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European Southern Observatory(Wikipedia)


European Southern Observatory

From Wikipedia, the free encyclopedia
"ESO" redirects here. For other uses, see ESO (disambiguation).
European Southern Observatory

Reaching New Heights in Astronomy

The participating countries
Formation1962
TypeIntergovernmental organisation
Purpose/focusResearch organization forastronomy
HeadquartersGarching, Germany
Membership15 (14 European states + Brazil)
Director GeneralTim de Zeeuw
Websitewww.eso.org
The European Southern Observatory (ESO; formally the European Organization for Astronomical Research in the Southern Hemisphere) is an intergovernmental research organisation for astronomy, supported by fifteen countries. Created in 1962, ESO has provided astronomers with state-of-the-art research facilities and access to the southern sky. The organisation employs around 730 staff members and receives annual member state contributions of approximately 143 million Euros.[1]

ESO has built and operated some of the largest and most technologically advanced telescopes in the world. These include the New Technology Telescope (NTT) that pioneered active optics technology, and the Very Large Telescope (VLT), consisting of four 8-metre class telescopes and four 1.8-metre Auxiliary Telescopes. Currently on-going ESO projects include the Atacama Large Millimeter Array (ALMA) and the European Extremely Large Telescope (E-ELT).
ALMA is a revolutionary facility for the observation of the Universe in the millimeter/submillimetre range of radiation and is the largest ground-based astronomy project in existence. Its construction is well under way, being scheduled to be completed in 2013. The ALMA project is an international collaboration between Europe (represented by ESO), East Asia, North America and the Republic of Chile.[2] [3]
The E-ELT is a 40-metre class telescope that is currently in detailed design phase phase and will be the world's largest optical/near-infraredtelescope. The light-gathering power of this telescope will allow detailed studies of planets around other stars, the first objects in theUniverse, super-massive black holes, and the nature and distribution of the dark matter and dark energy which dominate the Universe. ESO has been working together with its user community of European astronomers and astrophysicists to define this new giant telescope since the end of 2005.[4]
ESO's observing facilities have made important astronomical discoveries and produced several astronomical catalogues.[5] Recent findings include the discovery of the farthest gamma-ray burst and the evidence for a black hole at the centre of our galaxy, the Milky Way.[6][7] In 2004, the VLT allowed astronomers to obtain the first picture of an extrasolar planet, 2M1207b, orbiting a brown dwarf 173 light-years away.[8]The High Accuracy Radial Velocity Planet Searcher (HARPS) instrument, installed in another ESO telescope, led to the discovery of many other extrasolar planets, including Gliese 581c, one of the smallest planets outside the Solar System found to date.[9]

Contents

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[edit]History

ESO Directors General[10]
Otto Heckmann1962–1969
Adriaan Blaauw1970–1974
Lodewijk Woltjer1975–1987
Harry van der Laan1988–1992
Riccardo Giacconi (Nobel Prize winner)1993–1999
Catherine Cesarsky1999–2007
Tim de Zeeuwfrom 2007
The idea that European astronomers should establish a common large observatory arose at the Leiden Observatory in the Netherlands in the spring of 1953 between Walter Baade and Jan Oort.[11] It was quickly followed up by Oort who, on the 21st of June of the same year, gathered a group of astronomers in Leiden to consider it. Immediately thereafter, the subject was further discussed at the Groningen conference, also in the Netherlands. On the 26th of January 1954, an ESO declaration was signed by leading astronomers from six European countries expressing the wish that a joint European observatory be established in the southern hemisphere.[12]
The choice of the southern hemisphere resulted from the need to observe the southern sky. At the time, all large reflector telescopes (with an aperture of 2 metres or more) were located in the northern hemisphere. In addition, some of the most interesting objects of research, such as the central parts of the Milky Way and the Magellanic Clouds, were accessible only from the southern hemisphere.[13] The telescopes were to be set up in South Africa, where several European observatories were located, but it was discovered (after testing observing conditions over the years of 1955 to 1963) that the Andes were preferable. On the 15th of November 1963, Chile was chosen as the site for ESO's observatory.[14]
This decision was preceded by the ESO Convention, which was signed on the 5th of October 1962 by Belgium, Germany, France, the Netherlands and Sweden, and by the nomination (on the 1st of November 1962) of Otto Heckmann as the first Director General of the organisation. A first proposal for the Convention, between astronomy organisations in these five countries, was drafted in 1954. Although some amendments were made in the initial document, the matter of the Convention proceeded slowly until 1960, when it came into focus in that year's Committee meeting. The new draft was discussed in detail and one of the members, Bannier (who was also a member of the Council of CERN, the European Organisation for Nuclear Research), highlighted the need to have a Convention between governments and not only between organisations.[15]
The matter of the Convention, and the involvement of governments in it, became pressing because the costs of site testing expeditions were rising sharply. The final 1962 text was largely adopted from the CERN Convention because of the similarities between the two organisations and because some of the members of the ESO Council were also members of the Council of CERN.[16]
In 1966, the first of ESO's telescopes at the La Silla site in Chile began operating.[17] Because CERN, like ESO, developed powerful and sophisticated instrumentation, the astronomy organisation frequently turned to the nuclear research body for informal consultation. Eventually, a collaborative agreement between ESO and CERN was signed in 1970. A few months after, ESO's Telescope Division had established itself in a CERN building in Geneva. ESO's Sky Atlas Laboratory was also established on CERN premises.[18] ESO's European departments moved into the new ESO Headquarters in Garching near Munich, Germany in 1980.

[edit]Member states

Member countryJoined
 Belgium1962
 Germany1962
 France1962
 Netherlands1962
 Sweden1962
 Denmark1967
 Switzerland1981
 Italy1982, 24 May
 Portugal2000, 27 June
 United Kingdom2002, 8 July
 Finland2004, 1 July
 Spain2006, 1 July
 Czech Republic2007, 1 January
 Austria2008, 1 July
 Brazil2010, 29 December (Formal accession agreement)

[edit]ESO's Observing Sites in Chile

ESO Headquarters in Garching
While ESO's headquarters are located in Germany, all of its telescopes and observatories are in the north of Chile, where the organisation operates some of the world's largest and most advanced ground-based astronomical facilities:
These are among the best locations for astronomical observations in the southern hemisphere.[19]
One of the most ambitious ESO projects is the European Extremely Large Telescope (E-ELT), a 40-metre-class telescope based on an innovative 5-mirror design, following the concept of the formerly planned Overwhelmingly Large Telescope. The E-ELT will be the largest optical/near-infrared telescope in the world. ESO started the design phase of this telescope in early 2006 and aims to begin constructing it in 2012.[20] As decided by the ESO Council on the 26th of April 2010, a fourth site, Cerro Armazones, is to be the home of E-ELT.[21][22][23]
Each year, about 2000 proposals are made for the use of ESO telescopes, requesting between four and six times more nights than are available. The science done with these instruments annually results in a significant number of peer-reviewed publications. In 2009 alone, more than 650 refereed papers based on ESO data were published.[24]
ESO Telescopes[25]
NameSizeTypeLocation
Very Large Telescope (VLT)4 x 8.2 m + 4 x 1.8 moptical, near- and mid-infrared telescope arrayParanal
New Technology Telescope (NTT)3.58 moptical and infrared telescopeLa Silla
ESO 3.6 m telescope3.57 moptical and infrared telescopeLa Silla
MPG/ESO 2.2 m telescope2.20 moptical and infrared telescopeLa Silla
Atacama Pathfinder Experiment (APEX)12 mmillimetre-/submillimetre-wavelength telescopeChajnantor
Atacama Large Millimeter/submillimeter Array(ALMA)50 x 12 m, and 12 x 7 m + 4 x 12 m (ACA)[26]millimetre-/submillimetre-wavelength interferometer array telescopeChajnantor
Visible and Infrared Survey Telescope for Astronomy (VISTA)4.1 mnear-infrared survey telescopeParanal
VLT Survey Telescope (VST)2.6 moptical survey telescopeParanal
European Extremely Large Telescope (E-ELT)39.3 moptical to mid-infrared telescopeCerro Armazones (in detailed design phase)[27]
ESO's telescopes generate vast amounts of data at a high rate, which are stored in a permanent Science Archive Facility at ESO's headquarters. The archive now contains more than 1.5 million images or spectra with a total volume of about 65 terabytes (65,000,000,000,000 bytes) of data.
ESO also hosts the European Coordinating Facility for the Hubble Space Telescope (HST). This space-based observatory is a long-term collaboration between ESA and NASA. The observations are carried out in visible, infrared and ultraviolet light. In many ways Hubble has revolutionised modern astronomy, by not only being an efficient tool for making new discoveries, but also by driving astronomical research in general.[28][29]
Additional ESO research facilities are located in Santiago, Chile. The space includes a library, computing resources, and programmes for visiting scientists. ESO also maintains close ties with other observatories and universities throughout the country.
La Silla at night
La Silla Telescopes

[edit]La Silla

Main article: La Silla Observatory
La Silla, located in the southern part of the Atacama desert, 600 km north of Santiago de Chile and at an altitude of 2400 metres, is the home of ESO's original observing site. Like other observatories in this geographical area, La Silla is located far from sources of light pollution and it has one of the darkest night skies on the Earth. In La Silla, ESO currently operates three major telescopes: the 3.6-metre Telescope, the New Technology Telescope (NTT), and the 2.2-metre Max-Planck-ESO Telescope.
Moreover, the observatory regularly hosts visitor instruments that are attached to a telescope for the duration of a run of observation and are removed thereafter. La Silla also hosts national telescopes, such as the 1.2-metre Swiss Telescope and the 1.5-metre Danish Telescope.
About 300 refereed publications per year are attributable to the work of the observatory; moreover, scientific discoveries done with La Silla telescopes include several 'firsts'. The HARPS spectrograph detected the system around Gliese 581, which contains what may be the first known rocky planet in a habitable zone, outside the Solar System.[30] Several telescopes at La Silla played a crucial role in linking gamma-ray bursts—the most energetic explosions in the Universe since the Big Bang —with the explosions of massive stars. Since 1987, the ESO La Silla Observatory has also played an important role in the study and follow-up of the nearest recent supernova, SN 1987A .

[edit]ESO 3.6-metre Telescope

Main article: ESO 3.6 m Telescope
This telescope started operations in 1977 and set Europe the challenge of constructing and operating a 3–4-metre class telescope in the southern hemisphere. Over the years, it has been constantly upgraded, including the installation of a new secondary mirror that has kept the telescope in its place as one of the most efficient and productive engines of astronomical research.[31]
This conventionally designed horseshoe mount telescope, was mostly used for infrared spectroscopy. It now hosts the HARPS spectrograph, which is used for the search of extra-solar planets and for asteroseismology. The instrument is built to obtain very high long term radial velocity accuracy (on the order of 1 m/s).[32]
The Swedish ESO Submillimetre Telescope (SEST) at La Silla

[edit]New Technology Telescope (NTT)

The New Technology Telescope (NTT)
Main article: New Technology Telescope
The New Technology Telescope (NTT) is an alt-azimuth, 3.58-metre, Ritchey-Chrétien telescope inaugurated in 1989, the first in the world to have a computer-controlled main mirror. This mirror is flexible and its shape is actively adjusted during observations to preserve the optimal image quality. The secondary mirror position is also actively controlled in three directions. This technology, developed by ESO and known as active optics, is now applied to all major modern telescopes, such as the VLT and the future E-ELT.
The design of the octagonal enclosure housing the NTT is another technological breakthrough. The telescope dome is relatively small, and is ventilated by a system of flaps that makes air flow smoothly across the mirror, reducing turbulence and leading to sharper images.[33]

[edit]MPG/ESO 2.2-metre Telescope

Main article: MPG/ESO telescope
The 2.2-metre Telescope has been in operation at La Silla since early 1984 and is on indefinite loan to ESO from the Max Planck Society (Max-Planck-Gesellschaft or MPG in German). Telescope time is shared between MPG and ESO observing programmes, while the operation and maintenance of the telescope are ESO’s responsibility.
Its instrumentation includes the 67-million pixel Wide Field Imager (WFI) with a field of view as large as the full Moon,[34] which has taken many amazing images of celestial objects. Other instruments used are GROND, the Gamma-Ray Burst Optical/Near-Infrared Detector, which chases the afterglows of the most powerful explosions in the Universe, known as gamma-ray bursts,[35] and the high-resolution spectrograph FEROS (the Fiber-fed Extended Range Optical Spectrograph), used to make detailed studies of stars.

[edit]Other telescopes

La Silla also hosts several national and project telescopes that are not operated by ESO. Among them, are: the Swiss 1.2-metre Euler Telescope, the Danish 1.54-metre Telescope, as well as the REM and the TAROT telescopes.[36]
The Euler Telescope is a 1.2-metre telescope built and operated by the Observatory of Geneva (Switzerland). It is used to conduct high-precision radial velocity measurements that mainly serve to search for large extrasolar planets in the southern celestial hemisphere. Its first success was the discovery of a planet in orbit around Gliese 86.[37] Other observing programmes focus on variables stars, asteroseismology, follow-up of gamma-ray bursters (GRB), monitoring of active galactic nuclei (AGN) and gravitational lenses.
The 1.54-metre Danish telescope was built by Grubb-Parsons, and has been in use at La Silla since 1979. The telescope has an off-axis mount and the optics are of a Ritchey-Chrétien design. On account of the telescope's mount and the limited space inside the dome, the telescope has significant pointing restrictions.[38]
The Rapid Eye Mount Telescope (REM) is a small rapid-reaction automatic telescope with a primary mirror of 60 centimetre, in an alt-azimuth mount that started operations in October 2002. The main purpose of telescope is to follow the prompt afterglow of the GRBs detected by the NASA Swift satellite.[39][40]
The TAROT (Télescope à Action Rapide pour les Objets Transitoires, Rapid Action Telescope for Transient Objects) is a very fast moving (1 second) optical robotic telescope able to observe from the beginning of a gamma-ray burst (GRB). Satellites detecting GRBs send timely signals to TAROT, which in turn is able to give a sub-arc second position to the astronomical community. The data from the TAROT telescope are also useful to study the evolution of GRBs, the physics of the fireball and of the surrounding material.[41]

[edit]Paranal

Main article: Paranal Observatory
The Very Large Telescope (VLT)
The VLT´s Laser Guide Star
360-degree night panorama from Paranal
The Paranal Observatory is located on top of Cerro Paranal, in the Atacama Desert, in the northern part of Chile. Cerro Paranal is a 2,635-metre high mountain, located about 120 km south of the town of Antofagasta and 12 km inland from the Pacific coast.[42]
Paranal Observatory has three major telescopes operating in the visible and infrared light: the Very Large Telescope (VLT, four 8.2-metre Unit Telescopes, plus four 1.8-metre Auxiliary Telescopes), the VLT Survey Telescope (VST, 2.6 metres in diameter), and the Visible and Infrared Survey Telescope for Astronomy (VISTA, 4.1 metres in diameter).[43]
Additionally, in March 2008, Paranal was the location for the filming of several scenes in the 22nd James Bond movie, Quantum of Solace.[44][45]

[edit]Very Large Telescope

Main article: Very Large Telescope
The main facility at Paranal is the VLT. It is an optical/near and mid-infrared telescope consisting of four near-identical 8.2-metre Unit Telescopes (UTs), each hosting two or three instruments. These large telescopes can also work together, in groups of two or three, to form a giant 'interferometer', the ESO Very Large Telescope Interferometer or VLTI, allowing astronomers to see details up to 25 times finer than those seen with the individual telescopes. The light beams are combined in the VLTI using a complex system of mirrors located in underground tunnels where the light paths must be kept equal to distances less than 1/1000 mm over a hundred metres. With this kind of precision, the VLTI can achieve an angular resolution of milliarcseconds, equivalent to distinguishing the two headlights of a car at the distance of the Moon.[46]
The first of the UTs had its first light in May 1998 and was offered to the astronomical community on the 1st of April 1999. The other telescopes followed suit in 1999 and 2000, thus making the VLT fully operational. Four 1.8-metre Auxiliary Telescopes (ATs) have been added to the VLTI to make it available when the UTs are being used for other projects. These ATs were installed between 2004 and 2007.
Results from the VLT have led to the publication of an average of more than one peer-reviewed scientific paper per day. For instance, only in 2007, almost 500 refereed scientific papers were published based on VLT data.[47] The VLT's scientific discoveries include imaging an extrasolar planet for the first time,[48] tracking individual stars moving around the supermassive black hole at the centre of the Milky Way,[49]and observing the afterglow of the furthest known gamma-ray burst.[50]
[edit]Mapuche names for the Unit Telescopes
It had long been ESO's intention to provide "real" names to the four VLT Unit Telescopes, to replace the original, somewhat dry and technical designations of UT1 to UT4. In March 1999, at the time of the Paranal inauguration, four meaningful names of objects in the sky in the Mapuche language were chosen. This indigenous people lives mostly south of Santiago de Chile.
An essay contest was arranged in this connection among schoolchildren of the Chilean II Region of which Antofagasta is the capital to write about the implications of these names. It drew many entries dealing with the cultural heritage of ESO's host country.
The winning essay was submitted by 17-year old Jorssy Albanez Castilla from Chuquicamata, near the city of Calama. She received the prize, an amateur telescope, during the Paranal Inauguration.[51]
The four Unit Telescopes are now known as:[52]
  • Antu (UT1; The Sun)
  • Kueyen (UT2; The Moon)
  • Melipal (UT3; The Southern Cross)
  • Yepun (UT4; Venus—as evening star)
Originally translated as "Sirius", it now seems that "Yepun" actually means "Venus".[53]

[edit]Survey Telescopes

Visible and Infrared Survey Telescope for Astronomy (VISTA)[54] is housed on the peak adjacent to the one hosting the VLT and shares the same exceptional observing conditions. VISTA’s main mirror is 4.1 metres across and is the most highly curved mirror of this size and quality ever made—its deviations from a perfect surface are less than a few thousandths of the thickness of a human hair—and its construction and polishing presented formidable challenges.[55]
VISTA was conceived and developed by a consortium of 18 universities in the United Kingdom led by Queen Mary, University of London and became an in-kind contribution to ESO as part of the UK's accession agreement. The telescope design and construction were project-managed by the Science and Technology Facilities Council's UK Astronomy Technology Centre (STFC, UK ATC). Provisional acceptance of VISTA was formally granted by ESO at a ceremony at ESO's Headquarters in Garching, Germany, attended by representatives of Queen Mary, University of London and STFC, on 10 December 2009. Since then, the telescope has been operated by ESO.[56], also capturing stunning images since it started operating.[57][58]
The VLT Survey Telescope (VST) is a state-of-the-art 2.6-metre telescope equipped with OmegaCAM, a 268 megapixel CCD camera with a field of view four times the area of the full Moon. It complements VISTA as it will survey the sky in the visible light. The VST is the result of a joint venture between ESO and the Astronomical Observatory of Capodimonte, Naples, a research centre of the Italian National Institute for Astrophysics INAF. The VST became operational in 2011.[59][60]
The scientific goals of both surveys range from the nature of dark energy to the threat of near-Earth asteroids. Large teams of astronomers throughout Europe will conduct the surveys. Some of them will cover most of the southern sky while others will focus on smaller areas.
Both VISTA and the VST are expected to produce huge quantities of data given that a single picture taken by VISTA has 67 megapixels and images from OmegaCam on the VST will have 268 megapixels. The two Survey Telescopes will produce far more data every night than all the other instruments on the VLT together. The VST and VISTA will produce more than 100 Terabytes of data per year.[61]

[edit]Llano de Chajnantor

Main article: Llano de Chajnantor Observatory
The APEX 12-metre submillimetre telescope
Three ALMA antennas close together on Chajnantor
An ALMA antenna en route to the Chajnantor plateau
The Llano de Chajnantor is a 5,100-metre high plateau in the Chilean Atacama Desert, about 50 kilometres east of San Pedro de Atacama. The site is 750 metres higher than the observatories on Mauna Kea and 2400 metres higher than the VLT in Cerro Paranal.
It is a very dry place—inhospitable to humans—but an excellent site for submillimetre astronomy.Water vapor molecules in Earth's atmosphere absorb and attenuate submillimetre radiation and thus a dry site is required for this type of radio astronomy.
The telescopes that can be found here are:
APEX and ALMA are telescopes designed for millimetre and submillimetre astronomy. This type of astronomy is a relatively unexplored frontier and reveals a Universe that cannot be seen in the more familiar visible or infrared light. It is ideal for studying the "cold Universe": light at these wavelengths shines from vast cold clouds in interstellar space, at temperatures only a few tens of degrees above absolute zero. Astronomers use this light to study the chemical and physical conditions in these molecular clouds —the dense regions of gas and cosmic dust where new stars are being born. Seen in visible light, these regions of the Universe are often dark and obscured due to the dust, but they shine brightly in the millimetre and submillimetre part of the electromagnetic spectrum. This wavelength range is also ideal for studying some of the earliest and most distant galaxies in the Universe, whose light has been redshifted into these longer wavelengths [62][63], as an effect of the expansion of the Universe.

[edit]Atacama Pathfinder Experiment (APEX)

The Atacama Pathfinder Experiment telescope is operated by ESO in collaboration with the Max Planck Institute for Radio Astronomy (Bonn,Germany) and the Onsala Space Observatory (Onsala, Sweden). It is a 12-metre diameter telescope, the largest of its kind working in the southern hemisphere, operating at millimetre and submillimetre wavelengths—a range if radiations between infrared light and microwaves .[64]
APEX also serves as a pathfinder for ALMA, the Atacama Large Millimeter Array, a revolutionary astronomical interferometer that ESO, together with its international partners, is now building on the Chajnantor plateau. APEX is based on a prototype ALMA antenna, modified to be operated as single dish radio telescope.

[edit]Atacama Large Millimeter/submillimeter Array (ALMA)

Main article: Atacama Large Millimeter Array
ALMA is an astronomical interferometer of revolutionary design initially composed of 66 high-precision antennas, and operating at wavelengths of 0.3 to 3.6 mm. Its main array will have fifty 12-metre antennas, acting together as a single telescope—an interferometer. An additional compact array of four 12-metre and twelve 7-metre antennas will complement this. The antennas can be spread across the desert plateau over distances from 150 metres to 16 kilometres, which will give ALMA a powerful variable "zoom"—watch a video of an ALMA transporter to see how the antennas are moved. ALMA will be able to probe the Universe at millimeter and submillimeter wavelengths with unprecedented sensitivity and resolution, with a vision up to ten times sharper than the Hubble Space Telescope, and complementing images made with the VLT Interferometer.[65] ALMA results from a collaboration between East Asia (Japan and Taiwan), Europe (ESO), North America (USA and Canada), and Chile.
Science goals of ALMA include studying the origins and formation of stars, galaxies, and planets, with observations of molecular gas and dust, distant galaxies towards the edge of the observable Universe, and the relic radiation of the Big Bang.[66] The release of the call for ALMA science proposals happened on 31 March 2011[67] with observations expected to start in October 2011.[68]

[edit]Science with ESO Telescopes: Fields of Research and Greatest Discoveries

[edit]The search for planets outside our Solar System

Icy exoplanet (Artist's impression)
"Is there life elsewhere in the Universe?" possibly is one of the Mankind's most profound —and still unanswered— questions. A key step of the human attempt to answer this question is the search for planets outside the Solar System. ESO's observatories are equipped with a unique arsenal of instruments for finding, studying and monitoring these so-called exoplanets. In 2004, the Very Large Telescope detected the faint glow of what seemed to be a planet orbiting a star located some 200 light-years away from the Earth. A year after, in 2005, this detection was confirmed to be the first picture of an exoplanet ever. Although this planet is a giant one, some five times more massive than Jupiter, this observation marks a first major step towards the characterization of the physical structure and chemical composition of exoplanets.[69][70]
In spite of the fact that planets seem to be very common in the Universe, they are extremely tiny and faint objects at cosmic scales. This makes their direct detection very difficult, with the current technology. For this reason, most of the exoplanets discovered so far have been detected with indirect methods. Among these methods, the most successful has been the radial velocity method. HARPS, the High Accuracy Radial velocity Planet Searcher, has allowed the discovery of a significant number of planets with masses below that of Neptune, orbiting a nearby stars. Few of these planets are among the smallest ever discovered or reside in its star's habitable zone. Particularly, it exists the possibility that one of these planets is covered by oceans—a waterworld. This discovery marks a groundbreaking result in the search for planets that could support life.[71]
Finally, in the framework of three different global campaigns, the Danish 1,54-metre Telescope at La Silla participated in the discovery of one of the most Earth-like planets found so far. The planet, detected using the microlensing technique, is only about five times as massive as the Earth, circles its parent star in about 10 years, and most certainly has a rocky/icy surface.[72]

[edit]The determination of the age of the Universe

The Globular Cluster 47 Tuc
By using the Very Large Telescope, astronomers have carried out an independent determination of the age of the Universe and have thrown new light on the earliest stages of our Milky Way. They measured for the first time the amount of the radioactive isotope uranium-238 in a star that was born when the Milky Way, the galaxy in which we live, was still forming.[73]
Like carbon dating in archaeology, but over even longer timescales, this uranium 'clock' measures the age of the star. It shows that the star is 12.5 billion years old. Since the star cannot be older than the Universe itself, the Universe must be even older than this. This agrees with what we know from cosmology, which gives an age of the Universe of 13.7 billion years. The star, and our galaxy, must have formed very soon after the Big Bang.[74]
Another result is the first ever measurement of the beryllium content of two stars, in a globular cluster in the Milky Way. With this measurement, astronomers found that the first generation of stars in our galaxy must have formed soon after the end of the ~200 million-year long 'Dark Ages' that followed the Big Bang.[75]

[edit]A black hole at the centre of our galaxy

What lies at the center of the Milky Way? For a long time, astronomers have suspected that a black hole lurks at the heart of our galaxy, but could not be sure. A conclusive evidence was obtained after 16 years of regular monitoring of the Galactic Centre with ESO telescopes at La Silla and Paranal Observatories.
Stars at the centre of the Milky Way are so densely packed that special imaging techniques such as adaptive optics were needed to boost the resolution of the VLT. Thanks to this, astronomers were able to watch individual stars with unprecedented accuracy as they moved around the galactic centre.[76] Their paths conclusively showed that they must be orbiting in the immense gravitational grip of a supermassive black hole, almost three million times more massive than the Sun.[77] The VLT observations also revealed flashes of infrared light emerging from the region at regular intervals. Whilst the exact cause of this phenomenon remains unknown, observers have suggested the black hole may be spinning rapidly. Whatever is happening, the black hole's life is not all peace and quiet. [78]
The VLT has also been used to peer into the centres of galaxies beyond our own, where clear signs of activity produced by supermassive black holes are found.[79] In the active galaxyNGC 1097, a complex network of filaments spiralling from the main part of the galaxy down to the centre was seen with extraordinary detail.[80]

[edit]Gamma-ray bursts

Gamma-ray bursts (GRBs) are bursts of highly energetic gamma rays lasting from less than a second to several minutes—the blink of an eye on cosmological timescales. They are known to occur at huge distances from Earth, towards the limits of the observable Universe.
The VLT has observed the afterglow of a gamma-ray burst that is the farthest known. With a measured redshift of 8.2, the light from this very remote astronomical source has taken more than 13,000 million years to reach us. It is thus seen when the Universe was less than 600 million years old, or less than five per cent its present age. It must have released 300 times as much energy in a few seconds as the Sun will in its entire lifetime of more than 10,000 million years. GRBs are therefore the most powerful explosions in the Universe since the Big Bang.[81]
The nature of these explosions has remained a mystery for a long time. Observations show that GRBs come in two types—short-duration (shorter than a few seconds), and long-duration—and it was suspected that two different kinds of cosmic event caused them. In 2003, ESO telescopes played a key role in following the aftermath of an explosion for a whole month. The observations showed that the light had similar properties to that from a supernova. This fact allowed astronomers linking long-duration GRBs with the ultimate explosions of massive stars, known as 'hypernovae'. [82] In 2005, ESO telescopes detected, for the first time, the visible light following a short-duration burst and tracked this light for three weeks. This time, the conclusion was that the short-duration bursts could not be caused by a hypernova. Instead, it is thought that they originate in the violent mergers of neutron stars or black holes.[83]Observations of gamma-ray burst afterglows were also coordinated between the VLT and the Atacama Pathfinder Experiment (APEX) in order to identify the possible counterpart and its decay at submillimeter wavelengths.[84]

[edit]Science archive and the digital universe

ESO Science Archive
The Science Archive Operation Group receives and redistributes ESO and HST data and provides front-line archive user support. About 12 Terabytes (TB) of public data are distributed per year through the ESO archive, following about 10,000 web requests. Additionally, more than 2,000 CDs and DVDs of proprietary data are sent out annually to their respective Principal Investigators for observations made in service mode. The current total archive holding is about 65 TB, with an input rate of about 15 TB per year. This is being drastically increased by a factor of 10 or so due to the Survey Telescopes' data production rate.
Major breakthroughs in telescope, detector, and computer technology now allow astronomical surveys to produce massive amounts of images, spectra, and catalogues. These datasets cover the sky at all wavelengths from gamma- and X-rays, through optical and infrared, to radio waves. Astronomers are developing ways to do new science, by making the huge amount of data in this 'digital Universe' easily accessible. These techniques use the so-called grid paradigm of distributed computing, with seamless and transparent access to the data through 'Virtual Observatories' (VOs). Just as a physical observatory has telescopes, each with unique astronomical instruments, a VO consists of data centres, each with unique collections of astronomical data, soft-ware systems and processing capabilities. This global, community-based initiative is being developed world-wide under the auspices of the International Virtual Observatory Alliance[85] and in Europe under the framework of the EURO-VO project.[86]
VOs have already proved their effectiveness, for example by discovering 31 new optically faint, obscured quasar candidates in the existing Great Observatories Origins Deep Survey(GOODS) fields, quadrupling the number previously found. The discovery means that surveys of powerful supermassive black holes have so far underestimated their numbers by at least a factor of two, and possibly by up to a factor of five.[87]

[edit]ESO's top 10 astronomical discoveries

ESO Top 10 Astronomical Discoveries
Planetary system Gliese 581 (Artist's impression)
The most distant Gamma-ray burst (Artist's impression)
1. Stars orbiting the Milky Way black hole
Several of ESO's flagship telescopes were used in a 16-year long study to obtain the most detailed view ever of the surroundings of the monster lurking at the heart of our galaxy,[88]—a supermassive black hole.[89]
2. Accelerating Universe
Two independent research teams have shown that the expansion of the Universe is accelerating—based on observations of exploding stars with astronomical telescopes at La Silla [90]. The research teams where awarded the 2011 Nobel Prize in Physics for said discovery. [91]
3. First image of an exoplanet
The VLT has obtained the first-ever image of a planet outside our Solar System. The 5-Jupiter-mass planet orbits a failed star—abrown dwarf—at a distance of 55 times the mean Earth-Sun distance. [92]
4. Gamma-ray bursts—the connections with supernovae and merging neutron stars
ESO telescopes have provided definitive proof that long gamma-ray bursts are linked with the ultimate explosion of massive stars; on the other hand, short gamma-ray bursts seem to be produced by merging neutron stars.[93]
5. Cosmic temperature independently measured
The VLT has detected for the first time carbon monoxide molecules in a galaxy located almost 11,000 million light-years away. This has allowed astronomers to obtain the most precise measurement of the cosmic temperature at such a remote epoch.[94]
6. Oldest star known in the Milky Way
Using ESO's VLT, astronomers have measured the age of the oldest star known in our galaxy, the Milky Way. At 13,200 million years old, the star was born in the earliest era of star formation in the Universe.[95]
7. Flares from the supermassive black hole at the centre of the Milky Way
The VLT and APEX teamed up to study the violent flares from the supermassive black hole at the centre of the Milky Way, revealing material being stretched out as it orbits in the intense gravity close to the central black hole.[96]
8. Direct measurements of the spectra of exoplanets and their atmospheres
The atmosphere around a super-Earth exoplanet has been analysed for the first time using the VLT. The planet, which is known as GJ 1214b, was studied as it passed in front of its parent star and some of the starlight passed through the planet’s atmosphere.[97]
9. Richest planetary system
Astronomers using ESO’s HARPS have discovered a planetary system containing at least five planets, orbiting the Sun-like star HD 10180. Also evidence that two other planets may be present, one of which would have the lowest mass ever found.[98]
10. Milky Way stellar motions
After more than 1000 nights of observations at La Silla, spread over 15 years, astronomers have determined the motions of more than 14,000 Sun-like stars residing in the neighbourhood of the Sun, showing that our home galaxy has led a much more turbulent and chaotic life than previously assumed.[99]

[edit]Outreach activities

ESOcast
Outreach activities are carried out by the ESO education and Public Outreach Department (ePOD). A wide range of programs and activities are used to meet the specific requirements of television, print and online media, such as press releases and broadcast material for the media. ePOD embraces a multimedia approach to public outreach, as seen in, ESO and Hubble's videocast (ESOcast and Hubblecast, respectively), Facebook pages, and other products. The Department also produces high-quality printed material such as brochures, books, annual reports, newsletters (Messenger, ST-ECF Newsletter, CAPjournal) posters, etc.[100]
In the past, events such as the International Year of Astronomy 2009 (IYA2009) (with IAU and UNESCO), VLT First Light, Astronomy On-line, and the S-L 9 impact, have come out of the Department. ePOD also organises educational campaigns (Venus Transit, Science on Stage and Science in School are past examples) and exhibitions.[101]
In addition, the ESO ePOD supports science communicators, and especially those communicating astronomy with the public through different products and activities. A range of useful tools and information is available in ePOD's astronomy communication resources website. A large collection of photos can be found in the ESO Public Image Gallery, while a series of products from educational material to press kits can be downloaded for free from the ePOD website or ordered in "physical form". ESO's multimedia that has accompanied press releases as well as video news releases and the ESOcast, is available from ESO's video library.
As part of the Department, European outreach for the NASA/ESA Hubble Space Telescope provides comprehensive information about this telescope and its scientific discoveries. The International Astronomical Union (IAU) Press Office is also hosted as part of ePOD.[102]

[edit]Press releases and other products

ESO press releases describe important scientific, technical and organisation developments and achievements, as well as results obtained by scientists using ESO facilities. The goal of these press releases is to share exciting discoveries and the beauty of the Universe with the general public.
ESO publishes three different types of press releases.[103] Science releases describe scientific results usually appearing in a peer-reviewed journal that involve data from ESO observatories or ESO staff. Organisation releases cover a range of themes related to ESO operations, including news on current and future observatories, new astronomical instruments, and announcements of exhibitions all over the world. Finally, ESO selects its best astronomical images and presents them to the public in periodic photo releases.
All press releases, dating back to 1985, are available online. There are also child-friendly versions[104] as well as press releases translated into the languages of ESO's member countries.
ESO also publishes Announcements[105] and Pictures of the Week[106] on its website. Announcements are shorter than press releases (typically below 200 words) and highlight stories and events which are of interest to the community. Pictures of the Week show beautiful or interesting photos from ESO telescopes, and can highlight recent events or archival photos. All former entries are available on the website.
ESOcast is a video podcast series dedicated to bringing the latest news and research from ESO—Astronomy made on planet Earth. Here the Universe's ultimate frontier is explored with Doctor J, also known as Dr. Joe Liske who is a German astronomer at ESO. His scientific interests are in cosmology, particularly on galaxy evolution and quasars.[107]

[edit]Gallery

These images are among the best ones from ESO Top 100 Images.
  • VISTA's infrared view of the Orion Nebula
  • The Helix Nebula
  • The Globular Cluster Omega Centauri
  • A 340-million pixel starscape from Paranal
  • NGC 2264 and the Christmas Tree cluster
  • The Centre of the Milky Way
  • NGC 2467 and Surroundings
  • The Horsehead Nebula
  • Messier 78: a reflection nebula in Orion
  • Panoramic view of the WR 22 and Eta Carinae regions of the Carina Nebula
  • The hidden fires of the Flame Nebula
  • Early morning on Paranal
  • The future ALMA array on Chajnantor (artist's rendering)
  • Rare 360-degree Panorama of the Southern Sky
  • 370-million-pixel starscape of the Lagoon Nebula
  • The Milky Way panorama
  • The Omega Nebula
  • Centaurus A
  • Glowing Stellar Nurseries
  • The R Coronae Australis region imaged with the Wide Field Imager at La Silla

[edit]See also

[edit]References

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  100. ^ "ESO Outreach". Retrieved 2011-05-05.
  101. ^ "ePOD exhibitions". Retrieved 2011-05-05.
  102. ^ "IAU Press Office". Retrieved 2011-05-05.
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  106. ^ "ESO Picture of the Week". Retrieved 2011-05-05.
  107. ^ "Joe Liske's home". Retrieved 2011-05-05.

[edit]External links

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