Lying over 110 million light-years away from Earth in the constellation of Antlia (The Air Pump) is the spiral galaxy IC 2560, shown here in an image from NASA/ESA Hubble Space Telescope. At this distance it is a relatively nearby spiral galaxy, and is part of the Antlia cluster — a group of over 200 galaxies held together by gravity. This cluster is unusual; unlike most other galaxy clusters, it appears to have no dominant galaxy within it.
In this image, it is easy to spot IC 2560’s spiral arms and barred structure. This spiral is what astronomers call a Seyfert-2 galaxy, a kind of spiral galaxy characterised by an extremely bright nucleus and very strong emission lines from certain elements — hydrogen, helium, nitrogen, and oxygen. The bright centre of the galaxy is thought to be caused by the ejection of huge amounts of super-hot gas from the region around a central black hole.
There is a story behind the naming of this quirky constellation — Antlia was originally named antlia pneumatica by French astronomer Abbé Nicolas Louis de Lacaille, in honour of the invention of the air pump in the 17th century.
This image, captured by ESO’s Very Large Telescope (VLT) at Paranal, shows a small part of the well-known emission nebula, NGC 6357, located some 8000 light-years away, in the tail of the southern constellation of Scorpius (The Scorpion). The image glows with the characteristic red of an H II region, and contains a large amount of ionised and excited hydrogen gas.
The cloud is bathed in intense ultraviolet radiation — mainly from the open star cluster Pismis 24, home to some massive, young, blue stars — which it re-emits as visible light, in this distinctive red hue.
The cluster itself is out of the field of view of this picture, its diffuse light seen illuminating the cloud on the centre-right of the image. We are looking at a close-up of the surrounding nebula, showing a mesh of gas, dark dust, and newly born and still forming stars.
The NASA/ESA Hubble Space Telescope has captured this image of PGC 10922, an example of a lenticular galaxy — a galaxy type that lies on the border between ellipticals and spirals.
Seen face-on, the image shows the disc and tightly-wound spiral structures of dark dust encircling the bright centre of the galaxy. There is also a remarkable outer halo of faint wide arcs or shells extending outwards, covering much of the picture. These are likely to have been formed by a gravitational encounter or even a merger with another galaxy. Some dust also appears to have escaped from the central structure and has spread out across the inner shells.
An extraordinarily rich background of more remote galaxies can also be seen in the image.
A version of this image was entered into the Hubble’s Hidden Treasures image processing competition by contestant Judy Schmidt.
At first glance, this Hubble picture appears to capture two space colossi entangled in a fierce celestial battle, with two galaxies entwined and merging to form one. But this shows just how easy it is to misinterpret the jumble of sparkling stars and get the wrong impression — as it’s all down to a trick of perspective.
By chance, these galaxies appear to be aligned from our point of view. In the foreground, the irregular dwarf galaxy PGC 16389 — seen here as a cloud of stars — covers its neighbouring galaxy APMBGC 252+125-117, which appears edge-on as a streak. This wide-field image also captures many other more distant galaxies, including a quite prominent face-on spiral towards the right of the picture.
A version of this image was entered into the Hubble’s Hidden Treasures image processing competition by contestant Luca Limatola.
A piercingly bright curtain of stars is the backdrop for this beautiful image taken by astronomer Håkon Dahle. The silhouetted figure in the foreground is Håkon himself surrounded by just a couple of the great dark domes that litter the mountain of ESO’s La Silla Observatory.
Many professional astronomers are also keen photographers — and who could blame them? ESO sites in the Atacama Desert are among the best places on Earth for observing the stars, and for the same reason, are amazing places for photographing the night sky.
Håkon took these photos while on a week-long observing run at the MPG/ESO 2.2 -telescope. During this time, the telescope was occasionally handed over to a different observing team, giving Håkon the opportunity to admire the starry night — as well as to capture it for the rest of us to see.
The Milky Way is brighter in the Southern Hemisphere than in the North, because of the way our planet’s southern regions point towards the dense galactic centre. But even in the South, the Milky Way in the night sky is quite faint in the sky. For most of us, light pollution from our cities and even the Moon can outshine the faint glow of the galaxy, hiding it from view.
One of the best aspects of La Silla Observatory is that it is far away from bright city lights, giving it some of the darkest night skies on Earth. The atmosphere is also very clear, so there is no haze to further muddy your vision. The skies at La Silla are so dark that it is possible to see a shadow cast by the light of the Milky Way alone.
Håkon submitted this photograph to the Your ESO Pictures Flickr group. The Flickr group is regularly reviewed and the best photos are selected to be featured in our popular Picture of the Week series, or in our gallery.
This beautiful image portrays the galaxies NGC 799 (below) and NGC 800 (above) located in the constellation of Cetus (The Whale). This pair of galaxies was first observed by the American astronomer Lewis Swift back in 1885.
Located at a distance of about 300 million light-years, our face-on view allows us to clearly appreciate their shapes. Like the Milky Way — our galaxy — these objects are both spiral galaxies, with characteristic long arms winding towards a bright bulge at the centre. In the prominent spiral arms, a large number of hot, young, blue stars are forming in clusters (tiny blue dots seen in the image) whereas in the central bulge a large group of cooler, redder, old stars are packed into a compact, almost spherical region.
At first glance, these galaxies look rather similar, but the devil is in the detail. Apart from the obvious difference in size, only NGC 799 has a bar structure, extending from its central bulge, and the spiral arms wind out from the ends of the bar. Galactic bars are thought to act as a mechanism that channels gas from the spiral arms to the centre, intensifying star formation. A supernova was also observed in NGC 799 in 2004, and was given the name SN2004dt.
Another interesting differentiating feature is the number of spiral arms. The small NGC 800 has three bright, knotty spiral arms, whilst NGC 799 only has two relatively dim, but broad spiral arms. These start at the end of the bar and wrap nearly completely around the galaxy forming a structure that looks almost like a ring.
While it might seem that this image depicts two impressive close spiral galaxies coexisting in an everlasting peace, nothing can be further than the truth. We could be just witnessing the calm before the storm. We don’t know exactly what the future will bring, but typically, when two galaxies are close enough, they interact over hundreds of millions of years by means of gravitational disturbances. In some cases, only minor interactions occur, causing shape distortions, but sometimes galaxies collide, merging to form a single, new and larger galaxy.
The image was obtained using the FORS1 instrument on the 8.2-metre ESO Very Large Telescope (VLT) atop Cerro Paranal, Chile. It combines exposures taken through three filters (B, V, R).
Five asteroids can also be seen — can you find them all? The asteroids moved between the different exposures leaving colourful streaks in the image.
Astronomical pictures sometimes deceive us with tricks of perspective. Right in the centre of this image, two spiral galaxies appear to be suffering a spectacular collision, with a host of stars appearing to flee the scene of the crash in a chaotic stampede.
However, this is just a trick of perspective. It is true that two spiral galaxies are colliding, but they are millions of light-years away, far beyond the cloud of blue and red stars near the merging spiral. This sprinkling of stars is actually an isolated, irregular dwarf galaxy named ESO 489-056. The dwarf galaxy is actually much more distant than many bright stars in the foreground of the image, which are located much closer to us, in the Milky Way.
ESO 489-056 is located 16 million light-years from Earth in the constellation of Canis Major (The Greater Dog), in our local Universe. It is composed of a few billion red and blue stars — a very small number when compared to galaxies like the Milky Way, which is estimated to contain around 200 to 400 billion stars, or the Andromeda Galaxy, which contains a mind-boggling one trillion.
A version of this image was entered into the Hubble’s Hidden Treasures image processing competition by contestant Luca Limatola.
Don’t be fooled by the title; the mysterious, almost mystical bright light emerging from these thick, ominous clouds is actually a telltale sign of star formation. Here, a very young star is being born in the guts of the dark cloud LDN 43 — a massive blob of gas, dust, and ices, gathered 520 light-years from Earth in the constellation of Ophiuchus (The Serpent Bearer).
Stars are born from cosmic dust and gas, which floats freely in space until gravity forces it to bind together. The hidden newborn star in this image, revealed only by light reflected onto the plumes of the dark cloud, is named RNO 91. It is what astronomers call a pre-main sequence star, meaning that it has not yet started burning hydrogen in its core.
The energy that allows RNO 91 to shine comes from gravitational contraction. The star is being compressed by its own weight until, at some point, a critical mass will be reached and hydrogen, its main component, will begin to fuse together, releasing huge amounts of energy in the process. This will mark the beginning of adulthood for the star. But even before this happens the adolescent star is bright enough to shine and generate powerful stellar winds, emitting intense X-ray and radio emission.
RNO 91 is a variable star around half the mass of the Sun. Astronomers have been able to observe the existence of a dusty, icy disc surrounding it, stretching out to over 1700 times the distance from Earth to the Sun. It is believed that this disc may host protoplanets — planets in the process of being formed — and will eventually evolve into a fully-fledged planetary system.
This image is based on data gathered by the NASA/ESA Hubble Space Telescope. A version of this image was entered into the Hubble’s Hidden Treasures image processing competition by contestant Judy Schmidt.
This photo shows the view to the east from Paranal Observatory, seconds after the Sun has disappeared behind the horizon. The orange glow of the sunset can be seen against the 1.8-metre VLT Auxiliary Telescopes, and the almost full Moon is hanging in the sky. But the image is more interesting still, thanks to an atmospheric phenomenon known as the Belt of Venus.
The grey-bluish shadow above the horizon is the shadow of the Earth, and right above it is a pinkish glow. This phenomenon is produced by the reddened light of the setting Sun being backscattered by the Earth’s atmosphere. As well as right after sunset, this atmospheric effect can also be seen shortly before sunrise. A very similar effect can also be observed during a total solar eclipse.
The telescopes shown in the image are three of the four 1.8-metre Auxiliary Telescopes, housed in ultra-compact mobile enclosures. These telescopes are dedicated to interferometric observations, when two or more telescopes work together, forming a virtual mirror and thus allowing astronomers to see much finer details than can be seen with the individual telescopes working independently.
Carolin Liefke took this photo during a visit to Paranal, and submitted it to the Your ESO Pictures Flickr group. The Flickr group is regularly reviewed and the best photos are selected to be featured in our popular Picture of the Week series, or in our gallery. Carolin works at the Haus der Astronomie (House of Astronomy) centre for astronomy education and outreach in Heidelberg, Germany, and is a member of the ESO Science Outreach Network (ESON). ESON brings ESO news to Member States and other countries by translating press releases and providing a point of contact for local media.
In this artist’s impression, a disk of dusty material leftover from star formation girds two young stars like a hula hoop. As the two stars whirl around each other, they periodically peek out from the disk, making the system appear to “blink” every 93 days. Image credit: NASA/JPL-Caltech › Full image and caption
Astronomers using NASA’s Spitzer Space Telescope have spotted a young stellar system that “blinks” every 93 days. Called YLW 16A, the system likely consists of three developing stars, two of which are surrounded by a disk of material left over from the star-formation process.
As the two inner stars whirl around each other, they periodically peek out from the disk that girds them like a hula hoop. The hoop itself appears to be misaligned from the central star pair, probably due to the disrupting gravitational presence of the third star orbiting at the periphery of the system. The whole system cycles through bright and faint phases, with the central stars playing a sort of cosmic peek-a-boo as the tilted disk twirls around them. It is believed that this disk should go on to spawn planets and the other celestial bodies that make up a solar system.
Spitzer observed infrared light from YLW 16A, emitted by the warmed gas and dust in the disk that still swathes the young stars. Other observations came from the ground-based 2MASS survey, as well as from the NACO instrument at the European Southern Observatory’s Very Large Telescope in Chile.
YLW 16A is the fourth example of a star system known to blink in such a manner, and the second in the same star-forming region Rho Ophiuchus. The finding suggests that these systems might be more common than once thought. Blinking star systems with warped disks offer scientists a way to study how planets form in these environments. The planets can orbit one or both of the stars in the binary star system. The famous science fictional planet Tatooine in “Star Wars” orbits two stars, hence its double sunsets. Such worlds are referred to as circumbinary planets. Astronomers can record how light is absorbed by planet-forming disks during the bright and faint phases of blinking stellar systems, which in turn reveals information about the materials that comprise the disk.
"These blinking systems offer natural probes of the binary and circumbinary planet formation process," said Peter Plavchan, a scientist at the NASA Exoplanet Science Institute and Infrared Processing and Analysis Center at the California Institute of Technology, Pasadena, Calif., and lead author of a new paper accepted for publication in Astronomy & Astrophysics.
NASA’s Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA’s Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at Caltech. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center. Caltech manages JPL for NASA. For more information about Spitzer, visithttp://spitzer.caltech.edu and http://www.nasa.gov/spitzer .
Written by Adam Hadhazy Contact: Whitney Clavin 818-354-4673 Jet Propulsion Laboratory, Pasadena, Calif. firstname.lastname@example.org
29 July 2013 Like car tail lights streaking through a busy city at night, this unique image records over a thousand movements made by ESA’s XMM-Newton space telescope as it shifts its gaze from one X-ray object to another.
Orbiting in space since 1999, XMM-Newton is studying high-energy phenomena in the Universe, such as black holes, neutron stars, pulsars and stellar winds.
Even when moving from object to object, the space telescope collects data. These slews are represented by the bright strips of X-ray data in this image, which records over 1200 individual slews between 2001 and 2012, and covers about 62% of the sky.
It is a mosaic of 73 178 individual images of 1 x 0.5 degrees and is shown in Galactic projection, with the Galactic plane lying across the centre of the image.
A number of well-known X-ray sources are seen in the image. The brightest feature, lying in the Galactic plane at the right of the image, is the Vela supernova remnant, which occupies an area of sky 150 times larger than the full Moon.
On the opposite side, to the left of the Galactic plane, is the Cygnus Loop, an expanding shock wave caused by a star that exploded as a supernova less than 15 000 years ago.
Just above the centre of the image is the powerful X-ray source known as Scorpius X-1, the first source to be discovered in X-rays in 1962. Lying about 9000 light-years from Earth, it is the strongest source of X-rays in the sky, aside from our own Sun.
Nestled in the south ecliptic pole within the concentrated region of overlapping slews at the bottom right of the image are the Small and Large Magellanic Clouds, dwarf galaxies that our part of our Milky Way Galaxy’s local neighbourhood.
The full Slew Survey Catalogue can be accessed here. Furthermore, the XMM-NewtonSerendipitous Source Catalogue has also been recently updated and now contains more than half a million X-ray sources.
Another treasure unearthed from the Hubble archives, this beautiful image shows a spiral galaxy named NGC 4517. Slightly bigger than our Milky Way, it is seen edge-on, crowned by a very bright star. The star is actually much closer to us than the galaxy, explaining why it appears to be so big and bright in the picture.
NGC 4517 is located approximately 40 million light-years away in the constellation of Virgo (The Virgin). It has a bright centre, but this is not visible in this Hubble image. Its orientation has led to it being included in many studies of globular clusters, clumps of stars that orbit the centres of galaxies like satellites.
The galaxy was discovered in 1784 by William Herschel, who described this region as having “a pretty bright star situated exactly north of the centre of an extended milky ray”. Of course the “milky ray” seen by Herschel is actually this spiral galaxy, but with his 17th century observing gear he could only tell that there a fuzzy, blurry structure below the much brighter star.
This image is composed from visible and infrared light gathered by NASA/ESA Hubble Space Telescope. A version of this image was entered into the Hubble’s Hidden treasures image processing competition by contestant Gilles Chapdelaine.
Spiral galaxies are usually very aesthetically appealing objects, and never more so than when they appear face-on. And this image is a particularly splendid example: it is the grand design spiral galaxy Messier 100, located in the southern part of the constellation of Coma Berenices, and lying about 55 million light-years from Earth.
While Messier 100 shows very well defined spiral arms, it also displays the faintest of bar-like structures in the centre, which classifies this as type SAB. Although it is not easily spotted in the image, scientists have been able to confirm the bar’s existence by observing it in other wavelengths.
This very detailed image shows the main features expected in a galaxy of this type: huge clouds of hydrogen gas, glowing in red patches when they re-emit the energy absorbed from newly born, massive stars; the uniform brightness of older, yellowish stars near the centre; and black shreds of dust weaving through the arms of the galaxy.
Messier 100 is one of the brightest members of the Virgo Cluster, which is the closest cluster of galaxies to our galaxy, the Milky Way, containing over 2000 galaxies, including spirals, ellipticals, and irregulars. This picture is a combination of images from the FORS instrument on ESO’s Very Large Telescope at Paranal Observatory in Chile, taken with red (R), green (V) and blue (B) filters.
NASA's Wise Finds Mysterious Centaurs May Be Comets
New observations from NASA’s NEOWISE project reveal the hidden nature of centaurs, objects in our solar system that have confounded astronomers for resembling both asteroids and comets. The centaurs, which orbit between Jupiter and Neptune, were named after the mythical half-horse, half-human creatures called centaurs due to their dual nature. This artist’s concept shows a centaur creature together with asteroids on the left and comets at right. Image credit: NASA/JPL-Caltech
PASADENA, Calf. — The true identity of centaurs, the small celestial bodies orbiting the sun between Jupiter and Neptune, is one of the enduring mysteries of astrophysics. Are they asteroids or comets? A new study of observations from NASA’s Wide-field Infrared Survey Explorer (WISE) finds most centaurs are comets.
Until now, astronomers were not certain whether centaurs are asteroids flung out from the inner solar system or comets traveling in toward the sun from afar. Because of their dual nature, they take their name from the creature in Greek mythology whose head and torso are human and legs are those of a horse.
"Just like the mythical creatures, the centaur objects seem to have a double life," said James Bauer of NASA’s Jet Propulsion Laboratory in Pasadena, Calif. Bauer is lead author of a paper published online July 22 in the Astrophysical Journal. "Our data point to a cometary origin for most of the objects, suggesting they are coming from deeper out in the solar system."
"Cometary origin" means an object likely is made from the same material as a comet, may have been an active comet in the past, and may be active again in the future.
The findings come from the largest infrared survey to date of centaurs and their more distant cousins, called scattered disk objects. NEOWISE, the asteroid-hunting portion of the WISE mission, gathered infrared images of 52 centaurs and scattered disk objects. Fifteen of the 52 are new discoveries. Centaurs and scattered disk objects orbit in an unstable belt. Ultimately, gravity from the giant planets will fling them either closer to the sun or farther away from their current locations.
Although astronomers previously observed some centaurs with dusty halos, a common feature of outgassing comets, and NASA’s Spitzer Space Telescope also found some evidence for comets in the group, they had not been able to estimate the numbers of comets and asteroids.
Infrared data from NEOWISE provided information on the objects’ albedos, or reflectivity, to help astronomers sort the population. NEOWISE can tell whether a centaur has a matte and dark surface or a shiny one that reflects more light. The puzzle pieces fell into place when astronomers combined the albedo information with what was already known about the colors of the objects. Visible-light observations have shown centaurs generally to be either blue-gray or reddish in hue. A blue-gray object could be an asteroid or comet. NEOWISE showed that most of the blue-gray objects are dark, a telltale sign of comets. A reddish object is more likely to be an asteroid.
"Comets have a dark, soot-like coating on their icy surfaces, making them darker than most asteroids," said the study’s co-author, Tommy Grav of the Planetary Science Institute in Tucson, Ariz. "Comet surfaces tend to be more like charcoal, while asteroids are usually shinier like the moon."
The results indicate that roughly two-thirds of the centaur population are comets, which come from the frigid outer reaches of our solar system. It is not clear whether the rest are asteroids. The centaur bodies have not lost their mystique entirely, but future research from NEOWISE may reveal their secrets further.
JPL, managed by the California Institute of Technology in Pasadena, managed and operated WISE for NASA’s Science Mission Directorate. The NEOWISE portion of the project was funded by NASA’s Near Earth Object Observation Program. WISE completed its key mission objective, two scans of the entire sky, in 2011 and has been hibernating in space since then.
This dynamic image shows the New Technology Telescope (NTT) located at ESO’s La Silla Observatory in Chile. The distinctively shaped enclosure of the telescope appears blurred by movement in the picture, as the telescope rotates to point at its desired target. The photo was taken with a 30-second exposure.
One of the first things you notice in this picture is that the telescope building has a peculiar angular shape on the outside, rather than the more common rounded dome design usually seen. Its design features have been much copied, including by ESO’sVery Large Telescope, but they were groundbreaking when the telescope was inaugurated in 1989.
The NTT’s revolutionary design targets optimal image quality, for instance, through carefully controlled ventilation, which optimises airflow across the NTT, minimising the blurring caused by air turbulence inside. Just visible in the blur of this image are the large flaps that form a key part of this system.
Another feature that was advanced at the time of its construction is the NTT’s mirror. While, at 3.58 metres in diameter, it was never considered particularly large, its design was highly innovative. The mirror is flexible, and can be adjusted in real time to maintain a perfect shape, so no flexing or sagging can harm the image quality. ESO and the NTT were pioneers in using this technology, called active optics, and it is now a standard feature of modern telescopes.
Currently, the NTT has two different instruments that astronomers can use to conduct their observations: SOFI (short for the Son of ISAAC, a VLT instrument), which is an infrared spectrograph and imaging camera, and EFOSC2, a spectrograph and camera designed to detect faint objects.
The La Silla Observatory is located in the southern part of the Atacama Desert, 600 kilometres north of Santiago de Chile and at an altitude of 2400 metres.
The image was taken by Malte Tewes, an astronomer at the Ecole Polytechnique Fédérale de Lausanne, Switzerland.
Malte submitted this photograph to the Your ESO Pictures Flickr group. The Flickr group is regularly reviewed and the best photos are selected to be featured in our popular Picture of the Week series, or in our gallery.
This striking cosmic whirl is the centre of galaxy NGC 524, as seen with the NASA/ESA Hubble Space Telescope. This galaxy is located in the constellation of Pisces, some 90 million light-years from Earth.
NGC 524 is a lenticular galaxy. Lenticular galaxies are believed to be an intermediate state in galactic evolution — they are neither elliptical nor spiral. Spirals are middle-aged galaxies with vast, pinwheeling arms that contain millions of stars. Along with these stars are large clouds of gas and dust that, when dense enough, are the nurseries where new stars are born. When all the gas is either depleted or lost into space, the arms gradually fade away and the spiral shape begins to weaken. At the end of this process, what remains is a lenticular galaxy — a bright disc full of old, red stars surrounded by what little gas and dust the galaxy has managed to cling on to.
This image shows the shape of NGC 524 in detail, formed by the remaining gas surrounding the galaxy’s central bulge. Observations of this galaxy have revealed that it maintains some spiral-like motion, explaining its intricate structure.
A version of this image was entered into the Hubble’s Hidden Treasures image processing competition by contestant Judy Schmidt.
A snow line has been imaged in a far-off infant planetary system for the very first time. The snow line, located in the disc around the Sun-like star TW Hydrae, promises to tell us more about the formation of planets and comets, the factors that decide their composition, and the history of the Solar System. The results are published today in Science Express.
Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have taken the first ever image of the snow line in an infant planetary system. On Earth, snow lines form at high altitudes where falling temperatures turn the moisture in the air into snow. This line is clearly visible on a mountain, where the snow-capped summit ends and the rocky face begins.
The snow lines around young stars form in a similar way, in the distant, colder reaches of the dusty discs from which planetary systems form. Starting from the star and moving outwards, water (H2O) is the first to freeze, forming the first snow line. Further out from the star, as temperatures drop, more exotic molecules can freeze and turn to snow, such as carbon dioxide (CO2),methane (CH4), and carbon monoxide (CO). These different snows give the dust grains a sticky outer coating and play an essential role in helping the grains to overcome their usual tendency to break up in collisions, allowing them to become the crucial building blocks of planets and comets. The snow also increases how much solid matter is available and may dramatically speed up the planetary formation process.
Each of these different snow lines — for water, carbon dioxide, methane and carbon monoxide — may be linked to the formation of particular kinds of planets . Around a Sun-like star in a planetary system like our own, the water snow line would correspond to a distance between the orbits of Mars and Jupiter, and the carbon monoxide snow line would correspond to the orbit of Neptune.
The snow line spotted by ALMA is the first glimpse of the carbon monoxide snow line, around TW Hydrae, a young star 175 light-years away from Earth. Astronomers believe this budding planetary system shares many of the same characteristics of the Solar System when it was just a few million years old.
“ALMA has given us the first real picture of a snow line around a young star, which is extremely exciting because of what it tells us about the very early period in the history of the Solar System,” said Chunhua “Charlie” Qi (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA) one of the two lead authors of the paper. “We can now see previously hidden details about the frozen outer reaches of another planetary system similar to our own.”
But the presence of a carbon monoxide snow line could have greater consequences than just the formation of planets. Carbon monoxide ice is needed to form methanol, which is a building block of the more complex organic molecules that are essential for life. If comets ferried these molecules to newly forming Earth-like planets, these planets would then be equipped with the ingredients necessary for life.
Before now, snow lines had never been imaged directly because they always form in the relatively narrow central plane of a protoplanetary disc, so their precise location and extent could not be determined. Above and below the narrow region where snow lines exist, the star’s radiation prevents ice formation. The dust and gas concentration in the central plane is necessary to insulate the area from the radiation so that carbon monoxide and other gases can cool and freeze.
This team of astronomers succeeded in peering inside this disc to where the snow has formed with the help of a clever trick. Instead of looking for the snow — as it cannot be observed directly — they searched for a molecule known as diazenylium (N2H+), which shines brightly in the millimetre portion of the spectrum, and so is a perfect target for a telescope such as ALMA. The fragile molecule is easily destroyed in the presence of carbon monoxide gas, so would only appear in detectable amounts in regions where carbon monoxide had become snow and could no longer destroy it. In essence, the key to finding carbon monoxide snow lies in finding diazenylium.
ALMA’s unique sensitivity and resolution has allowed the astronomers to trace the presence and distribution of diazenylium and find a clearly defined boundary approximately 30 astronomical units from the star (30 times the distance between the Earth and the Sun). This gives, in effect, a negative image of the carbon monoxide snow in the disc surrounding TW Hydrae, which can be used to see the carbon monoxide snow line precisely where theory predicts it should be — the inner rim of the diazenylium ring.
“For these observations we used only 26 of ALMA’s eventual full complement of 66 antennas. Indications of snow lines around other stars are already showing up in other ALMA observations, and we are convinced that future observations with the full array will reveal many more of these and provide further, exciting insights into the formation and evolution of planets. Just wait and see,” concludes Michiel Hogerheijde from Leiden Observatory, the Netherlands.
 For instance dry rocky planets form on the inner side of the water snow line (nearest the star), where only dust can exist. At the other extreme are the icy giant planets which form beyond the carbon monoxide snow line.
The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Southern Observatory (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.
This research was presented in a paper appearing in the 18 July 2013 issue of Science Express.
The team is composed of C. Qi (Harvard-Smithsonian Center for Astrophysics, USA), K. I. Öberg (Departments of Chemistry and Astronomy, University of Virginia, USA), D. J. Wilner (Harvard-Smithsonian Center for Astrophysics, USA), P. d’Alessio (Centro de Radioastronomía y Astroﬁsica, Universidad Nacional Autónoma de Mexico, Mexico), E. Bergin (Department of Astronomy, University of Michigan, USA), S. M. Andrews (Harvard-Smithsonian Center for Astrophysics, USA), G. A. Blake (Division of Geological and Planetary Sciences, California Institute of Technology, USA), M. R. Hogerheijde (Leiden Observatory, Leiden University, Netherlands) and E. F. van Dishoeck (Max Planck Institute for Extraterrestrial Physics, Germany).
Qi and Öberg were joint lead authors of this work.
ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning the 39-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.
For better or worse citizen science has become a fashionable term, but what is it and why do people like it? Citizen Science is a big component in a larger movement of public participation and engagement. There are makers and hackers everywhere and participation in science feels like it is increasing in general. This is great, and means citizen science is of growing importance.