Astronomy Cmarchesin

Releases from NASA, NASA Galex, NASA's Goddard Space Flight Center, Hubble, Hinode, Spitzer, Cassini, ESO, ESA, Chandra, HiRISE, Royal Astronomical Society, NRAO, Astronomy Picture of the Day, Harvard-Smithsonian Center For Astrophysics, etc.

Wednesday, April 23, 2014

An X-ray view of the COSMOS field

An X-ray view of the COSMOS field
Copyright: ESA/XMM-Newton/Gunther Hasinger, Nico Cappelluti, and the XMM-COSMOS collaboration.
When we gaze up at the night sky, we are only seeing part of the story. Unfortunately, some of the most powerful and energetic events in the Universe are invisible to our eyes – and to even the best optical telescopes.

Luckily, these events are not lost; they appear vividly in the high-energy sky, making them visible to space-based telescopes like ESA's XMM-Newton, which observes the Universe in the X-ray part of the spectrum.

This image shows a patch of sky from the COSMOS survey, as viewed by XMM-Newton. COSMOS is a project studying how galaxies form and evolve, gathering observations using a variety of ground- and space-based telescopes. This image alone features about two thousand supermassive black holes, and over a hundred clusters of galaxies.

Small point sources dotted across the frame show supermassive black holes that are hungrily devouring matter from their surroundings. All massive galaxies host a black hole at their core, but not all of these are actively accreting, dragging in surrounding matter and releasing high-energy radiation and powerful jets in the process. As they are so energetic, one of the best ways to hunt these extreme bodies is by using X-ray telescopes.

The larger blobs in this image, mainly red and yellow, reveal another class of cosmic behemoths: galaxy clusters. Containing up to several thousand galaxies, galaxy clusters are the largest cosmic structures to be held together by gravity. The galaxies within these clusters are enveloped by hot gas, which releases a diffuse X-ray glow that can be detected by telescopes like XMM-Newton.

The image combines data collected by the EPIC instrument on board XMM-Newton at energies from 0.5 to 2 keV (shown in red), 2 to 4.5 keV (shown in green) and 4.5 to 10 keV (shown in blue). The observations were taken between 2003 and 2005, and the image spans 1.4 degrees on each side, corresponding to almost three times the diameter of the full Moon.

This image was first published in the paper “The XMM-Newton Wide-Field Survey in the COSMOS Field. I. Survey Description” by G. Hasinger et al. in 2007.

Source: ESA

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Tuesday, April 22, 2014

A Dance of Black Holes

Unique pair of supermassive black holes in an ordinary galaxy discovered by XMM-Newton

A pair of supermassive black holes in orbit around one another have been discovered by an international research team including Stefanie Komossa from the Max Planck Institute for Radio Astronomy in Bonn, Germany. This is the first time such a pair could be found in an ordinary galaxy. They were discovered because they ripped apart a star when ESA’s space observatory XMM-Newton happened to be looking in their direction.

The findings are published in the May 10 issue of the “Astrophysical Journal”, and appeared online today at the astrophysics preprint server.

Most massive galaxies in the Universe are thought to harbour at least one supermassive black hole at their centre. Two supermassive black holes are the smoking gun that the galaxy has merged with another. Thus, finding binary supermassive black holes can tell astronomers about how galaxies evolved into their present-day shapes and sizes.

To date, only a few candidates for close binary supermassive black holes have been found. All are in active galaxies where they are constantly ripping gas clouds apart, in the prelude to crushing them out of existence.

In the process of destruction, the gas is heated so much that it shines at many wavelengths, including X-rays. This gives the galaxy an unusually bright centre, and leads to it being called active. The new discovery, reported by Fukun Liu from Peking University in China, and colleagues, is important because it is the first to be found in a galaxy that is not active.

“There might be a whole population of quiescent galaxies that host binary black holes in their centres,” says co-author Stefanie Komossa, Max-Planck-Institut für Radioastronomie, Bonn, Germany. But finding them is a difficult task because in quiescent galaxies, there are no gas clouds feeding the black holes, and so the cores of these galaxies are truly dark.

The only hope that the astronomers have is to be looking in the right direction at the moment one of the black holes goes to work, and rips a star to pieces. Such an occurrence is called a ‘tidal disruption event’. As the star is pulled apart by the gravity of the black hole, it gives out a flare of X-rays.

In an active galaxy, the black hole is continuously fed by gas clouds. In a quiescent galaxy, the black hole is fed by tidal disruption events that occur sporadically and are impossible to predict. So, to increase the chances of catching such an event, researchers use ESA’s X-ray observatory, XMM-Newton, in a novel way.

Usually, the observatory collects data from designated targets, one at a time. Once it completes an observation, it slews to the next. The trick is that during this movement, XMM-Newton keeps the instruments turned on and recording. Effectively this surveys the sky in a random pattern, producing data that can be analysed for unknown or unexpected sources of X-rays.

On 10 June 2010, a tidal disruption event was spotted by XMM-Newton in galaxy SDSS J120136.02+300305.5, approximately 2 billion light years away.  Komossa and her colleagues were scanning the data for such events and scheduled follow-up observations just days later with XMM-Newton and NASA’s Swift satellite.

The galaxy was still spilling X-rays into space. It looked exactly like a tidal disruption event caused by a supermassive black hole but as they tracked the slowly fading emission day after day something strange happened.

The X-rays fell below detectable levels between days 27 and 48 after the discovery. Then they re-appeared and continued to follow a more expected fading rate, as if nothing had happened.

Now, thanks to Fukun Liu, this behaviour can be explained. “This is exactly what you would expect from a pair of supermassive black holes orbiting one another,” says Liu.

Liu had been working on models of black hole binary systems that predicted a sudden plunge to darkness and then the recovery because the gravity of one of the black holes disrupted the flow of gas onto the other, temporarily depriving it of fuel to fire the X-ray flare. He found that two possible configurations were possible to reproduce the observations of J120136.

In the first, the primary black hole contained 10 million solar masses and was orbited by a black hole of about a million solar masses in an elliptical orbit. In the second solution, the primary black hole was about a million solar masses in a circular orbit.

In both cases, the separation between the black holes was relatively small: 0.6 milliparsecs, or about 2 thousandths of a light year. This is about the width of our Solar System.

Being this close, the fate of this newly discovered black hole pair is sealed. They will radiate their orbital energy away, gradually spiralling together, until in about two million years time they will merge into a single black hole.

Now that astronomers have found this first candidate for a binary black hole in a quiescent galaxy, the search is inevitably on for more. XMM-Newton will continue its slew survey. This detection will also spur interest in a network of telescopes that search the whole sky for tidal disruption events.

“Once we have detected thousands of tidal disruption events, we can begin to extract reliable statistics about the rate at which galaxies merge,” says Stefanie Komossa.

When binary black holes merge, they are predicted to release a massive burst of energy into the Universe but not mostly in X-rays. “The final merger is expected to be the strongest source of gravitational waves in the Universe,” states Fukun Liu.

 “The innovative use of XMM-Newton’s slew observations made the detection of this binary supermassive black hole system possible,” concludes Norbert Schartel, ESA's XMM-Newton Project Scientist. “This demonstrates the important role that long-lasting space observatories have in detecting such rare events that can potentially open new areas in astronomy.” 

Background Information:

Original Paper:

F.K. Liu, Shuo Li, and S. Komossa, published in: 2014, Astrophysical Journal, Volume 786, Article 103 (May 10). DOI:10.1088/0004-637X/786/2/103. arXiv:1404.4933 [astro-ph.HE]


Dr. Stefanie Komossa
Phone:+49 228 525-431
Max-Planck-Institut für Radioastronomie, Bonn

Dr. Norbert Schartel
ESA XMM-Newton Projektwissenschaftler
Phone:+34 91 8131-184
Europäische Raumfahrtagentur (ESA)

Dr. Norbert Junkes Presse- und Öffentlichkeitsarbeit
Phone:+49 228 525-399
Max-Planck-Institut für Radioastronomie, Bonn

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A New Map of the Galaxy in the Light of Atomic Hydrogen

A new image of the Lagoon Nebula as seen with the VPHAS+ survey in the light of atomic hydrogen. The survey has just begun to return science results; there are roughly 300 million objects in its catalog. (Video link)

Atomic hydrogen is the lightest and by far most abundant element in the universe. When it is exposed to ultraviolet light, its single electron can be stripped from the atom, a situation that arises near stars that are hot. When a free electron then reunites with a proton to form a neutral atom it emits light including the visible H-alpha emission line. A region of H-alpha emission - a nebula - thus signals the presence of ionized gas near a hot star.

Typically stars are hot either because they are young and massive or because their nuclear burning has progressed to a hotter phase; they include O-stars, Be stars, supergiants, luminous blue variable stars, Wolf-Rayet stars, as well as very young stars of all masses and compact interacting binary stars. Surveys that take images in H-alpha emission are thus excellent detectors of hot stars and associated phenomena, not least because nebulae are comparatively larger in size and easier to spot than are the point-like stars that heat them.

In the southern hemisphere, the last time anyone published a systematic survey of H-alpha light was in 1971, and that study has been a standard astronomical resource ever since. But no longer. CfA astronomer Jeremy Drake has joined a large team of colleagues to make a new H-alpha study of the southern galactic plane, called VPHAS+ (the VST Photometric H-alpha Survey), with the plus indicating that four optical wavelengths are also surveyed in addition to the H-alpha wavelength.

The VPHAS+ catalog, which is soon to be completed, will have about 300 million stars, and will include stars and nebulae that are as much as 1500 times fainter than the ones in the older catalog, as well as much improved images of all objects. Because dust obscures optical light, the new survey will also be able to spot objects that previously were too obscured for detection. The first set of papers using this new catalog have started to appear, and as the data pipeline and calibration progresses the community expects this catalog to become a standard reference and a tool for exploration of the ultraviolet Milky Way.

"The VST Photometric Hα Survey of the Southern Galactic Plane and Bulge (VPHAS+)," J. E. Drew et al., MNRAS 440, 2036, 2014.

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Monday, April 21, 2014

Sun Emits a Mid-level Solar Flare

The sun emitted a mid-level solar flare, peaking at 9:03 a.m. EDT on April 18, 2014, and NASA's Solar Dynamics Observatory captured images of the event. Solar flares are powerful bursts of radiation. Harmful radiation from a flare cannot pass through Earth's atmosphere to physically affect humans on the ground, however -- when intense enough -- they can disturb the atmosphere in the layer where GPS and communications signals travel.

A mid-level flare burst from the sun on April 18, 2014, as seen as a bright spot in the center of this image. The image was captured by NASA's Solar Dynamics Observatory in 304 angstrom.Image Credit: NASA/SDO. View a full disk image in 131 angstrom

To see how this event may impact Earth, please visit NOAA's Space Weather Prediction Center at, the U.S. government's official source for space weather forecasts, alerts, watches and warnings.

This flare is classified as an M7-class flare. M-class flares are one step below the most intense flares, which are designated as X-class.

Updates will be provided as needed.

Related Links
Karen C. Fox
NASA's Goddard Space Flight Center, Greenbelt, Md.

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Friday, April 18, 2014

Galaxies spiralling around Leo

Credit: ESA/Hubble & NASA
Acknowledgement: Nick Rose
Shown here is a spiral galaxy known as NGC 3455, which lies some 65 million light-years away from us in the constellation of Leo (The Lion).

Galaxies are classified into different types according to their structure and appearance. This classification system is known as the Hubble Sequence, named after its creator Edwin Hubble.

In this sequence, NGC 3455 is known as a type SB galaxy — a barred spiral. Barred spiral galaxies account for approximately two thirds of all spirals. Galaxies of this type appear to have a bar of stars slicing through the bulge of stars at their centre. The SB classification is further sub-divided by the appearance of a galaxy's pinwheeling spiral arms; SBa types have more tightly wound arms, whereas SBc types have looser ones. SBb types, such as NGC 3455, lie in between.

NGC 3455 is part of a pair of galaxies — its partner, NGC 3454, lies out of frame. This cosmic duo belong to a group known as the NGC 3370 group, which is in turn one of the Leo II groups, a large collection of galaxies scattered some 30 million light-years to the right of the Virgo cluster.

This new image is from Hubble's Advanced Camera for Surveys (ACS). A version of this image was entered into the Hubble's Hidden Treasures image processing competition by contestant Nick Rose.

Source: ESA/Hubble  - Space Telescope

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NASA's Kepler Discovers First Earth-Size Planet In The 'Habitable Zone' of Another Star

The artist's concept depicts Kepler-186f , the first validated Earth-size planet to orbit a distant star in the habitable zone. Image Credit: NASA Ames/SETI Institute/JPL-Caltech. Kepler-186f, the first Earth-size Planet in the Habitable Zone
The diagram compares the planets of our inner solar system to Kepler-186, a five-planet star system about 500 light-years from Earth in the constellation Cygnus. The five planets of Kepler-186 orbit an M dwarf, a star that is is half the size and mass of the sun. Image Credit: NASA Ames/SETI Institute/JPL-Caltech. Kepler-186 and the Solar System
Using NASA's Kepler Space Telescope, astronomers have discovered the first Earth-size planet orbiting a star in the "habitable zone" -- the range of distance from a star where liquid water might pool on the surface of an orbiting planet. The discovery of Kepler-186f confirms that planets the size of Earth exist in the habitable zone of stars other than our sun.

While planets have previously been found in the habitable zone, they are all at least 40 percent larger in size than Earth and understanding their makeup is challenging. Kepler-186f is more reminiscent of Earth.

"The discovery of Kepler-186f is a significant step toward finding worlds like our planet Earth," said Paul Hertz, NASA's Astrophysics Division director at the agency's headquarters in Washington. "Future NASA missions, like the Transiting Exoplanet Survey Satellite and the James Webb Space Telescope, will discover the nearest rocky exoplanets and determine their composition and atmospheric conditions, continuing humankind's quest to find truly Earth-like worlds."

Although the size of Kepler-186f is known, its mass and composition are not. Previous research, however, suggests that a planet the size of Kepler-186f is likely to be rocky.

"We know of just one planet where life exists -- Earth. When we search for life outside our solar system we focus on finding planets with characteristics that mimic that of Earth," said Elisa Quintana, research scientist at the SETI Institute at NASA's Ames Research Center in Moffett Field, Calif., and lead author of the paper published today in the journal Science. "Finding a habitable zone planet comparable to Earth in size is a major step forward."

Kepler-186f resides in the Kepler-186 system, about 500 light-years from Earth in the constellation Cygnus. The system is also home to four companion planets, which orbit a star half the size and mass of our sun. The star is classified as an M dwarf, or red dwarf, a class of stars that makes up 70 percent of the stars in the Milky Way galaxy.

"M dwarfs are the most numerous stars," said Quintana. "The first signs of other life in the galaxy may well come from planets orbiting an M dwarf."

Kepler-186f orbits its star once every 130-days and receives one-third the energy from its star that Earth gets from the sun, placing it nearer the outer edge of the habitable zone. On the surface of Kepler-186f, the brightness of its star at high noon is only as bright as our sun appears to us about an hour before sunset.
"Being in the habitable zone does not mean we know this planet is habitable. The temperature on the planet is strongly dependent on what kind of atmosphere the planet has," said Thomas Barclay, research scientist at the Bay Area Environmental Research Institute at Ames, and co-author of the paper. "Kepler-186f can be thought of as an Earth-cousin rather than an Earth-twin. It has many properties that resemble Earth."

The four companion planets, Kepler-186b, Kepler-186c, Kepler-186d, and Kepler-186e, whiz around their sun every four, seven, 13, and 22 days, respectively, making them too hot for life as we know it. These four inner planets all measure less than 1.5 times the size of Earth.

The next steps in the search for distant life include looking for true Earth-twins -- Earth-size planets orbiting within the habitable zone of a sun-like star -- and measuring the their chemical compositions. The Kepler Space Telescope, which simultaneously and continuously measured the brightness of more than 150,000 stars, is NASA's first mission capable of detecting Earth-size planets around stars like our sun.

Ames is responsible for Kepler's ground system development, mission operations, and science data analysis. NASA's Jet Propulsion Laboratory in Pasadena, Calif., managed Kepler mission development. Ball Aerospace & Technologies Corp. in Boulder, Colo., developed the Kepler flight system and supports mission operations with the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder. The Space Telescope Science Institute in Baltimore archives, hosts and distributes Kepler science data. Kepler is NASA's 10th Discovery Mission and was funded by the agency's Science Mission Directorate.

The SETI Institute is a private, nonprofit organization dedicated to scientific research, education and public outreach.  The mission of the SETI Institute is to explore, understand and explain the origin, nature and prevalence of life in the universe.

For more information about the Kepler mission, visit:

Media contacts:

Michele Johnson
Ames Research Center, Moffett Field, Calif.

J.D. Harrington
Headquarters, Washington

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Thursday, April 17, 2014

A cross-section of the Universe

Hubble’s cross-section of the cosmos
Annotated image of the field around CLASS B1608+656
Digitized Sky Survey Image around CLASS B1608+656 
(ground-based image)



Zoom in on CLASS B1608+656
Zoom in on CLASS B1608+656

Pan across CLASS B1608+656
Pan across CLASS B1608+656

An image of a galaxy cluster taken by the NASA/ESA Hubble Space Telescope gives a remarkable cross-section of the Universe, showing objects at different distances and stages in cosmic history. They range from cosmic near neighbours to objects seen in the early years of the Universe. The 14-hour exposure shows objects around a billion times fainter than can be seen with the naked eye.

This new Hubble image showcases a remarkable variety of objects at different distances from us, extending back over halfway to the edge of the observable Universe. The galaxies in this image mostly lie about five billion light-years from Earth but the field also contains other objects, both significantly closer and far more distant.

Studies of this region of the sky have shown that many of the objects that appear to lie close together may actually be billions of light-years apart. This is because several groups of galaxies lie along our line of sight, creating something of an optical illusion. Hubble’s cross-section of the Universe is completed by distorted images of galaxies in the very distant background.

These objects are sometimes distorted due to a process called gravitational lensing, an extremely valuable technique in astronomy for studying very distant objects [1]. This lensing is caused by the bending of the space-time continuum by massive galaxies lying close to our line of sight to distant objects.

One of the lens systems visible here is called CLASS B1608+656, which appears as a small loop in the centre of the image. It features two foreground galaxies distorting and amplifying the light of a distant quasar the known as QSO-160913+653228. The light from this bright disc of matter, which is currently falling into a black hole, has taken nine billion years to reach us — two thirds of the age of the Universe.

As well as CLASS B1608+656, astronomers have identified two other gravitational lenses within this image. Two galaxies, dubbed Fred and Ginger by the researchers who studied them, contain enough mass to visibly distort the light from objects behind them. Fred, also known more prosaically as [FMK2006] ACS J160919+6532, lies near the lens galaxies in CLASS B1608+656, while Ginger ([FMK2006] ACS J160910+6532) is markedly closer to us. Despite their different distances from us, both can be seen near to CLASS B1608+656 in the central region of this Hubble image.

To capture distant and dim objects like these, Hubble required a long exposure. The image is made up of visible and infrared observations with a total exposure time of 14 hours.


[1] Gravitational lensing can amplify the light coming from distant objects, enabling telescopes like Hubble to see objects that would otherwise be too faint and far away. This effect will be exploited during the Frontier Fields observing campaign in the near future, which aims to combine the power of Hubble with the natural amplification caused by strong gravitational lensing of distant galaxy clusters, to study the past Universe.

More information

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

The image was spotted by contestant Adam Kill in the 2012 Hubble's Hidden Treasures competition. Hidden Treasures invited members of the public to search Hubble's science for the best overlooked images that have never been seen by a general audience. This image of CLASS B1608+656 has been well-studied by scientists over the years, but this is the first time it has been published in full online.



Georgia Bladon
Garching, Germany
Tel: +49-89-3200-6855

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Wednesday, April 16, 2014

A Study in Scarlet

The star formation region Gum 41
The star formation region Gum 41 in the constellation of Centaurus



Zooming in on the star formation region Gum 41
Zooming in on the star formation region Gum 41

Panning across the star formation region Gum 41
Panning across the star formation region Gum 41

This new image from ESO’s La Silla Observatory in Chile reveals a cloud of hydrogen called Gum 41. In the middle of this little-known nebula, brilliant hot young stars are giving off energetic radiation that causes the surrounding hydrogen to glow with a characteristic red hue.

This area of the southern sky, in the constellation of Centaurus (The Centaur), is home to many bright nebulae, each associated with hot newborn stars that formed out of the clouds of hydrogen gas. The intense radiation from the stellar newborns excites the remaining hydrogen around them, making the gas glow in the distinctive shade of red typical of star-forming regions. Another famous example of this phenomenon is the Lagoon Nebula (eso0936), a vast cloud that glows in similar bright shades of scarlet.

The nebula in this picture is located some 7300 light-years from Earth. Australian astronomer Colin Gum discovered it on photographs taken at the Mount Stromlo Observatory near Canberra, and included it in his catalogue of 84 emission nebulae, published in 1955. Gum 41 is actually one small part of a bigger structure called the Lambda Centauri Nebula, also known by the more exotic name of the Running Chicken Nebula (another part of which was the topic of eso1135). Gum died at a tragically early age in a skiing accident in Switzerland in 1960.

In this picture of Gum 41, the clouds appear to be quite thick and bright, but this is actually misleading. If a hypothetical human space traveller could pass through this nebula, it is likely that they would not notice it as — even at close quarters — it would be too faint for the human eye to see. This helps to explain why this large object had to wait until the mid-twentieth century to be discovered — its light is spread very thinly and the red glow cannot be well seen visually.

This new portrait of Gum 41 — likely one of the best so far of this elusive object — has been created using data from the Wide Field Imager (WFI) on the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile. It is a combination of images taken through blue, green, and red filters, along with an image using a special filter designed to pick out the red glow from hydrogen.

More information

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”.



Richard Hook
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591

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Aussie Scientist Finds Rare Supernova at Keck Observatory

Can you spot the supernova?
Credit:  Forbes/WMKO

It was a dark and stormy night in the city of Angels. Well, actually it wasn't. But more on that later...

It was a clear night on the summit of Mauna Kea at Keck Observatory on the 20th March. My colleagues and I were using the Echellette Spectrograph and Imager (ESI) instrument, which looks at faint objects in the visible wavelengths, to study star clusters and small galaxies.

I was actually in our special ‘remote ops’ room at Swinburne University, with my postdoc, Joachim Janz. This is a room decked out with a computer, a backup computer, a video-link to Keck Observatory and a dedicated Internet connection. As we are 21 hours ahead of Hawaii, it was a Friday afternoon when we started observing that Thursday night. My colleagues Sam Penny and Mark Norris were in the Keck control room, and Aaron Romanowsky was in his remote ops room at UC Santa Cruz.

Shortly into our night's observing, we noticed a bright source in the guide camera image that wasn't on our finding chart of that region. Still we managed to find our target and took a spectrum of it. But we decided to go back and see if that `new' bright source was still there. Sure enough it was and it hadn't moved. It was probably a supernova (or an asteroid coming straight at us!), so I decided to get a 5min spectrum with ESI. And indeed we had found a supernova—a type Ia to be exact. Type Ia supernovae are fairly rare in the nearby Universe and represent the explosion of at least one white dwarf star in a binary system. It is this same type of supernova that led to the discovery of Dark Energy in the Universe using the Keck Observatory, and three Nobel prizes. 

Our supernova is located in the outskirts of a galaxy some 100 million light years from us—so it exploded 100 million years ago but the light only reached us that night. 

I later found out that an automated telescope on the Palomar Mountain overlooking Los Angeles detected the supernova shortly before us. They also managed to get a spectrum but that was taken after our Keck II/ESI spectrum. The exciting thing is that both the Palomar Observatory and ourselves managed to observe the supernova in the 1-2 weeks before it reaches its maximum brightness (and then fades steadily after that).
The supernova has been given the designation SN2014ai.

All in all, not bad for a late night at the office...

By Prof. Duncan Forbes

Duncan Forbes is a professor of astronomy at Swinburne University in Melbourne, Australia, and a 2014 Evenings with Astronomers presenter at the signature Friends of Keck lecture series. Swinburne astronomers are awarded time for their research on Keck Observatory through an agreement with the California Institute of Technology. 

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Tuesday, April 15, 2014

NASA Cassini Images May Reveal Birth of a Saturn Moon

The disturbance visible at the outer edge of Saturn's A ring in this image from NASA's Cassini spacecraft could be caused by an object replaying the birth process of icy moons.  Full image and caption

NASA's Cassini spacecraft has documented the formation of a small icy object within the rings of Saturn that may be a new moon, and may also provide clues to the formation of the planet's known moons.

Images taken with Cassini's narrow angle camera on April 15, 2013, show disturbances at the very edge of Saturn's A ring -- the outermost of the planet's large, bright rings. One of these disturbances is an arc about 20 percent brighter than its surroundings, 750 miles (1,200 kilometers) long and 6 miles (10 kilometers) wide. Scientists also found unusual protuberances in the usually smooth profile at the ring's edge. Scientists believe the arc and protuberances are caused by the gravitational effects of a nearby object. Details of the observations were published online today (April 14, 2014) by the journal Icarus.

The object is not expected to grow any larger, and may even be falling apart. But the process of its formation and outward movement aids in our understanding of how Saturn's icy moons, including the cloud-wrapped Titan and ocean-holding Enceladus, may have formed in more massive rings long ago. It also provides insight into how Earth and other planets in our solar system may have formed and migrated away from our star, the sun.

"We have not seen anything like this before," said Carl Murray of Queen Mary University of London, the report's lead author. "We may be looking at the act of birth, where this object is just leaving the rings and heading off to be a moon in its own right."

The object, informally named Peggy, is too small to be seen in images so far. Scientists estimate it is probably no more than about a half mile (about a kilometer) in diameter. Saturn's icy moons range in size depending on their proximity to the planet -- the farther from the planet, the larger. And many of Saturn's moons are composed primarily of ice, as are the particles that form Saturn's rings. Based on these facts, and other indicators, researchers recently proposed that the icy moons formed from ring particles and then moved outward, away from the planet, merging with other moons on the way.

"Witnessing the possible birth of a tiny moon is an exciting, unexpected event," said Cassini Project Scientist Linda Spilker, of NASA's Jet Propulsion Laboratory in Pasadena, Calif. According to Spilker, Cassini's orbit will move closer to the outer edge of the A ring in late 2016 and provide an opportunity to study Peggy in more detail and perhaps even image it.

It is possible the process of moon formation in Saturn's rings has ended with Peggy, as Saturn's rings now are, in all likelihood, too depleted to make more moons. Because they may not observe this process again, Murray and his colleagues are wringing from the observations all they can learn.

"The theory holds that Saturn long ago had a much more massive ring system capable of giving birth to larger moons," Murray said. "As the moons formed near the edge, they depleted the rings and evolved, so the ones that formed earliest are the largest and the farthest out." 

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology, manages the mission for NASA's Science Mission Directorate in Washington. 

To view an image of the Saturn ring disturbance attributed to the new moon, visit:

For more information about Cassini, visit these sites:

Jane Platt
Jet Propulsion Laboratory, Pasadena, Calif.

Dwayne Brown
Headquarters, Washington


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Monday, April 14, 2014

Faraway Moon or Faint Star? Possible Exomoon Found

Researchers have detected the first "exomoon" candidate -- a moon orbiting a planet that lies outside our solar system. Image credit: NASA/JPL-Caltech.  Full image and caption

Titan, Europa, Io and Phobos are just a few members of our solar system's pantheon of moons. Are there are other moons out there, orbiting planets beyond our sun? 

NASA-funded researchers have spotted the first signs of an "exomoon," and though they say it's impossible to confirm its presence, the finding is a tantalizing first step toward locating others. The discovery was made by watching a chance encounter of objects in our galaxy, which can be witnessed only once.

"We won't have a chance to observe the exomoon candidate again," said David Bennett of the University of Notre Dame, Ind., lead author of a new paper on the findings appearing in the Astrophysical Journal. "But we can expect more unexpected finds like this." 

The international study is led by the joint Japan-New Zealand-American Microlensing Observations in Astrophysics (MOA) and the Probing Lensing Anomalies NETwork (PLANET) programs, using telescopes in New Zealand and Tasmania. Their technique, called gravitational microlensing, takes advantage of chance alignments between stars. When a foreground star passes between us and a more distant star, the closer star can act like a magnifying glass to focus and brighten the light of the more distant one. These brightening events usually last about a month.

If the foreground star -- or what astronomers refer to as the lens -- has a planet circling around it, the planet will act as a second lens to brighten or dim the light even more. By carefully scrutinizing these brightening events, astronomers can figure out the mass of the foreground star relative to its planet. 

In some cases, however, the foreground object could be a free-floating planet, not a star. Researchers might then be able to measure the mass of the planet relative to its orbiting companion: a moon. While astronomers are actively looking for exomoons -- for example, using data from NASA's Kepler mission - so far, they have not found any.

In the new study, the nature of the foreground, lensing object is not clear. The ratio of the larger body to its smaller companion is 2,000 to 1. That means the pair could be either a small, faint star circled by a planet about 18 times the mass of Earth -- or a planet more massive than Jupiter coupled with a moon weighing less than Earth.

The problem is that astronomers have no way of telling which of these two scenarios is correct. 

"One possibility is for the lensing system to be a planet and its moon, which if true, would be a spectacular discovery of a totally new type of system," said Wes Traub, the chief scientist for NASA's Exoplanet Exploration Program office at NASA's Jet Propulsion Laboratory, Pasadena, Calif., who was not involved in the study. "The researchers' models point to the moon solution, but if you simply look at what scenario is more likely in nature, the star solution wins." 

The answer to the mystery lies in learning the distance to the circling duo. A lower-mass pair closer to Earth will produce the same kind of brightening event as a more massive pair located farther away. But once a brightening event is over, it's very difficult to take additional measurements of the lensing system and determine the distance. The true identity of the exomoon candidate and its companion, a system dubbed MOA-2011-BLG-262, will remain unknown.

In the future, however, it may be possible to obtain these distance measurements during lensing events. For example, NASA's Spitzer and Kepler space telescopes, both of which revolve around the sun in Earth-trailing orbits, are far enough away from Earth to be great tools for the parallax-distance technique. 

The basic principle of parallax can be explained by holding your finger out, closing one eye after the other, and watching your finger jump back and forth. A distant star, when viewed from two telescopes spaced really far apart, will also appear to move. When combined with a lensing event, the parallax effect alters how a telescope will view the resulting magnification of starlight. Though the technique works best using one telescope on Earth and one in space, such as Spitzer or Kepler, two ground-based telescopes on different sides of our planet can also be used.

Meanwhile, surveys like MOA and the Polish Optical Gravitational Experiment Lensing Experiment, or OGLE, are turning up more and more planets. These microlensing surveys have discovered dozens of exoplanets so far, in orbit around stars and free-floating. A previous NASA-funded study, also led by the MOA team, was the first to find strong evidence for planets the size of Jupiter roaming alone in space, presumably after they were kicked out of forming planetary systems. (See

The new exomoon candidate, if real, would orbit one such free-floating planet. The planet may have been ejected from the dusty confines of a young planetary system, while keeping its companion moon in tow.

The ground-based telescopes used in the study are the Mount John University Observatory in New Zealand and the Mount Canopus Observatory in Tasmania. 

Additional observations were obtained with the W.M. Keck Observatory in Mauna Kea, Hawaii; European Southern Observatory's VISTA telescope in Chile; the Optical Gravitational Lens Experiment (OGLE) using the Las Campanas Observatory in Chile; the Microlensing Follow-Up Network (MicroFUN) using the Cerro Tololo Interamerican Observatory in Chile; and the Robonet Collaboration using the Faulkes Telescope South in Siding Spring, Australia.

Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.

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Friday, April 11, 2014

Hubble Stretches Stellar Tape Measure 10 Times Farther into Space

This illustration shows how the precision stellar distance measurements from NASA's Hubble Space Telescope have been extended 10 times farther into our Milky Way galaxy than possible previously. This greatly extends the volume of space accessible to refining the cosmic yardstick needed for measuring the size of the universe. This most solid type of measurement is based on trigonometric parallax, which is commonly used by surveyors. Because the stars are vastly farther away than a surveyor's sightline, Hubble must measure extremely small angles on the sky.  

Illustration Credit: NASA, ESA, and A. Feild (STScI). Science Credit: NASA, ESA, A. Riess (JHU/STScI), S. Casertano (STScI/JHU), J. Anderson and J. MacKenty (STScI), and A. Filippenko (University of California, Berkeley)

Even though NASA's Hubble Space Telescope is 24 years old, astronomers are still coming up with imaginative, novel, and groundbreaking new uses for it. The latest is an innovative technique that improves Hubble's observing accuracy to the point where rock-solid distance measurements can be made to Milky Way stars 10 times farther away than ever accomplished before.

To do this, Hubble observations and subsequent analysis were fine-tuned to make angular measurements (needed for estimating distances) that are so fine that if your eyes had a similar capability you could read a car's license plate located as far away as the Moon!

This new capability allows astronomers to use even more distant stars as yardsticks to refine estimates. In addition, it is expected to yield new insight into the nature of dark energy, a mysterious component of space that is pushing the universe apart at an ever-faster rate.

As proof of concept for this new long-range precision, Hubble was used to measure the distance to a bright star of a special class (called Cepheid variables) that is located approximately 7,500 light-years away in the northern constellation Auriga. The technique worked so well that additional Hubble distance measurements to other far-flung Cepheids are being measured.

Such measurements will be used to provide firmer footing for the so-called cosmic "distance ladder." This ladder's "bottom rung" is built on measurements to Cepheid variable stars that, because of their known intrinsic brightnesses, have been used for more that a century to gauge the size of the observable universe. They are the first step in calibrating far-more-distant intergalactic milepost markers, such as Type Ia supernovae.

The most reliable method for making astronomical distance measurements is to use straightforward geometry where the 186-million-mile diameter of Earth's orbit is used to construct a baseline of a triangle, much as a land surveyor would use. If a target star is close enough, it will appear to zigzag on the sky during the year as a reflection of Earth's orbit about the Sun. This technique is called parallax.

Astronomical parallax works reliably for stars within a few hundred light-years of Earth. For example, the position of the nearest star system to our Sun, Alpha Centauri, varies due to parallax by only one arc second on the sky during the year, which is equal to the apparent width of a dime seen from two miles away.

But the farther away the star, the smaller the angle of its apparent back-and-forth motion, until the offset is so small it can barely be measured. Astronomers have pushed to make ever smaller angular measurements to extend the parallax yardstick ever deeper into our galaxy.

Noble Laureate Adam Riess of the Space Telescope Science Institute (STScI) and the Johns Hopkins University in Baltimore, Md., in collaboration with Stefano Casertano of STScI, developed an ingenious technique to use Hubble to make measurements as fine as five-billionths of a degree on the sky. (A degree is twice the angular width of the full moon.)

Riess imagined that if Hubble could take numerous exposures of a target star quickly, he could combine the data to measure extremely small angles on the sky. But rather than taking multiple exposures, Riess had the stars trail across Hubble's imaging detector to leave linear streaks. Riess says that he got the idea for how to do the observation while swimming laps in lanes that are long, linear swaths, like the stellar images streaked across the detector. Infinitesimal offsets in the streaks that could be caused by parallax were measured through new image analysis techniques developed by Casertano and Riess.

To make a distance measurement, exposures of the target Cepheid star were taken every six months, when Earth is on opposite sides of the Sun. A very subtle shift in the Cepheid's position was measured to an accuracy of 1/1000 the width of a single picture element (pixel) in Hubble's Wide Field Camera 3 (which has 16.8 megapixels total). A third exposure was taken 12 months after the first observation to allow for the team to subtract the effects of the subtle space motion of stars, with additional exposures used to remove other sources of error.

Riess shares the 2011 Nobel Prize in Physics with another team for his leadership in the 1998 discovery that the expansion rate of the universe is accelerating, a phenomenon widely attributed to a mysterious, unexplained "dark energy" filling the universe. His goal is to refine estimates for the universe's expansion rate to the point where dark energy can be better characterized.


Ray Villard
Space Telescope Science Institute, Baltimore, Md.

Adam Riess
Space Telescope Science Institute/Johns Hopkins University, Baltimore, Md.

 Source: HubbleSite

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Thursday, April 10, 2014

G352.7-0.1: Supernova Cleans Up its Surroundings

Supernova Remnant -  G352.7-0.1 
Credit X-ray: NASA/CXC/Morehead State Univ/T.Pannuti et al.; 
Optical: DSS; Infrared: NASA/JPL-Caltech; 
Radio: NRAO/VLA/Argentinian Institute of Radioastronomy/G.Dubner


Supernovas are the spectacular ends to the lives of many massive stars. These explosions, which occur on average twice a century in the Milky Way, can produce enormous amounts of energy and be as bright as an entire galaxy. These events are also important because the remains of the shattered star are hurled into space. As this debris field - called a supernova remnant - expands, it carries the material it encounters along with it.
Astronomers have identified a supernova remnant that has several unusual properties. First, they found that this supernova remnant - known as G352.7-0.1 (or, G352 for short) - has swept up a remarkable amount of material, equivalent to about 45 times the mass of the Sun.

Another atypical trait of G352 is that it has a very different shape in radio data compared to that in X-rays. Most of the radio emission is shaped like an ellipse, contrasting with the X-ray emission that fills in the center of the radio ellipse. This is seen in a new composite image of G352 that contains X-rays from NASA's

Chandra X-ray Observatory in blue and radio data from the National Science Foundation's Karl G. Jansky Very Large Array in pink. These data have also been combined with infrared data from the Spitzer Space Telescope in orange, and optical data from the Digitized Sky Survey in white. (The infrared emission to the upper left and lower right are not directly related to the supernova remnant.)

A recent study suggests that, surprisingly, the X-ray emission in G352 is dominated by the hotter (about 30 million degrees Celsius) debris from the explosion, rather than cooler (about 2 million degrees) emission from surrounding material that has been swept up by the expanding shock wave. This is curious because astronomers estimate that G352 exploded about 2,200 years ago, and supernova remnants of this age usually produce X-rays that are dominated by swept-up material. Scientists are still trying to come up with an explanation for this behavior.

Although it does not produce a lot of X-ray emission, the amount of material - the aforementioned 45 times the Sun's mass - swept up by G352 is remarkably high for a supernova remnant located in our Galaxy. This may indicate that a special type of evolution has occurred, in which the massive star that exploded to create G352 interacted with an extraordinary amount of dense surrounding material.

Astronomers also conducted a search for a neutron star that may have been produced by the supernova explosion. They did not find any hints of a neutron star in G352, another astronomical puzzle involved with this system. One possibility is simply that the neutron star is too faint to be detected or that the supernova created a black hole instead.

G352 is found about 24,000 light years from Earth in the Milky Way galaxy. A paper describing these enigmatic results was published in the February 20th, 2014 issue of The Astrophysical Journal, and is available online. The first author of this paper is Thomas Pannuti from Morehead State University in Morehead, Kentucky, with co-authors Oleg Kargaltsev (George Washington University), Jared Napier (Morehead State), and Derek Brehm (George Washington).

Fast Facts for G352.7-0.1: 

Category: Supernovas & Supernova Remnants
Coordinates (J2000): RA 17h 27m 41.00s | Dec -35° 06' 45.00" 
Constellation: Scorpius
Observation Date: 06 Oct 2004 
Observation Time: 12 hours 23 min 
Obs. ID: 4652 
Instrument: ACIS
References: Pannuti, T. et al. 2014, ApJ 782, 102; arXiv:1401.6603
Color Code: X-ray (Blue); Optical (Grayscale); Infrared (Orange); Radio (Pink) 
Distance Estimate: 24,000 light years

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Cosmology and the Spatial Distribution of Galaxies

Sound waves that propagate in the early universe, like spreading ripples in a pond, imprint a characteristic scale on cosmic microwave background fluctuations. These fluctuations have evolved today into the clustering of galaxies. The concept is illustrated here. SDSS III, BOSS 

Perhaps the most astonishing and revolutionary discovery in cosmology was that galaxies are moving away from us. Hubble's 1929 paper provides the underpinning of the big bang picture of creation in which the universe is expanding, and has been for 13.8 billion years. Astronomers since then have been steadily working to refine this general picture, and in 1998, two teams (one led by CfA scientists) further astonished the world with their results showing that the universe would expand forever -- and not only that: it is accelerating outward. They used supernovae to probe the distant cosmos. These discoveries have led to more sophisticated questions, with a primary task today being to understand in detail the expansion history of the universe, that is, how the rate of expansion of the universe evolved from the time of the big bang to the way it is today. The answers to this question directly address the properties of the acceleration mechanism, the nature of dark matter, the evolution of galaxies in early times, and more.

Precision measurements of the cosmic distance scale are crucial for probing this behavior, and one particularly powerful method uses what are called baryon acoustic oscillations (BAO). Baryons refer to ordinary matter, and acoustic oscillations are sound waves. Sound waves caused by density fluctuations were bouncing through the cosmos during its first 400,000 years. Then, once ionized atoms became neutral, radiation no longer interacted strongly with matter and the cosmic microwave background was released. The intensity maps of the background radiation contain a record of these sound waves – the BAO. Astronomers calculate that at the time the cosmic background was produced, sound waves (traveling at the speed of sound) could have spread across a distance of about 500 million light-years, leaving in their wake a coherent record in the matter distribution that eventually condensed into galaxies and clusters of galaxies. Because the scale of this acoustic distortion is so large, many times the size of galaxy clusters, the BAO signature was only modestly altered subsequently as the universe evolved; simulations and theory suggest deviations are below 1%. The robustness of the scale of this distinctive clustering signature allows it to be used as a standard ruler to measure the cosmic distance scale, and indeed the imprint of the BAOs has been detected in a variety of observations of the structure of the nearby universe.

CfA astronomers Daniel Eisenstein and Cameron McBride were among a large team of scientists probing BAOs by using the clustering of galaxies as seen at a time when the universe was about 8.2 billion years old. They examined 264,283 galaxies of this general epoch observed by the Sloan Digital Sky Survey, and measured from their spatial distribution the signature of the acoustic waves left behind to a precision of better than 10%. Their conclusions about the big bang are consistent overall with the picture of cosmic evolution that has emerged from many other lines of evidence (but add some tantalizing hints of mystery: their measurement of the current rate of expansion as 67.5 +- 1.7 km/second/megaparsec is actually a tad smaller than the currently favored value). The amazing power of the technique is that it gives a snapshot of the universe at this era, and that it relies on completely different data from those used by other studies that rely on supernova or cosmic background radiation.

"The Clustering of Galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: Measuring DA and H at z = 0.57 from the Baryon Acoustic Peak in the Data Release 9 Spectroscopic Galaxy Sample," Lauren Anderson et al., MNRAS 439, 83, 2014.

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Wednesday, April 09, 2014

Chance Meeting Creates Celestial Diamond Ring

The planetary nebula Abell 33 captured using ESO's Very Large Telescope
The planetary nebula Abell 33 in the constellation of Hydra
Wide-field view of the sky around Abell 33



Zooming in on the planetary nebula Abell 33
Zooming in on the planetary nebula Abell 33

Panning across the planetary nebula Abell 33
Panning across the planetary nebula Abell 33

Astronomers using ESO’s Very Large Telescope in Chile have captured this eye-catching image of planetary nebula PN A66 33 — usually known as Abell 33. Created when an aging star blew off its outer layers, this beautiful blue bubble is, by chance, aligned with a foreground star, and bears an uncanny resemblance to a diamond engagement ring. This cosmic gem is unusually symmetric, appearing to be almost circular on the sky.

Most stars with masses similar to that of our Sun will end their lives as white dwarfs — small, very dense, and hot bodies that slowly cool down over billions of years. On the way to this final phase of their lives the stars throw their atmospheres out into the space and create planetary nebulae, colourful glowing clouds of gas surrounding the small, bright stellar relics.

This image, captured by ESO’s Very Large Telescope (VLT), shows the remarkably round planetary nebula Abell 33, located roughly 2500 light-years from Earth. Being perfectly round is uncommon for these objects — usually something disturbs the symmetry and causes the planetary nebula to display irregular shapes [1].

The strikingly bright star located along the rim of the nebula creates a beautiful illusion in this VLT image. This is just a chance alignment — the star, named HD 83535, lies in the foreground of the nebula, between Earth and Abell 33, in just the right place to make this view even more beautiful. Together, HD 83535 and Abell 33 create a sparkling diamond ring.

The remnant of Abell 33’s progenitor star, on its way to becoming a white dwarf, can be seen just slightly off-centre inside the nebula, visible as a tiny white pearl. It is still bright — more luminous than our own Sun — and emits enough ultraviolet radiation to make the bubble of expelled atmosphere glow [2].

Abell 33 is just one of the 86 objects included in astronomer George Abell's 1966 Abell Catalogue of Planetary Nebulae. Abell also scoured the skies for galaxy clusters, compiling the Abell Catalogue of over 4000 of these clusters in both the northern and southern hemispheres of the sky.

This image uses data from the FOcal Reducer and low dispersion Spectrograph (FORS) instrument attached to the VLT, which were acquired as part of the ESO Cosmic Gems programme [3].


[1] For example, the way the star spins, or if the central star is one component of a double or multiple star system.

[2] In this very sharp image the central star appears to be double. Whether this is a real association or just a chance alignment is not known.

[3] The ESO Cosmic Gems programme is an outreach initiative to produce images of interesting, intriguing or visually attractive objects using ESO telescopes, for the purposes of education and public outreach. The programme makes use of telescope time that cannot be used for science observations. All data collected may also be suitable for scientific purposes, and are made available to astronomers through ESO’s science archive.

More information

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”.



Richard Hook
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591

Source: ESO

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