ESO released a beautiful image today of M83, a classic spiral galaxy. The image was 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 the combination of the huge mirror of the VLT, the large field of view and great sensitivity of the HAWK –I and the superb observing conditions at ESO’s Paranal Observatory makes this one of the sharpest and most detailed pictures of Messier 83 ever taken from the ground. M83 is perhaps a mirror to how our own Milky Way galaxy looks, could we step outside and take a look.
Messier 83 is located about 15 million light-years away in the constellation of Hydra. It is famous for its many supernovae: over the last century, six supernovae have been observed in Messier 83 — a record number that is matched by only one other galaxy. Even without supernovae, Messier 83 is one of the brightest nearby galaxies, visible using just binoculars.
Check out this article by our resident astronomer Tammy Plotner to find out how you can spot M83 in the night sky.
Galaxy Cluster Abell 315 as seen by ESO's 2.2 meter telescope at La Silla. Credit: ESO/J. Dietrich
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In an image akin to the Hubble Deep Field, ESO’s La Silla Observatory in Chile stared at a patch of sky about as big as a full Moon and observed thousands of distant galaxies. The Wide Field Imager on ESO’s 2.2 meter telescope zeroed in on a large group of galaxies that are part of the massive galaxy cluster known as Abell 315. But there’s more in this image—including relatively close asteroids that show up as blue, green or red trails, which lie in the main asteroid belt, located between the orbits of Mars and Jupiter. Also, invisible dark matter is revealed in this image through its gravitational effects, noticeably visible on this galaxy cluster.
Of course, not all the galaxies seen here are the same distance from us. Some are relatively close, as it is possible to distinguish their spiral arms or elliptical halos if you zoom in on this larger image, especially in the upper part of the image. The more distant galaxies appear just like faint of blobs — their light has traveled through the Universe for eight billion years or more before reaching Earth.
The concentration of about a hundred yellowish galaxies is the Abell 315 galaxy cluster. The cluster is located in the constellation of Cetus (the Whale).
The galaxies in these clusters contribute to only ten percent of the mass, with hot gas in between galaxies accounting for another ten percent. The remaining 80 percent is made of dark matter that lies in between the galaxies.
We know the dark matter is there because of its effects: the enormous mass of a galaxy cluster acts on the light from galaxies behind the cluster like a cosmic magnifying glass, bending the trajectory of the light and thus making the galaxies appear slightly distorted. By observing and analyzing the twisted shapes of these background galaxies, astronomers can infer the total mass of the cluster responsible for the distortion, even when this mass is mostly invisible. However, this effect is usually tiny, and it is necessary to measure it over a huge number of galaxies to obtain significant results. In the case of Abell 315, the shapes of almost 10,000 faint galaxies in this image were studied in order to estimate the total mass of the cluster, which amounts to over a hundred thousand billion times the mass of our Sun.
Artist’s impression of how Triton, Neptune’s largest moon, might look from high above its surface. Credit: ESO/L. Calçada
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If you’re planning a trip to Neptune’s moon Triton, you’ll want to head to the southern hemisphere where it’s now just past mid-summer. Yes, distant Triton actually does have seasons, astronomers at ESO’s Very Large Telescope recently determined. “We have found real evidence that the Sun still makes its presence felt on Triton, even from so far away,” said astronomer Emmanuel Lellouch in an ESO press release. “This icy moon actually has seasons just as we do on Earth, but they change far more slowly.” According to the first ever infrared analysis of Triton’s atmosphere, the seasons last about 40 Earth years. But while summer is in full swing in Triton’s southern hemisphere, there’s no need to pack your bikini. The average surface temperature is about minus 235 degrees Celsius.
Oh, and you’ll also want to bring along a little breathable air. The ESO team also – unexpectedly – discovered carbon monoxide in Triton’s thin atmosphere, mixed in with methane and nitrogen.
The astronomer’s observations revealed that Triton’s thin atmosphere varies seasonally, thickening when warmed. When the distant sun’s rays hits Triton at their best summer angle, a thin layer of frozen nitrogen, methane, and carbon monoxide on Triton’s surface sublimates into gas, thickening the icy atmosphere as the season progresses during Neptune’s 165-year orbit around the Sun. Triton passed the southern summer solstice in 2000. Voyager 2's view of Triton. Credit: NASA
So, while this action increases the thickness of the atmosphere, thus increasing the atmospheric pressure, you’ll still need a pressure suit as well for your visit. Based on the amount of gas measured, Lellouch and his colleagues estimate that Triton’s atmospheric pressure may have risen by a factor of four compared to the measurements made by Voyager 2 in 1989, when it was still spring on the giant moon. The Voyager data indicated the atmosphere of nitrogen and methane had a pressure of 14 microbars, 70,000 times less dense than the atmosphere on Earth. The data from ESO shows the atmospheric pressure is now between 40 and 65 microbars — 20,000 times less than on Earth.
Carbon monoxide was known to be present as ice on the surface, but Lellouch and his team discovered that Triton’s upper surface layer is enriched with carbon monoxide ice by about a factor of ten compared to the deeper layers, and that it is this upper “film” that feeds the atmosphere. While the majority of Triton’s atmosphere is nitrogen (much like on Earth), the methane in the atmosphere, first detected by Voyager 2, and only now confirmed in this study from Earth, plays an important role as well.
“Climate and atmospheric models of Triton have to be revisited now, now that we have found carbon monoxide and re-measured the methane,” said co-author Catherine de Bergh. The team’s results are published in Astronomy & Astrophysics
If we could actually visit Triton, it would likely be a very interesting destination as we know it has geologic activity and a changing surface – plus its unique retrograde motion would offer a unique view of the solar system.
While Triton is the seventh largest moon in our solar system, its distance and position from Earth makes it difficult to observe, and ground-based observations since Voyager 2 have been limited. Observations of stellar occultations (a phenomenon that occurs when a Solar System body passes in front of a star and blocks its light) indicated that Triton’s surface pressure was increasing in the 1990’s. But a new instrument on the VLT, the Cryogenic High-Resolution Infrared Echelle Spectrograph (CRIRES) has provided the chance to perform a more detailed study of Triton’s atmosphere. “We needed the sensitivity and capability of CRIRES to take very detailed spectra to look at the very tenuous atmosphere,” said co-author Ulli Käufl.
These observations are just the beginning for the CRIRES instrument, which will be extremely helpful in studying other distant bodies in our solar system, such as Pluto and other Kuiper Belt Objects. Pluto is often considered a cousin of Triton with similar conditions, and in the light of the carbon monoxide discovery on Triton, astronomers are racing to find this chemical on the even more distant Pluto.
Astronomers have long known that many surveys of distant galaxies miss 90% of their targets, but they didn’t know why. Now, astronomers have determined that a large fraction of galaxies whose light took 10 billion years to reach us have gone undiscovered. This was found with an extremely deep survey using two of the four giant 8.2-meter telescopes that make up ESO’s Very Large Telescope (VLT) and a unique custom-built filter. The survey also helped uncover some of the faintest galaxies ever found at this early stage of the Universe.
Astronomers frequently use the strong, characteristic “fingerprint” of light emitted by hydrogen known as the Lyman-alpha line, to probe the amount of stars formed in the very distant Universe Yet there have long been suspicions that many distant galaxies go unnoticed in these surveys. A new VLT survey demonstrates for the first time that this is exactly what is happening. Most of the Lyman-alpha light is trapped within the galaxy that emits it, and 90% of galaxies do not show up in Lyman-alpha surveys.
“Astronomers always knew they were missing some fraction of the galaxies in Lyman-alpha surveys,” explains Matthew Hayes, the lead author of the paper, published this week in Nature, “but for the first time we now have a measurement. The number of missed galaxies is substantial.”
To figure out how much of the total luminosity was missed, Hayes and his team used the FORS camera at the VLT and a custom-built narrowband filter to measure this Lyman-alpha light, following the methodology of standard Lyman-alpha surveys. Then, using the new HAWK-I camera, attached to another VLT Unit Telescope, they surveyed the same area of space for light emitted at a different wavelength, also by glowing hydrogen, and known as the H-alpha line. They specifically looked at galaxies whose light has been traveling for 10 billion years (redshift 2.2), in a well-studied area of the sky, known as the GOODS-South field.
“This is the first time we have observed a patch of the sky so deeply in light coming from hydrogen at these two very specific wavelengths, and this proved crucial,” said team member Goran Ostlin. The survey was extremely deep, and uncovered some of the faintest galaxies known at this early epoch in the life of the Universe. The astronomers could thereby conclude that traditional surveys done using Lyman-alpha only see a tiny part of the total light that is produced, since most of the Lyman-alpha photons are destroyed by interaction with the interstellar clouds of gas and dust. This effect is dramatically more significant for Lyman-alpha than for H-alpha light. As a result, many galaxies, a proportion as high as 90%, go unseen by these surveys. “If there are ten galaxies seen, there could be a hundred there,” Hayes said.
Different observational methods, targeting the light emitted at different wavelengths, will always lead to a view of the Universe that is only partially complete. The results of this survey issue a stark warning for cosmologists, as the strong Lyman-alpha signature becomes increasingly relied upon in examining the very first galaxies to form in the history of the Universe. “Now that we know how much light we’ve been missing, we can start to create far more accurate representations of the cosmos, understanding better how quickly stars have formed at different times in the life of the Universe,” said co-author Miguel Mas-Hesse.
The breakthrough was made possible thanks to the unique camera used. HAWK-I, which saw first light in 2007, is a state-of-the-art instrument. “There are only a few other cameras with a wider field of view than HAWK-I, and they are on telescopes less than half the size of the VLT. So only VLT/HAWK-I, really, is capable of efficiently finding galaxies this faint at these distances,” said team member Daniel Schaerer.
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This new image from the ESO telescope in Chile shows what looks like a Chinese dragon in the sky. But really, it is NGC 5189 an S-shaped planetary nebula adorned with red and green cosmic fireworks. This dragon isn’t breathing fire – the colorful “smoke” is a signal that a star is dying.
At the end of its life, a star with a mass less than eight times that of the Sun will blow its outer layers away, giving rise to a planetary nebula. Some of these stellar puffballs are almost round, resembling huge soap bubbles or giant planets (hence the name), but others, such as NGC 5189 are more intricate.
In particular, this planetary nebula exhibits a curious “S”-shaped profile, with a central bar that is most likely the projection of an inner ring of gas discharged by the star, seen edge on. The details of the physical processes producing such a complex symmetry from a simple, spherical star are still the object of astronomical controversy. One possibility is that the star has a very close (but unseen) companion. Over time the orbits drift due to precession and this could result in the complex curves on the opposite sides of the star visible in this image.
This image has been taken with the New Technology Telescope at ESO’s La Silla Observatory in Chile, using the now decommissioned EMMI instrument. It is a combination of exposures taken through different narrowband filters, each designed to catch only the light coming from the glow of a given chemical element, namely hydrogen, oxygen and nitrogen.
New image of NGC 346, the Small Magellanic Cloud. Credit: ESO
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It’s not Earth, Wind and Fire*, but light, wind and fire in this dramatic new image of the Small Magellanic Cloud (NGC 346) that will make you want to Keep Your Head to the Sky**. The light, wind and heat given off by massive, Mighty Mighty ** Shinging Star(s)** have dispersed the glowing gas within and around this star cluster, forming a surrounding wispy nebular structure that looks like a cobweb. As yet more stars form from lose matter in the area, they will ignite, scattering leftover dust and gas, carving out great ripples and altering the face of this lustrous object. But, That’s the Way of the World** in this open cluster of stars, that we just Can’t Hide Love** for.
The nebula containing this clutch of bright stars can really Sparkle **. It is known as an emission nebula, meaning that gas within it has been heated up by stars until the gas emits its own light, just like the neon gas used in electric store signs.
This image was taken with the Wide Field Imager (WFI) instrument at the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile. Images like this help astronomers Turn It Into Something Good** by helping to chronicle star birth and evolution, while offering glimpses of how stellar development influences the appearance of the cosmic environment over time.
If you want more information about this image, you can Let Your Feelings Show** by visiting the ESO website.
*The band Earth, Wind and Fire is sometimes known as Elements of the Universe
** indicates song titles recorded by Earth, Wind and Fire
The Fornax dwarf galaxy is one of our Milky Way’s neighbouring dwarf galaxies and a good example of what an early dwarf galaxy might have been like. This image was composed from data from the Digitized Sky Survey 2. Credit: ESO
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Astronomer sleuths have solved a cosmic mystery by finding primitive stars that have been stealthily concealed. Using ESO’s Very Large Telescope a group of astronomers have uncovered an important astrophysical puzzle concerning the oldest stars in our galactic neighborhood — which is crucial for our understanding of the earliest stars in the Universe. . “We have, in effect, found a flaw in the forensic methods used until now,” said Else Starkenburg, lead author of a paper reporting the new findings. “Our improved approach allows us to uncover the primitive stars hidden among all the other, more common stars.”
Primitive stars are thought to have formed from material forged shortly after the Big Bang, 13.7 billion years ago. They typically have less than one thousandth the amount of chemical elements heavier than hydrogen and helium found in the Sun and are called “extremely metal-poor stars.” They belong to one of the first generations of stars in the nearby Universe. Such stars are extremely rare and mainly observed in the Milky Way. The Sculptor dwarf galaxy is one of our Milky Way’s neighbouring dwarf galaxies. Credit: ESO/Digitized Sky Survey 2
Cosmologists think that larger galaxies like the Milky Way formed from the merger of smaller galaxies. Our Milky Way’s population of extremely metal-poor or “primitive” stars should already have been present in the dwarf galaxies from which it formed, and similar populations should be present in other dwarf galaxies. “So far, evidence for them has been scarce,” said co-author Giuseppina Battaglia. “Large surveys conducted in the last few years kept showing that the most ancient populations of stars in the Milky Way and dwarf galaxies did not match, which was not at all expected from cosmological models.”
Element abundances are measured from spectra, which provide the chemical fingerprints of stars. The Dwarf galaxies Abundances and Radial-velocities Team used the FLAMES instrument on ESO’s Very Large Telescope to measure the spectra of over 2000 individual giant stars in four of our galactic neighbors, the Fornax, Sculptor, Sextans and Carina dwarf galaxies. Since the dwarf galaxies are typically 300,000 light years away — which is about three times the size of our Milky Way — only strong features in the spectrum could be measured, like a vague, smeared fingerprint. The team found that none of their large collection of spectral fingerprints actually seemed to belong to the class of stars they were after, the rare, extremely metal-poor stars found in the Milky Way.
The team of astronomers around Starkenburg has now shed new light on the problem through careful comparison of spectra to computer-based models. They found that only subtle differences distinguish the chemical fingerprint of a normal metal-poor star from that of an extremely metal-poor star, explaining why previous methods did not succeed in making the identification.
The astronomers also confirmed the almost pristine status of several extremely metal-poor stars thanks to much more detailed spectra obtained with the UVES instrument on ESO’s Very Large Telescope. “Compared to the vague fingerprints we had before, this would be as if we looked at the fingerprint through a microscope,” explains team member Vanessa Hill. “Unfortunately, just a small number of stars can be observed this way because it is very time consuming.”
“Among the new extremely metal-poor stars discovered in these dwarf galaxies, three have a relative amount of heavy chemical elements between only 1/3000 and 1/10 000 of what is observed in our Sun, including the current record holder of the most primitive star found outside the Milky Way,” said team member Martin Tafelmeyer.
“Not only has our work revealed some of the very interesting, first stars in these galaxies, but it also provides a new, powerful technique to uncover more such stars,” concluded Starkenburg. “From now on there is no place left to hide!”
Artist impression of the Extremely Large Telescope. Credit: ESO
Question: Where are the night skies always dark, cloud-free 360 days a year, bone-dry, and orbiting 3.5 km above sea level?
Answer: Armazones Mountain, Atacama desert, Chile.
Question: Who wants to go live there?
Answer: The European Extremely-Large Telescope (E-ELT)!
“We are talking about the biggest telescope in the world, the biggest for a long time to come. That means we have to choose the best spot. Chile has a superb location. It’s the best in the world, there’s no doubt,” the European Southern Observatory’s astronomer, Massimo Tarenghi, told AFP. He is one of four astronomers – two Chileans, an Italian (Tarenghi) and a German – who were in the desert this week to evaluate its suitability compared to the main other contender: the Spanish isle of La Palma in the Canary Islands off western Africa.
The European Southern Observatory (ESO), an intergovernmental astronomical research agency that already has three facilities operating in the Atacama desert, including the Very Large Telescope array in the town of Paranal which is currently considered Europe’s foremost observatory.
Work on the E-ELT is to begin in December 2011 and cost 90 million euros (120 million dollars) … once a decision is made on the site, which will be as early as March this year.
When complete, the E-ELT will be “the world’s biggest eye on the sky,” according to the ESO, which hopes it will “address many of the most pressing unsolved questions in astronomy.”
The E-ELT is likely to be as revolutionary in the field of astronomy as Galileo’s telescope 400 years ago that determined that the Sun, and not the Earth, was the center of our universe, according to the European agency based in Munich, Germany. The German astronomer in Chile, Wolfgang Gieren, waxed happily about the possibilities of the future telescope. “In no more than 15 years we could have the first good-resolution spectra of planets outside our universe that are the same size of Earth and see if we can detect signs of life,” he said.
One of the Chilean astronomers, Mario Harmuy, said the Armazones provided an ideal location. “Several things come together here. The cold Humboldt Current, which passes by Chile’s coast, means that there is a high pressure center in the Pacific that deflects high clouds and prevents cover over this part of the continent,” he said. “To the east, the high Andes mountains prevent humidity from moving in from the Atlantic with clouds. The higher you are, the less humidity there is, and thus the light from the stars go through less of the atmosphere and is distorted less when it hits the telescope.” To boot, the Chilean location is free of the storms that hit the Canary Islands and the Sahara, he said.
Tarneghi added that the ESO’s existing Paranal observatory nearby also meant that much of the ground infrastructure was already in place.
Chile’s government was equally enthusiastic about hosting the E-ELT. Gabriel Rodriguez, in charge of the foreign ministry’s science and technology division, said Chile was ready to cede the 600 hectares (1,500 acres) needed for the project. The government is to submit its offer to the ESO next Monday, with a decision expected early March.
The Italian astronomer cautioned that despite Chile’s obvious advantages, the tender had to be weighed carefully for all its aspects. “Neither any of us nor the ESO know what the final decision will be. We need to receive the Chilean and Spanish proposals and evaluate factors of operation, work and production costs,” Tarenghi said.
The other Chilean astronomer, Maria Teresa Ruiz, remained fired up at the potential of the new instrument. The “surface area of this telescope is bigger than all the others in Chile combined, which will allow us to explore things in the universe that we can’t even imagine today,” she said.
Orion from the VISTA infrared telescope. Credit: ESO
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Oh-oh-oh Orion! The new VISTA (Visible and Infrared Survey Telescope for Astronomy) infrared survey telescope has used its huge field of view to show the full splendor of the Orion Nebula. With its infrared eyes, it has peered deeply into dusty regions that are normally hidden to expose the curious behavior of the very active young stars buried there.
VISTA is the latest addition to ESO’s Paranal Observatory. It is the largest survey telescope in the world and is dedicated to mapping the sky at infrared wavelengths. The large (4.1-metre) mirror, wide field of view and very sensitive detectors make VISTA a unique instrument. This dramatic new image of the Orion Nebula illustrates VISTA’s remarkable powers.
The Orion Nebula is about 1,350 light-years from Earth. Although spectacular when seen through an ordinary telescope, what can be seen using visible light is only a small part of a cloud of gas in which stars are forming. Most of the action is deeply embedded in dust clouds and to see what is really happening astronomers need to use telescopes with detectors sensitive to the longer wavelength radiation that can penetrate the dust. VISTA has imaged the Orion Nebula at wavelengths about twice as long as can be detected by the human eye.
Four highlights of the new VISTA image of Orion. Credit: ESO
On the upper-left, the central region of VISTA’s view of the Orion Nebula is shown, centered on the four dazzling stars of the Trapezium. A rich cluster of young stars can be seen here that is invisible in normal, visible light images. In the lower-right panel the part of the nebula to the north of the center is shown. Here there are many young stars embedded in the dust clouds that are only apparent because their infrared glow can penetrate the dust and be detected by the VISTA camera. Many outflows, jets and other interactions from young stars are apparent, seen in the infrared glow from molecular hydrogen and showing up as red blobs. On the upper-right, a region to the west of center is shown. Here the fierce ultraviolet light from the Trapezium is sculpting the gas clouds into curious wavy shapes. A distant edge-on spiral galaxy is also seen shining right through the nebula. At the lower-left a region south of the center is shown. Each extract covers a region of sky about nine arcminutes across.
All these features are of great interest to astronomers studying the birth and youth of stars.
The stellar nursery, NGC 3603. Credit: ESO. Click for access to larger versions.
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This magnificent image of the giant stellar nursery surrounding NGC 3603 was taken by the Very Large Telescope at Cerro Paranal, Chile. This nebula is a starburst region, a huge star-making factory where stars form frantically from the nebula’s billowing clouds of gas and dust. It is located 22,000 light-years away from the Sun, and is the closest region of this kind known in our galaxy. Thousands of stars inhabit this region, with most having masses similar to that of our sun. But other stars are some of the most spectacular and massive stars around. In fact, one star, NGC 3603 A1, is the most massive star ever “weighed.” Several blue supergiant stars crowd into a volume of less than a cubic light-year, along with three so-called Wolf-Rayet stars — extremely bright and massive stars that will do the supernova gig relatively soon. The Bad Astronomer tells it way better than I, so go check out his gigantisized blog post.
