Green light for European Extremely Large Telescope construction

This artist’s impression shows the European Extremely Large Telescope (E-ELT) in its enclosure. The E-ELT will be a 39-metre aperture optical and infrared telescope sited on Cerro Armazones in the Chilean Atacama Desert, 20 kilometres from ESO’s Very Large Telescope on Cerro Paranal. It will be the world’s largest “eye on the sky”. Credit: ESO/L. Calçada

At a recent meeting ESO's main governing body, the Council* gave the green light for the construction of the European Extremely Large Telescope (E-ELT) in two phases. Spending of around one billion euros has been authorised for the first phase, which will cover the construction costs of a fully working telescope with a suite of powerful instruments and first light targeted in ten years time. It will enable tremendous scientific discoveries in the fields of exoplanets, the stellar composition of nearby galaxies and the deep Universe. The largest ESO contract ever, for the telescope dome and main structure, will be placed within the next year.

The E-ELT will be a 39-metre aperture optical and infrared telescope sited on Cerro Armazones in the Chilean Atacama Desert, 20 kilometres from ESO's Very Large Telescope on Cerro Paranal. It will be the world's largest "eye on the sky."

"The decision taken by Council means that the telescope can now be built, and that major industrial construction work for the E-ELT is now funded and can proceed according to plan. There is already a lot of progress in Chile on the summit of Armazones and the next few years will be very exciting," said Tim de Zeeuw, ESO's Director General.

The construction of the E-ELT was approved by ESO's Council in June 2012 under the condition that contracts with a value larger than 2 million euros could only be awarded once the total cost of the telescope (1083 million euros at 2012 prices) was funded to a 90% level. An exception was granted for the civil works at the site, which started with the groundbreaking ceremony in June 2014 and are making good progress.

For the time being, 10% of the overall project costs have been shifted to a second phase. With the accession of Poland to ESO, the current funding commitments to the E-ELT have now reached more than 90% of the total cost of the first phase that will bring a fully working E-ELT. Additional commitments from upcoming Member State Brazil are expected in the coming years.

To prevent the project from slipping, the ESO Council has decided that construction of the first phase of the 39-metre telescope can now proceed. This funded work includes the contract for the telescope's dome and main structure -- the largest in ESO's history -- which will be awarded in late 2015, and leads to the construction of a fully working E-ELT.

Telescope components that are not yet funded include parts of the adaptive optics system, some of the instrument work, the innermost five rings of segments of the telescope's main mirror (210 mirror segments) and a spare set of primary mirror segments needed for more efficient telescope operation in the future. The construction of these components, whose postponement does not reduce the extraordinary scientific achievements the telescope will already be able to accomplish at the end of phase one, will be approved as additional funding becomes available, including that expected from the upcoming Member State Brazil.

"The funds that are now committed will allow the construction of a fully working E-ELT that will be the most powerful of all the extremely large telescope projects currently planned, with superior light collecting area and instrumentation. It will allow the initial characterisation of Earth-mass exoplanets, the study of the resolved stellar populations in nearby galaxies as well as ultra-sensitive observations of the deep Universe," concludes Tim de Zeeuw.

*The decision needed ten positive votes (out of fourteen). Eleven positive votes were obtained. Three out of the fourteen votes are ad referendum votes, which means that they are to be considered as provisionally positive and are subject to confirmation by the authorities in these three Member States, before the next Council meeting.

Source: European Southern Observatory - ESO

A colorful gathering of middle-aged stars

The MPG/ESO 2.2-metre telescope at ESO's La Silla Observatory in Chile captured this richly colourful view of the bright star cluster NGC 3532. Some of the stars still shine with a hot bluish colour, but many of the more massive ones have become red giants and glow with a rich orange hue. Credit: ESO/G. Beccari

The MPG/ESO 2.2-metre telescope at ESO's La Silla Observatory in Chile has captured a richly colourful view of the bright star cluster NGC 3532. Some of the stars still shine with a hot bluish colour, but many of the more massive ones have become red giants and glow with a rich orange hue.

NGC 3532 is a bright open cluster located some 1300 light-years away in the constellation of Carina (The Keel of the ship Argo). It is informally known as the Wishing Well Cluster, as it resembles scattered silver coins which have been dropped into a well. It is also referred to as the Football Cluster, although how appropriate this is depends on which side of the Atlantic you live. It acquired the name because of its oval shape, which citizens of rugby-playing nations might see as resembling a rugby ball.

This very bright star cluster is easily seen with the naked eye from the southern hemisphere. It was discovered by French astronomer Nicolas Louis de Lacaille whilst observing from South Africa in 1752 and was catalogued three years later in 1755. It is one of the most spectacular open star clusters in the whole sky.

NGC 3532 covers an area of the sky that is almost twice the size of the full Moon. It was described as a binary-rich cluster by John Herschel who observed "several elegant double stars" here during hisstay in southern Africa in the 1830s. Of additional, much more recent, historical relevance, NGC 3532 was the first target to be observed by the NASA/ESA Hubble Space Telescope, on 20 May 1990.

This grouping of stars is about 300 million years old. This makes it middle-aged by open star cluster standards.* The cluster stars that started off with moderate masses are still shining brightly with blue-white colours, but the more massive ones have already exhausted their supplies of hydrogen fuel and have become red giant stars. As a result the cluster appears rich in both blue and orange stars. The most massive stars in the original cluster will have already run through their brief but brilliant lives and exploded as supernovae long ago. There are also numerous less conspicuous fainter stars of lower mass that have longer lives and shine with yellow or red hues. NGC 3532 consists of around 400 stars in total.

The background sky here in a rich part of the Milky Way is very crowded with stars. Some glowing red gas is also apparent, as well as subtle lanes of dust that block the view of more distant stars. These are probably not connected to the cluster itself, which is old enough to have cleared away any material in its surroundings long ago.

This image of NGC 3532 was captured by the Wide Field Imager instrument at ESO's La Silla Observatory in February 2013.

* Stars with masses many times greater than the Sun have lives of just a few million years, the Sun is expected to live for about ten billion years and low-mass stars have expected lives of hundreds of billions of years -- much greater than the current age of the Universe.

Source: European Southern Observatory - ESO