Picture of the Week

31 December 2012

Whirling Southern Star Trails over ALMA

Babak Tafreshi, one of the ESO Photo Ambassadors, has captured the antennas of the Atacama Large Millimeter/submillimeter Array (ALMA) under the southern sky in another breathtaking image.

The dramatic whorls of stars in the sky are reminiscent of van Gogh’s Starry Night, or — for science fiction fans — perhaps the view from a spacecraft about to enter hyperspace. In reality, though, they show the rotation of the Earth, revealed by the photograph’s long exposure. In the southern hemisphere, as the Earth turns, the stars appear to move in circles around the south celestial pole, which lies in the dim constellation of Octans (The Octant), between the more famous Southern Cross and the Magellanic Clouds. With a long enough exposure, the stars mark out circular trails as they move.

The photograph was taken on the Chajnantor Plateau, at an altitude of 5000 metres in the Chilean Andes. This is the site of the ALMA telescope, whose antennas can be seen in the foreground. ALMA is the most powerful telescope for observing the cool Universe — molecular gas and dust, as well as the relic radiation of the Big Bang. When ALMA construction is complete in 2013, the telescope will have 54 of these 12-metre-diameter antennas, and twelve 7-metre antennas. However, early scientific observations with a partial array already began in 2011. Even though it is not fully constructed, the telescope is already producing outstanding results, outperforming all other telescopes of its kind. Some of the antennas are blurred in the photograph, as the telescope was in operation and moving during the shot.

ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), 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.

Links


24 December 2012

ALMA’s Solitude

This panoramic view of the Chajnantor Plateau shows the site of the Atacama Large Millimeter/submillimeter Array (ALMA), taken from near the peak of Cerro Chico. Babak Tafreshi, an ESO Photo Ambassador, has succeeded in capturing the feeling of solitude experienced at the ALMA site, 5000 metres above sea level in the Chilean Andes. Light and shadow paint the landscape, enhancing the otherworldly appearance of the terrain. In the foreground of the image, clustered ALMA antennas look like a crowd of strange, robotic visitors to the plateau. When the telescope is completed in 2013, there will be a total of 66 such antennas in the array, operating together.

ALMA is already revolutionising how astronomers study the Universe at millimetre and submillimetre wavelengths. Even with a partial array of antennas, ALMA is more powerful than any previous telescope at these wavelengths, giving astronomers an unprecedented capability to study the cool Universe — molecular gas and dust as well as the relic radiation of the Big Bang. ALMA studies the building blocks of stars, planetary systems, galaxies, and life itself. By providing scientists with detailed images of stars and planets being born in gas clouds near the Solar System, and detecting distant galaxies forming at the edge of the observable Universe, which we see as they were roughly ten billion years ago, it will let astronomers address some of the deepest questions of our cosmic origins.

ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), 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.

Links


17 December 2012

Paranal and the Shadow of the Earth

ESO Photo Ambassador, Babak Tafreshi has taken another outstanding panoramic photograph of ESO’s Paranal Observatory.

In the foreground is the dramatic, mountainous landscape of the Atacama Desert. On the left, on the highest peak, is the ESO Very Large Telescope (VLT), and in front of it, on a slightly lower peak, is the VISTA telescope (Visible and Infrared Survey Telescope for Astronomy).

In the background, the sunrise colours Paranal’s sky with a beautiful pastel palette. Extending beyond the horizon, the sea of clouds over the Pacific Ocean — which lies only 12 kilometres from Paranal — is visible.

Above the horizon, where the sea of clouds meets the sky, a dark band can be seen. This dark band is the Earth’s shadow, cast by the planet onto its atmosphere. This phenomenon can sometimes be seen around the times of sunset and sunrise, if the sky is clear and the horizon is unobstructed — conditions that are certainly met in Paranal Observatory. Above the Earth’s shadow is a pinkish glow known as the Belt of Venus. It is caused by light from the rising (in this case) or setting Sun being scattered by the Earth’s atmosphere.

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10 December 2012

The Stars Streak Overhead

Although this image might at first look like abstract modern art, it is in fact the result of a long camera exposure of the night sky over the Chajnantor Plateau in the Chilean Andes. As the Earth rotates towards another day, the stars of the Milky Way above the desert stretch into colourful streaks. The high-tech telescope in the foreground, meanwhile, takes on a dreamlike quality.

This mesmerising photo was taken 5000 metres above sea level on the Chajnantor Plateau, home of the Atacama Pathfinder Experiment (APEX) telescope, which is seen here. APEX is a 12-metre-diameter telescope which collects light with wavelengths in the millimetre and submillimetre range. Astronomers use APEX to study objects ranging from the cold clouds of gas and cosmic dust where new stars are being born, to some of the earliest and most distant galaxies in the Universe.

APEX is a pathfinder for the Atacama Large  Millimeter/submillimeter Array (ALMA), a revolutionary telescope that ESO, together with its international partners, is building and operating, also on the Chajnantor Plateau. When ALMA is completed in 2013, it will be an array of 54 antennas with 12-metre diameters, and an additional 12 antennas with 7-metre diameters. The two telescopes are complementary: thanks to its larger field of view, APEX can find many targets across wide areas of sky, which ALMA will study in great detail due to its far higher angular resolution. APEX and ALMA are both important tools to help astronomers find out more about the workings of our Universe, such as the formation of the stars seen wheeling overhead in this image.

ESO Photo Ambassador Babak Tafreshi took this picture. He is also founder of The World At Night, a programme to create and exhibit a collection of stunning photographs and time-lapse videos of the world’s most beautiful and historic sites against a nighttime backdrop of stars, planets and celestial events.

APEX is a collaboration between the Max Planck Institute for Radio Astronomy (MPIfR), the Onsala Space Observatory (OSO) and ESO. Operation of APEX at Chajnantor is entrusted to ESO. ALMA is an international astronomy facility, and a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ESO is the European partner in ALMA.

Links


26 November 2012

Two Planet-hunters Snapped at La Silla

For centuries, philosophers and scientists have wondered about the possibility of habitable planets outside the Solar System. Today, this idea is more than speculation: many hundreds of exoplanets have been discovered over the last couple of decades, by astronomers all over the world. Various different techniques are used in this search for new worlds. In this unusual photograph, telescopes using two of these methods, the ESO 3.6-metre telescope with the HARPS spectrograph, and the space telescope CoRoT, have been captured in the same shot. The photograph was taken by Alexandre Santerne, an astronomer who studies exoplanets himself.

The High Accuracy Radial velocity Planetary Search (HARPS) spectrograph, the world’s foremost exoplanet hunter, is an instrument on ESO’s 3.6-metre telescope. The open dome of this telescope can be seen on the left of this image, behind the angular enclosure of the New Technology Telescope. HARPS finds exoplanets by detecting small changes in the motion of a star as it wobbles slightly under the gravitational pull of the orbiting planet. This is known as the radial velocity technique for finding exoplanets.

The faint trail of light high in the sky in this 20-second exposure is not a meteor but CoRoT, the Convection Rotation and planetary Transits space telescope. CoRoT searches for planets by looking for the dimming of light from a star which occurs when a planet passes in front of it — the transit method. The space telescope’s location above the Earth’s atmosphere improves the accuracy of its observations by removing the twinkling of stars. Potential planets found by the transit method are confirmed using complementary techniques such as the radial velocity method. Indeed, on very the night that this photograph was taken, HARPS was being used to follow up exoplanet candidates detected by CoRoT!

In November 2012, CoRoT unfortunately suffered a computer problem, meaning that — although it is still functioning — it can no longer retrieve data from its telescope (see the news on the CoRoT website, or for example this Nature News article). The CoRoT team have not given up though, and are working to revive the systems. Whether or not CoRoT can be revived, there is certainly no doubt that the mission has already been a great success! The spacecraft has doubled its originally planned mission lifetime, and was the first spacecraft to discover an exoplanet using the transit method. CoRoT has made great contributions, both to the search for exoplanets, and to the study of the interiors of stars through the field of asteroseismology.

The search for exoplanets helps us understand our own planetary system, and may be the first step towards finding life beyond Earth. HARPS and CoRoT are just two of the many exciting instruments developed to assist astronomers with this search.

Alexandre 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. In 2012, as part of ESO’s 50th anniversary year, we are also welcoming your historical ESO-related images. Since submitting the photo, Alexandre has also become an ESO Photo Ambassador.

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19 November 2012

APEX's Icy Companions

The Atacama Pathfinder Experiment (APEX) telescope — captured in this dramatic image taken by ESO Photo Ambassador Babak Tafreshi — is one of the tools used by ESO to peer beyond the realm of visible light. It is located on the Chajnantor Plateau at an altitude of 5000 metres.

Clusters of white penitentes can be seen in the foreground of the photograph. The penitentes (Spanish for penitents) are a curious natural phenomenon found in high altitude regions, typically more than 4000 metres above sea level. They are thin spikes of hardened snow or ice, with their blades pointing towards the Sun, attaining heights from a few centimetres up to several metres.

APEX is a 12-metre-diameter telescope that observes light at millimetre and submillimetre wavelengths. Astronomers observing with APEX can see phenomena which would be invisible at shorter wavelengths. The telescope enables them to study molecular clouds — the dense regions of gas and cosmic dust where new stars are being born — which are dark and obscured by dust in visible or infrared light, but which glow brightly at these relatively longer wavelengths. Astronomers use this light to study their chemical and physical conditions. This wavelength range is also ideal for studying some of the earliest and most distant galaxies in the Universe.

Just visible in the night sky above and to the left of APEX are, respectively, the faint smudges of the Small and Large Magellanic Clouds, neighbouring galaxies of our own Milky Way galaxy. The plane of the Milky Way itself can be seen as a hazy band across the sky, most prominently over the APEX control building on the right. Dark patches in the band are regions where light from distant stars is blocked by interstellar dust. Hidden behind these dark dust lanes, the centre of the Milky Way lies at a distance of about 27 000 light-years. Telescopes such as APEX are a crucial tool for astronomers to peer through the dust and study the centre of our galaxy in detail.

APEX is a collaboration between the Max Planck Institute for Radio Astronomy (MPIfR), the Onsala Space Observatory (OSO) and ESO. Operation of APEX at Chajnantor is entrusted to ESO.

Links


12 November 2012

One Picture, Many Stories

ESO Photo Ambassador, Babak Tafreshi has captured an outstanding image of the sky over ESO’s Paranal Observatory, with a treasury of deep-sky objects.

The most obvious of these is the Carina Nebula, glowing intensely red in the middle of the image.  The Carina Nebula lies in the constellation of Carina (The Keel), about 7500 light-years from Earth. This cloud of glowing gas and dust is the brightest nebula in the sky and contains several of the brightest and most massive stars known in the Milky Way, such as Eta Carinae. The Carina Nebula is a perfect test-bed for astronomers to unveil the mysteries of the violent birth and death of massive stars. For some beautiful recent images of the Carina Nebula from ESO, see eso1208, eso1145, and eso1031.

Below the Carina Nebula, we see the Wishing Well Cluster (NGC 3532). This open cluster of young stars was named because, through a telescope’s eyepiece, it looks like a handful of silver coins twinkling at the bottom of a wishing well. Further to the right, we find the Lambda Centauri Nebula (IC 2944), a cloud of glowing hydrogen and newborn stars which is sometimes nicknamed the Running Chicken Nebula, from a bird-like shape that some people see in its brightest region (see eso1135). Above this nebula and slightly to the left we find the Southern Pleiades (IC 2632), an open cluster of stars that is similar to its more familiar northern namesake.

In the foreground, we see three of the four Auxiliary Telescopes (ATs) of the Very Large Telescope Interferometer (VLTI). Using the VLTI, the ATs — or the VLT’s 8.2-metre Unit Telescopes — can be used together as a single giant telescope which can see finer details than would be possible with the individual telescopes. The VLTI has been used for a broad range of research including the study of circumstellar discs around young stellar objects and of active galactic nuclei, one of the most energetic and mysterious phenomena in the Universe.

Links


29 October 2012

A Place to Unveil the Mysteries of the Cold Universe

This beautiful panoramic picture taken by Babak Tafreshi, an ESO Photo Ambassador, shows the last rays of sunlight bathing the Chajnantor Plateau in Chile’s Atacama region. The plateau is the home of the Atacama Pathfinder Experiment (APEX) telescope, which can be seen on the left of the panorama. From this remote place on Earth, 5000 metres above sea level, APEX studies the “cold Universe”.

APEX is a 12-metre-diameter telescope that observes light at millimetre and submillimetre wavelengths. Astronomers observing with APEX can see phenomena which would be invisible at shorter wavelengths. The telescope enables them to study molecular clouds — the dense regions of gas and cosmic dust where new stars are being born — which are dark and obscured by dust in visible or infrared light, but which glow brightly at these relatively longer wavelengths. Astronomers use this light to study the chemical and physical conditions in the clouds. This wavelength range is also ideal for studying some of the earliest and most distant galaxies in the Universe.

Since it began operating in 2005, APEX has produced many important science results. For example, APEX teamed up with ESO’s Very Large Telescope to detect matter being torn apart by the black hole at the centre of the Milky Way (eso0841), a result counted among the ESO Top 10 Astronomical Discoveries.

Clusters of white penitentes can be seen on the ground around APEX. The penitentes (Spanish for penitents) are a curious natural phenomenon found in high-altitude regions, typically more than 4000 metres above sea level. They are thin spikes of hardened snow or ice, with their blades pointing towards the Sun, attaining heights from a few centimetres up to several metres.

APEX is a collaboration between the Max Planck Institute for Radio Astronomy (MPIfR), the Onsala Space Observatory (OSO) and ESO. Operation of APEX at Chajnantor is entrusted to ESO.

APEX’s 12-metre dish is based on a prototype antenna for another observatory on Chajnantor, the Atacama Large Millimeter/submillimeter Array (ALMA). ALMA will have an array of fifty-four 12-metre antennas and twelve 7-metre antennas, when it is completed in 2013. ESO is the European partner in this international astronomy facility, which is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile.

Links


15 October 2012

From Cosmic Spare Tyre to Ethereal Blossom

IC 5148 is a beautiful planetary nebula located some 3000 light-years away in the constellation of Grus (The Crane). The nebula has a diameter of a couple of light-years, and it is still growing at over 50 kilometres per second — one of the fastest expanding planetary nebulae known. The term “planetary nebula” arose in the 19th century, when the first observations of such objects — through the small telescopes available at the time — looked somewhat like giant planets. However, the true nature of planetary nebulae is quite different.

When a star with a mass similar to or a few times more than that of our Sun approaches the end of its life, its outer layers are thrown off into space. The expanding gas is illuminated by the hot remaining core of the star at the centre, forming the planetary nebula, which often takes on a beautiful, glowing shape. 

When observed with a smaller amateur telescope, this particular planetary nebula shows up as a ring of material, with the star — which will cool to become a white dwarf — shining in the middle of the central hole. This appearance led astronomers to nickname IC 5148 the Spare Tyre Nebula.

The ESO Faint Object Spectrograph and Camera (EFOSC2) on the New Technology Telescope at La Silla gives a somewhat more elegant view of this object. Rather than looking like a spare tyre, the nebula resembles ethereal blossom with layered petals.


8 October 2012

A VISTA Before Sunset

ESO’s Paranal Observatory — located in Chile’s Atacama region — is most well known for the Very Large Telescope (VLT), ESO’s flagship telescope facility. However, over the last few years, the site has also become home to two state-of-the-art survey telescopes. These new members of the Paranal family are designed to image large areas of the sky quickly and deeply.

One of them, the 4.1-metre Visible and Infrared Survey Telescope for Astronomy (VISTA), is located on a neighbouring peak not far from the Paranal summit. It is shown in this beautiful photograph taken from Paranal by ESO Photo Ambassador, Babak Tafreshi. VISTA is the world’s largest survey telescope, and has been operating since December 2009.

At the lower right corner of the image, VISTA’s enclosure appears in front of a seemingly endless mountain range, which stretches to the horizon. As sunset approaches, the mountains cast longer shadows, which slowly cover the brownish tones that colour the magnificent landscape that surrounds Paranal. Soon, the Sun will drop below the horizon, and all the telescopes at Paranal will start another night of observations.

VISTA is a wide-field telescope, designed to map the southern sky in infrared light with high sensitivity, allowing astronomers to detect extremely faint objects. The goal of these surveys is to create large catalogues of celestial objects for statistical studies and to identify new targets that can be studied in more detail by the VLT.

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1 October 2012

Iconic, Conical Licancabur Watches Over Chajnantor

This impressive panoramic image depicts the Chajnantor Plateau — home of the Atacama Large Millimeter/submillimeter Array (ALMA) — with the majestic Licancabur volcano in the background.  Watched over by Licancabur, a icy forest of penitentes (Spanish for “penitents”) cluster in the foreground. The penitentes are a curious natural phenomenon found in high-altitude regions. They are thin spikes of hardened snow or ice, with sharp edges pointing towards the Sun, reaching heights from a few centimetres up to several metres. You can read more about penitentes in a previous Picture of the Week (potw1221).

The Licancabur volcano, with an altitude of 5920 metres, is the most iconic volcano in the area of San Pedro de Atacama, Chile. Its conical shape makes it easily recognisable even from very far away. It is located on the southernmost part of the border between Chile and Bolivia. The volcano contains one of the world’s highest lakes in its summit crater. This lake has attracted the attention of biologists, who are interested on studying how microscopic organisms can survive in it, despite the very harsh environment of intense ultraviolet radiation, the thin atmosphere, and cold temperatures. The survival strategies of microscopic life in Licancabur Lake may even give us insights into the possibility of life on ancient Mars.

This photograph was taken by Babak Tafreshi, one of the ESO Photo Ambassadors, near the ALMA site.

ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), 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.

Links


24 September 2012

A Hard Day's Night Ahead

Sunset is typically a sign that another working day is over. City lights are slowly switched on as people return home eager to enjoy the evening and a good night’s sleep. However, this does not apply to astronomers working at an observatory such as ESO’s Paranal Observatory in Chile. Observing starts as soon as the Sun has disappeared below the horizon. Everything needs to be ready before dusk.

This panoramic photograph captures the ESO Very Large Telescope (VLT) against a beautiful twilight on Cerro Paranal. The enclosures of the VLT stand out in the picture as the telescopes in them are readied for a night of studying the Universe. The VLT is the world’s most powerful advanced optical telescope, consisting of four Unit Telescopes with primary mirrors 8.2 metres in diameter and four movable 1.8-metre Auxiliary Telescopes (ATs), which can be seen in the left corner of the image.

The telescopes can also work together as a single giant telescope, the ESO Very Large Telescope Interferometer (VLTI), which allows astronomers to observe the finest possible detail. This configuration is only used for a limited number of nights per year. Most of the time, the 8.2-metre Unit Telescopes are used individually.

Over the past 13 years, the VLT has had a huge impact on observational astronomy. With the advent of the VLT, the European astronomical community has experienced a new age of discoveries, most notably, the tracking of the stars orbiting the Milky Way’s central black hole and the first image of an extrasolar planet, which are two of the top three of ESO’s Top 10 Astronomical Discoveries.

The VLT’s four Unit Telescopes are named after celestial objects in Mapuche, which is an ancient native language of the indigenous people of Chile and Argentina. From left to right, we have Antu (UT1; the Sun), Kueyen (UT2; the Moon), Melipal (UT3; the Southern Cross) and Yepun (UT4; Venus).

This photograph was taken by ESO Photo Ambassador, Babak Tafreshi.

This image is available as a Mounted Image in the ESOshop.

#L


17 September 2012

ALMA and a Starry Night — a Joy to Behold

A crystal-clear sky on any night is always a joy to behold. But if you are on the Chajnantor Plateau, at 5000 metres altitude in the Chilean Andes and one of the best places in the world for astronomical observations, it could be an experience that you’ll remember for your whole life.

This panoramic view of Chajnantor shows the antennas of the Atacama Large Millimeter/submillimeter Array (ALMA) against a breathtaking starry night sky.

In the foreground, we can see some of ALMA’s antennas, working together. The plateau appears curved, because of the effect of the wide-angle lens used. ALMA is the world’s most powerful telescope for studying the Universe at submillimetre and millimetre wavelengths. Construction work for ALMA will be completed in 2013, and a total of 66 of these high-precision antennas will be operating on the site. At the moment, the telescope is in its initial phase of Early Science Observations. Even though it is not fully constructed, the telescope is already producing outstanding results, outperforming all other submillimetre arrays.

In the sky above the antennas, countless stars shine like distant jewels. Two other familiar celestial objects also stand out. First, the image is crowned by the Moon. Second, outshone by the glow of the Moon, it is possible to distinguish the Milky Way as a hazy stripe across the sky. Dark regions within the band are areas where the light from background stars is blocked by interstellar dust.

This photograph was taken by ESO Photo Ambassador, Babak Tafreshi. Babak is founder and leader of The World At Night, an international project to produce and exhibit a collection of stunning photographs and time-lapse videos of the world’s landmarks with a backdrop of the most beautiful celestial wonders.

ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), 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.

Links


3 September 2012

A Surprising Superbubble

This colourful new view shows the star-forming region LHA 120-N44 [1] in the Large Magellanic Cloud, a small satellite galaxy of the Milky Way. This picture combines the view in visible light from the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile with images in infrared light and X-rays from orbiting satellite observatories.

At the centre of this very rich region of gas, dust and young stars lies the star cluster NGC 1929. Its massive stars produce intense radiation, expel matter at high speeds as stellar winds, and race through their short but brilliant lives to explode as supernovae. The winds and supernova shock waves have carved out a huge cavity, called a superbubble, in the surrounding gas.

Observations with NASA's Chandra X-ray Observatory (shown here in blue) reveal hot regions created by these winds and shocks, while infrared data from NASA's Spitzer Space Telescope (shown in red) outline where the dust and cooler gas are found. The visible-light view from the MPG/ESO 2.2-metre telescope (in yellow) completes the picture and shows the hot young stars themselves as well as the glowing clouds of gas and dust that surround them.

Combining these different views of this dramatic region has allowed astronomers to solve a mystery: why are N44, and similar superbubbles, giving off such strong X-rays? The answer seems to be that there are two extra sources of bright X-ray emission: supernova shock waves striking the walls of the cavities, and hot material evaporating from the cavity walls. This X-ray emission from the edge of the superbubble shows up clearly in the picture.

Links

Notes

[1] The designation of this object indicates that it was included in the Catalogue of H-alpha emission stars and nebulae in the Magellanic Clouds, compiled and published in 1956 by American astronomer–astronaut Karl Henize (1926–1993). The letter “N” indicates that it is a nebula. The object is often called simply N44.


27 August 2012

Night Comes to Paranal

Imagine that you have just watched a beautiful sunset from the top of Cerro Paranal. As the Atacama Desert silently fades into the night, ESO’s Very Large Telescope (VLT) opens its powerful eyes on the Universe. With this spectacular 360-degree panorama, you can imagine the view that you would have if you were standing there, near the southern edge of the VLT’s platform.

In the foreground, the fourth of the VLT’s Auxiliary Telescopes (AT4) is opening. To its left, the Sun has already set over the Pacific Ocean — covered by clouds below the altitude of Paranal, as usual. Across the rest of the platform, the other three Auxiliary Telescopes are seen in front of the large buildings of the four 8.2-metre Unit Telescopes. Finally, the Residencia and other basecamp facilities are also visible a little distance away, near the right-hand edge of the picture.

As the night begins, imagine that you are immersed in a deep silence, barely interrupted by the wind or by the smooth movement of these giant machines. It is hard to believe that intense activity is going on in the VLT Control Building, located on the slope of the mountain just below the level of the platform, in the direction of the setting Sun. There, astronomers and telescope operators are starting the first observations of the night. 

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20 August 2012

Laser Guide Star Sweeps Across a Starry Sky

A powerful laser beam from ESO’s Very Large Telescope (VLT) paints the night sky over the Chilean Atacama Desert in this stunning image taken by Julien Girard. The Earth’s rotation during the 30-minute exposure — and the movement of the laser as it compensated for this — is why the beam appears to fan out. This is also why the stars are stretched into curved trails, revealing subtle differences in their colours.

The laser is used to create a point of light — an artificial star — by making sodium atoms 90 kilometres up in the Earth’s atmosphere glow. Measurements of this so-called guide star are used to correct for the blurring effect of the atmosphere in astronomical observations — a technique known as adaptive optics. While sufficiently bright natural stars are also used for adaptive optics, a laser guide star can be positioned wherever it is needed, meaning that adaptive optics can be used for targets across more of the sky.

The four large enclosures of the VLT’s 8.2-metre Unit Telescopes are visible in the photograph, with the smaller VLT Survey Telescope (VST) in the background. Julien is an ESO astronomer based in Chile, who works at the VLT. On the night this photo was taken, he was supporting observations on the rightmost Unit Telescope, and took the opportunity to set up his camera on a fixed tripod before returning to the control building to make the observations.

The movements of the telescope enclosures during the long exposure also appear as a blur, while faint trails of light, made by people walking across the platform between the telescopes, can also be seen.

Julien 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. In 2012, as part of ESO’s 50th anniversary year, we are also welcoming your historical ESO-related images.

Links


13 August 2012

Orion Watching Over ALMA

Standing watch over the antennas of the Atacama Large Millimeter/submillimeter Array (ALMA), Orion, the Hunter, shines high in the Chilean night sky. With its distinctive hourglass shape and the three bright stars of Orion’s Belt in the centre, the constellation is easily recognisable. Taken from the southern hemisphere, this image shows Orion’s sword above the Belt. The sword is home to one of the most stunning features of the sky — the Orion Nebula — which appears as the middle “star” in the sword, its fuzzy nebulosity visible to the naked eye under good conditions.

The three ALMA antennas visible in the image represent only a small part of the complete ALMA array, which has a total of 66 antennas. ALMA combines the signals from its antennas, separated over distances of up to 16 kilometres, to form a single giant telescope, using a technique called interferometry. While construction is not due to be completed until 2013, early scientific observations began with a partial set of antennas late in 2011.

At 5000 metres altitude on the Chajnantor Plateau in the foothills of the Chilean Andes, in one of the most arid regions in the world, ALMA is guaranteed outstanding observing conditions. A high, dry site such as Chajnantor is needed because water vapour and oxygen in the Earth’s atmosphere strongly absorb the millimetre and submillimetre wavelengths of light at which ALMA is designed to observe.

In this photograph, the antennas were being tested at ALMA’s Operations Support Facility, located at the slightly lower altitude of 2900 metres. Once tested and fully equipped, they were transported up to the Chajnantor plateau to begin their work.

This image was taken by Adrian Russell, who submitted the 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. In 2012, as part of ESO’s 50th anniversary year, we are also welcoming your historical ESO-related images.

ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), 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.

Links


30 July 2012

Red Cocoon Harbours Young Stars

On Earth, cocoons are associated with new life. There are “cocoons” in space too, but, rather than protecting pupae as they transform into moths, they are the birthplaces of new stars.

The red cloud seen in this image, taken with the EFOSC2 instrument on ESO’s New Technology Telescope, is a perfect example of one of these star-forming regions. This is a view of a cloud called RCW 88, which is located about ten thousand light-years away and is about nine light-years across. It is not made of silk, like a moth’s cocoon, but of glowing hydrogen gas that surrounds the recently formed stars. The new stars form from clouds of this hydrogen gas as they collapse under their own gravity. Some of the more developed stars, already shining brightly, can even be seen peering through the cloud.

These hot young stars are very energetic and emit large amounts of ultraviolet radiation, which strips the electrons from the hydrogen atoms in the cloud, leaving the positively charged nuclei — protons. As the electrons are recaptured by the protons, they can emit H-alpha light, which has a characteristic red glow.

Observing the sky through an H-alpha filter is the easiest way for astronomers to find these star-forming regions. A dedicated H-alpha filter was one of the four filters used to produce this image.


23 July 2012

The Paranal basecamp from above

Looking down from a vantage point at the ESO Very Large Telescope on Cerro Paranal in the Chilean Atacama Desert, the observatory’s basecamp stretches out below. The Paranal Residencia, a haven for those working on the mountain, can be seen near the centre with the dome on its roof. To the left of the Residencia, on the other side of the road, is the basecamp’s gymnasium, and to the left of that is the Mirror Maintenance Building (MMB), where the giant VLT mirrors are periodically cleaned and recoated. Behind the MMB is the site’s power station, and further to the left is the mechanical workshop building. Winding up the mountainside in the foreground is the Star Track, a walking path from the Residencia to the summit.

The Sun had set about a quarter of an hour before this photograph was taken, leaving the basecamp bathed in beautiful orange light. This twilight creates gentle shadows which give the hills great depth. Such a sight at Paranal can only be seen during the so-called "golden hours" before sunrise or after sunset, as direct sunlight during the day results in unforgiving lighting contrasts.

This panoramic photograph was created by ESO Photo Ambassador Gerhard Hüdepohl.

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16 July 2012

An ALMA Antenna on the Move

This photograph shows one of the 12-metre-diameter European antennas of the Atacama Large Millimeter/submillimeter Array (ALMA) being moved at the project’s Operations Support Facility. Since this photograph was taken, this antenna, and others like it, have been put into operation as ALMA has begun scientific observations with a partial array (see eso1137). Most recently, the Call for Proposals for ALMA’s next phase of observations closed on Thursday 12 July. Over 1100 proposals were received from astronomers around the world.

ALMA makes its observations on the Chajnantor plateau at an altitude of 5000 metres. Once construction is completed, ALMA will have an array of 66 high-precision 12-metre- and 7-metre-diameter antennas, spread over distances of up to 16 kilometres, working together as a single telescope at wavelengths of 0.32 to 3.6 millimetres. More than half of the 66 antennas are already on Chajnantor (see ann12035). Twenty-five ALMA antennas are being provided by ESO through a contract with the European AEM Consortium, 25 antennas are being provided by North America, and 16 by East Asia.

The antennas, each weighing about 100 tonnes, are assembled and tested at the Operations Support Facility, high in Chile’s Atacama region, at an altitude of 2900 metres. They are moved from there to the Chajnantor plateau, 5000 metres above sea level, with the help of two specially designed ALMA antenna transporters — huge vehicles that drive on 28 tyres, are 10 metres wide, 20 metres long and 6 metres high, weigh 130 tonnes, and have as much power as two Formula 1 engines. One of the transporters, named Otto, is being used in this photograph, which was taken when the first European antenna was handed over to the observatory in April 2011.

ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), 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.


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