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Stars are the nuclear furnaces of the Universe in which chemical elements, including the building blocks of life, are synthesised and recycled: without stars there would be no life. Accordingly,stellar astrophysics has long been a core activity for astronomers. But much remains to be understood. With higher angular resolution and greater sensitivity astronomers will be able to observe the faintest, least massive stars,allowing us to close the current huge gap in our knowledge concerning star and planet formation. Nucleocosmochronometry — the radiocarbon-14 method as applied to stars — will become possible for stars right across the Milky Way, allowing us to study galactic prehistory by dating the very first stars. And some of the brightest stellar phenomena, including the violent deaths of stars in supernovae and gamma-ray bursts, will be traced out to very large distances, offering a direct map of the star formation history of the entire Universe.
The European Extremely Large Telescope (E-ELT) will be able to answer some of the most prominent open questions: What are the details of star formation, and how does this process connect with the formation of planets? When did the first stars form? What triggers the most energetic events that we know of in the Universe, the deaths of stars in gamma-ray bursts?
The term island universes was introduced in 1755 by Immanuel Kant, and used at the beginning of the 20th century to define spiral nebulae as independent galaxies outside the Milky Way. Trying to understand galaxy formation and evolution has become one of the most active fields of astronomical research over the last few decades, as large telescopes have reached out beyond the Milky Way.Yet, even nearby giant galaxies have remained diffuse nebulae that cannot be resolved into individual stars. The unique angular resolution of the E-ELT will revolutionise this field by allowing us to observe individual stars in galaxies out to distances of tens of millions of light-years. Even at greater distances, we will be able to make the kind of observations of the structure of galaxies and the motions of their constituent stars that previously have only been possible in the nearby Universe: by taking advantage of the finite speed of light, we can peer back in time to see how and when galaxies were assembled.
The European Extremely Large Telescope (E-ELT) will be able to answer some of the most prominent open questions: What stars are galaxies made of? How many generations of stars do galaxies host and when did they form? What is the star formation history of the Universe? When and how did galaxies as we see them today form? How did galaxies evolve through time?
The discovery that the expansion of the Universe has recently begun to accelerate, presumably driven by some form of dark energy, was arguably one of the most important as well as mysterious scientific break-throughs of the past decade.The E-ELT will help us to elucidate the nature of dark energy by helping to discover and identify distant type Ia supernovae. These are excellent distance indicators and can be used to map out space and its expansion history. In addition to this geometric method the E-ELT will also attempt, for the first time, to constrain dark energy by directly observing the global dynamics of the Universe: the evolution of the expansion rate causes a tiny time-drift in the redshifts of distant objects and the E-ELT will be able to detect this effect in the intergalactic medium. This measurement will offer a truly independent and unique approach to the exploration of the expansion history of the Universe.
The E-ELT will also search for possible variations over cosmic time of fundamental physical constants, such as the fine-structure constant and the proton-to-electron mass ratio. An unambiguous detection of such variations would have far-reaching consequences for unified theories of the fundamental interactions, for the existence of extra dimensions of space and/or time, and for the possibility of scalar fields acting in the late Universe.
The E-ELT will pursue a vigorous scientific programme of exploring the formation and evolution of galaxies in the high redshift Universe. Although a satisfactory scenario describing the hierarchical assembly of dark matter halos is now well established, our physical understanding of the build-up of the baryonic component of galaxies is only fragmentary and fundamentally incomplete. With the enormous sensitivity and resolution gains of the E-ELT we will be able to peer beyond our present horizons and uncover the physical processes that form and transform galaxies across cosmic time. The E-ELT will provide us with spatially resolved spectroscopic surveys of hundreds of massive galaxies all the way out to the redshifts of the most distant galaxies presently known, supplying us with the kind of detailed information on their stellar masses, ages, metallicities, star formation rates and dynamical states that is currently only available for low redshift galaxies.
The E-ELT will also push back to the crucial earliest stages of galaxy formation, right at the end of the dark ages, by identifying the galaxies responsible for the reionization of the Universe and by informing us of their basic properties. Through these observations the E-ELT will drive the transition from the current phenomenological models to a much more physical understanding of galaxy formation and evolution.
The E-ELT offers the exciting prospect of reconstructing the formation and evolution histories of a representative sample of galaxies in the nearby Universe by studying their resolved stellar populations.
Local Group of nearby galaxies. Andrew Z. Colvin
A galaxy’s stellar populations carry a memory of its entire star formation history, and decoding this information offers detailed insights into the galaxy’s past. However, studying stellar populations requires the capability of resolving and measuring individual stars and so up until now such studies have been limited to our own Galaxy and its nearest neighbours. In particular, no examples of large elliptical galaxies are within reach of current telescopes for this type of study.
With its superior resolution and photon collecting power the E-ELT will allow us to perform precise photometry and spectroscopy on the stellar populations of a much more representative sample of galaxies, reaching out to the nearest giant ellipticals at the distance of the Virgo cluster.
This deep image of the Virgo Cluster obtained by Chris Mihos and his colleagues using the Burrell Schmidt telescope shows the diffuse light between the galaxies belonging to the cluster. North is up, east to the left. The dark spots indicate where bright foreground stars were removed from the image. Messier 87 is the largest galaxy in the picture (lower left).
Thus, the E-ELT will provide detailed information on the star formation, metal enrichment and kinematic histories of nearby galaxies, showing us how they were formed and built-up over time.
Discovering and characterising planets and proto-planetary systems around other stars will be one of the most important and exciting aspects of the E-ELT science programme. This will include not only the discovery of planets down to Earth-like masses using the radial velocity technique but also the direct imaging of larger planets and possibly even the characterisation of their atmospheres.
The E-ELT will be capable of detecting reflected light from mature giant planets (Jupiter to Neptune-like) and may be able to probe their atmospheres through low resolution spectroscopy. It will also enable us to directly study planetary systems during their formation from proto-planetary discs around many nearby very young stars. Furthermore, observations of giant planets in young stellar clusters and star forming regions will trace their evolution as a function of age. Thus, the E-ELT will answer fundamental questions regarding planet formation and evolution, the planetary environment of other stars, and the uniqueness (or otherwise) of the Solar System and Earth.
This artist’s impression shows the magnetar in the very rich and young star cluster Westerlund 1. This remarkable cluster contains hundreds of very massive stars, some shining with a brilliance of almost one million suns. European astronomers have for the first time demonstrated that this magnetar — an unusual type of neutron star with an extremely strong magnetic field — probably was formed as part of a binary star system. The discovery of the magnetar’s former companion elsewhere in the cluster helps solve the mystery of how a star that started off so massive could become a magnetar, rather than collapse into a black hole. Credit: ESO/L. Calçada
May this holiday season sparkle and shine, may all of your wishes and dreams come true, and may you feel this happiness all year round. Wishing you much happiness today and throughout the New Year.
The E-ELT Admin team
NGC 5426 and NGC 5427 are two spiral galaxies of similar sizes engaged in a dramatic dance. It is not certain that this interaction will end in a collision and ultimately a merging of the two galaxies, although the galaxies have already been affected. Together known as Arp 271, this dance will last for tens of millions of years, creating new stars as a result of the mutual gravitational attraction between the galaxies, a pull seen in the bridge of stars already connecting the two. Located 90 million light-years away towards the constellation of Virgo (the Virgin), the Arp 271 pair is about 130 000 light-years across. It was originally discovered in 1785 by William Herschel. Quite possibly, our own Milky Way will undergo a similar collision in about five billion years with the neighbouring Andromeda galaxy, which is now located about 2.6 million light-years away from the Milky Way. This image was taken with the EFOSC instrument, attached to the 3.58-metre New Technology Telescope at ESO’s La Silla Observatory in Chile. The data were acquired through three different filters (B, V, and R) for a total exposure time of 4440 seconds. The field of view is about 4 arcminutes. Credit: ESO — with Abel Moreira.
Andromeda Galaxy via NASA/GALEX
A long exposure has captured the setting stars in a moonlit night in form of colorful star trails above La Silla telescope domes and inversion layer in the southern outskirts of the Atacama desert, Chile. The trails are notabely distorted at the horizon as seen in this telephoto view. This mirage is similar to other common mirage of astronomical object such as the moon or the sun when they are near the horizon; an optical phenomenon in which light rays are refracted and bent in the atmosphere to produce distorted or multiple images of the object. The European Southern Observatory’s (ESO) site at La Silla has telescopes which observe at optical and infrared. The largest optical telescope has a mirror with a diameter of 3.6 metres. The high altitude of La Silla (2400 metres), the dark sky, and the clear air above it (reducing atmospheric distortions of incoming light), make the site an ideal location for astronomical observations. Credit: ESO/B. Tafreshi (twanight.org)— with Abel Moreira.
An artist’s rendering of the European Extremely Large Telescope (E-ELT) in the Chilean Atacama Desert. In the distance, ESO’s Paranal Observatory sits atop the Cerro Paranal mountain.(You can grasp the dimension of the European Extremely Large Telescope (E-ELT) by looking at the cars nearby.) Image credit: ESO / L.Calcada http://www.eso.org/public/images/elt-fulldome-1_cc/
ESOcast 76: A Polarised View of Stellar Magnetism ESO telescopes are being used to search for the subtle signs of magnetic fields in other stars and even to map out the star spots on their surfaces. This ESOcast looks at how this information — and particularly the polarisation of light — is beginning to reveal how and why so many stars, including our own Sun, are magnetic, and what the implications might be for life on Earth and elsewhere in the Universe. — with Abel Moreira.
ESO has signed an agreement with a consortium of institutes around Europe for the design and construction of METIS, an infrared camera and spectrograph for the European Extremely Large Telescope (E-ELT). The agreement was signed by H. W. (Willem) te Beest, Vice-President Executive Board, Leiden University, on behalf of the consortium, and Tim de Zeeuw, ESO Director General, at a ceremony at the Science Faculty Club of Leiden University in the Netherlands, on 28 September 2015.
Haro 11 appears to shine gently amid clouds of gas and dust, but this placid facade belies the monumental rate of star formation occurring in this starburst” galaxy. By combining data from ESO’s Very Large Telescope and the NASA/ESA Hubble Space Telescope, astronomers have created a new image of this incredibly bright and distant galaxy.
The team of astronomers from Stockholm University, Sweden, and the Geneva Observatory, Switzerland, have identified 200 separate clusters of very young, massive stars. Most of these are less than 10 million years old. Many of the clusters are so bright in infrared light that astronomers suspect that the stars are still emerging from the cloudy cocoons where they were born. The observations have led the astronomers to conclude that Haro 11 is most likely the result of a merger between a galaxy rich in stars and a younger, gas-rich galaxy. Haro 11 is found to produce stars at a frantic rate, converting about 20 solar masses of gas into stars every year.
Haro galaxies, first discovered by the noted astronomer Guillermo Haro in 1956, are defined by unusually intense blue and violet light. Usually this high energy radiation comes from the presence of many newborn stars or an active galactic nucleus. Haro 11 is about 300 million light-years away and is the second closest of such starburst galaxies.
The paper describing this result (“Super star clusters in Haro 11: Properties of a very young starburst and evidence for a near-infrared flux excess”, by A. Adamo et al.) is available here. Credit: ESO/ESA/Hubble and NASA
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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 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. 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 a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.