT. You’ll want to circle Cosmoquest on Google+ to find out when we’re recording next. The audio for the Weekly Space Hangout is also released to the Astronomy Cast podcast feed.

December 18, 2012December 23, 2015 by Jason Major

Behold! Hubble’s Heavenly Holiday “Ornament”

Planetary nebula NGC 5189 as seen by Hubble’s Wide Field Camera 3. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

It may be just a tad too big to hang on your tree but this bright, twisted planetary nebula would make a beautiful holiday ornament… if scaled a bit down to size, of course.

(Click the image to see it in its full festive glory!)

NGC 5189 is a planetary nebula that lies 1,800 light-years away in the southern constellation Musca. The gorgeous image above, acquired by Hubble’s Wide Field Camera 3 on October 8, 2012, shows the glowing streamers of oxygen, sulfur and hydrogen that are being blown far into space from the hot star star at its heart — HD 117622 (at right.)

The expelled gas forms a double structure, with a series of central blue lobes surrounded by a twisted helix of bright streamers, called radial filaments. These filaments are the result of fast-moving material from the star impacting previously expelled, slower-moving gas, which becomes visible due to ionizing radiation.

The twisted shapes — as opposed to the circular or spherical structures found in many planetary nebulae — may be the result of an unseen binary partner to HD 117622, which over time would affect its rotational orientation.

“The likely mechanism for the formation of this planetary nebula is the existence of a binary companion to the dying star,” said scientist Kevin Volk in a Gemini Observatory article from 2006. “Over time the orbits drift due to precession and this could result in the complex curves on the opposite sides of the star.”

The surrounding stars in the image were captured in visible and near-infrared light.

Read more on the Hubble site here, and check out a video below that zooms into the region of the sky where NGC 5189 is located:

Video credit: NASA, ESA, and G. Bacon (STScI)

November 25, 2012December 23, 2015 by Jason Major

Orion Revisited: Astronomers Find New Star Cluster in Front of the Orion Nebula

The well-known star-forming region of the Orion Nebula. Credit: Canada-France-Hawaii Telescope / Coelum (J.-C. Cuillandre & G. Anselmi)

Precise distances are difficult to gauge in space, especially within the relatively local regions of the Galaxy. Stars which appear close together in the night sky may actually be separated by many hundreds or thousands of light-years, and since there’s only a limited amount of space here on Earth with which to determine distances using parallax, astronomers have to come up with other ways to figure out how far objects are, and what exactly is in front of or “behind” what.

Recently, astronomers using the 340-megapixel MegaCam on the Canada-France-Hawaii Telescope (CFHT) observed the star-forming region of the famous Orion nebula — located only about 1,500 light-years away — and determined that two massive groupings of the nebula’s stars are actually located in front of the cluster as completely separate structures… a finding that may ultimately force astronomers to rethink how the many benchmark stars located there had formed.

Although the Orion nebula is easily visible with the naked eye (as the hazy center “star” in Orion’s three-star sword, hanging perpendicular below his belt) its true nebulous nature wasn’t identified until 1610. As a vast and active star-forming region of bright dust and gas located a mere 1,500 light-years distant, the various stars within the Orion Nebula Cluster (ONC) has given astronomers invaluable benchmarks for research on many aspects of star formation.

Now, CFHT observations of the Orion nebula conducted by Dr. Hervé Bouy of the European Space Astronomy Centre (ESAC) and Centre for Astrobiology (CSIC) and Dr. João Alves of the Institut für Astronomie (University of Vienna) have shown that a massive cluster of stars known as NGC 1980 is actually in front of the nebula, and is an older group of approximately 2,000 stars that is separate from the stars found within the ONC… as well as more massive than once thought.

“It is hard to see how these new observations fit into any existing theoretical model of cluster formation, and that is exciting because it suggests we might be missing something fundamental.”

– Dr. João Alves, Institut für Astronomie, University of Vienna

In addition their observations with CFHT — which were combined with previous observations with ESA’s Herschel and XMM-Newton and NASA’s Spitzer and WISE — have led to the discovery of another smaller cluster, L1641W.

According to the team’s paper, “We find that there is a rich stellar population in front of the Orion A cloud, from B-stars to M-stars, with a distinct 1) spatial distribution; 2) luminosity function; and 3) velocity dispersion from the reddened population inside the Orion A cloud. The spatial distribution of this population peaks strongly around NGC 1980 (iota Ori) and is, in all likelihood, the extended stellar content of this poorly studied cluster.”

The findings show that what has been known as Orion Nebula Cluster is actually a combination of older and newer groups of stars, possibly calling for a “revision of most of the observables in the benchmark ONC region (e.g., ages, age spread, cluster size, mass function, disk frequency, etc.)”

“We must untangle these two mixed populations, star by star, if we are to understand the region, and star formation in clusters, and even the early stages of planet formation,” according to co-author Dr. Hervé Bouy.

The team’s article “Orion Revisited” was published in the November 2012 Astronomy & Astrophysics journal. Read the CFHT press release here.

The Canada-France-Hawaii Telescope’s Mauna Kea summit dome in September 2009. Credit: CFHT/Jean-Charles Cuillandre

Inset image: Orion nebula seen in optical – where the molecular cloud is invisible – and infrared, which shows the cloud. Any star detected in the optical in the line of sight over the region highlighted in the right panel must therefore be located in the foreground of the molecular cloud. Credit: J. Alves & H. Bouy.

September 26, 2012December 23, 2015 by Jason Major

Take a Gander at a Cosmic Gull

The head and “eye” of the Seagull Nebula (ESO)

This colorful new image from ESO’s La Silla Observatory highlights the heart of a shining stellar nursery located between the constellations Monoceros and Canis Major. Officially named Sharpless 2-292, the cloud of gas and dust forms the “head” of the Seagull Nebula (IC 2177) and gets its glow from the energy emitted by the young, bright star within its “eye”.

A wide-angle image of the Seagull Nebula shows the soaring birdlike shape that gives it its nickname. The cloud seen above forms the gull’s head.

A wide-field view of the Seagull Nebula from the ESO’s Digitized Sky Survey 2 (ESO/Digitized Sky Survey 2. Acknowledgement: Davide De Martin)

The wings of this gull span an impressive 100 light-years from tip to tip. A birthplace for new stars, the nebula is located within our galaxy about 3,700 light-years away.

For an idea of how far that is, if the distance between the Sun and Earth were scaled down to 1 inch (2.5 cm) and you were standing in New York City, the stars in the Seagull Nebula would be in Paris, France (considering the most direct flight route.)

Powerful radiation from young stars causes the surrounding hydrogen gas to glow with a red color. Light from the hot blue-white stars also gets scattered off tiny dust particles in the nebula to create a blue haze.