Communiqués de presse

13 mars 2001: Important scientific advances often happen when complementary investigational techniques are brought together. In the present case, X-ray and optical/infrared observations with some of the world's foremost telescopes have provided the crucial information needed to solve a 40-year old cosmological riddle.

8 mars 2001: The nearby galaxy Centaurus A harbours a supermassive black hole at its centre. Using the ISAAC instrument at the ESO Very Large Telescope (VLT), an international team of astronomers [1] has peered right through the spectacular dust lane of the peculiar galaxy Centaurus A, located approximately 11 million light-years away. They were able to probe the thin disk of gas that surrounds the very center of this galaxy. The new measurements show that the compact nucleus in the middle weighs more than 200 million solar masses! This is too much just to be due to normal stars. The astronomers thus conclude the existence of a supermassive black hole lurking at the centre of Centaurus A.

6 mars 2001: ESO has released a new image of the famous comet Hale-Bopp, where the large nucleus of ice and dust is still seen glowing. This is very unusual since the comet is currently in a very cold place, between the orbits of Saturn and Uranus, almost 2000 million kilometres away from the Sun.

2 mars 2001: Globular clusters are very massive assemblies of stars. More than 100 are known in the Milky Way galaxy and most of them harbour several million stars. They are very dense - at their centers, the typical distance between individual stars is comparable to the size of the Solar System, or 100 to 1000 times closer than the corresponding distances between stars in the solar neighborhood. Globular clusters are among the oldest objects known , with estimated ages of 11 to 15 billion years [1]. All stars in a globular cluster were formed at nearly the same moment, and from the same parent cloud of gas and dust. The original chemical composition of all stars is therefore the same. But now, an international group of astronomers [2], working with the UVES Spectrograph at the ESO Very Large Telescope (VLT), have obtained some unexpected results during a detailed analysis of dwarf stars in some globular clusters . Such stars have about the same mass as our Sun and like it, they evolve very slowly. Thus they still ought to have about the same abundances of most chemical elements.

7 février 2001: Most astronomers would agree that the age of the Universe - the time elapsed since the "Big Bang" - is one of the "holy grails of cosmology". Despite great efforts during recent years, the various estimates of this basic number have resulted in rather diverse values. When derived from current cosmological models, it depends on a number of theoretical assumptions that are not very well constrained by the incomplete available observational data. At present, a value in the range of 10-16 billion years [1] is considered most likely. But now, an international team of astronomers [2] has used the powerful ESO Very Large Telescope (VLT) and its very efficient spectrograph UVES to perform a unique measurement that paves the way for a new and more accurate determination of the age of the Universe. 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. It is the first measurement ever of uranium outside the Solar System.

26 janvier 2001: Last year saw very good progress at ESO's Paranal Observatory, the site of the Very Large Telescope (VLT). The third and fourth 8.2-metre Unit Telescopes, MELIPAL and YEPUN had "First Light," while the first two, ANTU and KUEYEN, were busy collecting first-class data for hundreds of astronomers. Meanwhile, work continued towards the next phase of the VLT project, the combination of the telescopes into the VLT Interferometer. The test instrument, VINCI is now being installed in the VLTI Laboratory at the centre of the observing platform on the top of Paranal.

17 janvier 2001: Orion the Hunter is perhaps the best known constellation in the sky, well placed in the evening at this time of the year for observers in both the northern and southern hemispheres, and instantly recognisable. And for astronomers, Orion is surely one of the most important constellations, as it contains one of the nearest and most active stellar nurseries in the Milky Way, the galaxy in which we live.

11 janvier 2001: This Video Clip is issued on the web in conjunction with the release of an 18-min documentary video from the Science Festival of the "Physics On Stage" programme. This unique event took place during November 6-11, 2000, on the CERN premises at the French-Swiss border near Geneva, and formed part of the European Science and Technology Week 2000, an initiative by the European Commission to raise the public awareness of science in Europe.

10 janvier 2001: How do stars like our Sun come into being? Which fundamental processes are responsible for transforming a dark and diffuse interstellar cloud of gas and dust into a much denser, shining object? Astronomers have just taken an important step towards answering this fundamental question. Based on the most detailed study ever made of the internal structure of a small interstellar cloud, three scientists from ESO and the USA [1] have found that it is apparently on the verge of becoming unstable - and thus in the stage immediately preceding a dramatic collapse into a dense and hot, low-mass star.

4 janvier 2001: At the beginning of the new millennium, ESO and its staff are facing the future with confidence. The four 8.2-metre Unit Telescopes of the Very Large Telescope (VLT) are in great shape and the VLT Interferometer (VLTI) will soon have "first fringes". The intercontinental ALMA project is progressing well and concepts for extremely large optical/infrared telescopes are being studied.

22 décembre 2000: Merry Christmas and a Happy New Year!

20 décembre 2000: Some years ago, the Paranal mountain was still a remote and inhospitable site, some 12 km from the Pacific Coast in the dry Atacama desert in northern Chile. Few aircraft passengers flying along that coast would notice anything particular about this peak, except perhaps that it was one of the tallest in the steep coastal mountain range. Already in the early 1960's, pioneer astronomers crossed this desolate region in search of suitable sites for future observatories. One of them, Jürgen Stock, did notice the Paranal peak as a possible candidate. However, without any water in this extremely dry area, how could any people, even hardy scientists, ever live up there? He then went on to discover La Silla, where ESO decided to build its first observatory in 1964.

20 décembre 2000: A fundamental prediction of the Big Bang theory has finally been verified. For the first time, an actual measurement has been made of the temperature of the cosmic microwave background radiation, at a time when the Universe was only about 2.5 billion years old. This fundamental and very difficult observation was achieved by a team of astronomers from India, France and ESO [1]. They obtained a detailed spectrum of a quasar in the distant Universe, using the UV-Visual Echelle Spectrograph (UVES) instrument at the ESO 8.2-m VLT KUEYEN telescope at the Paranal Observatory.

13 décembre 2000: Due to a happy coincidence, the ESO/ST-ECF Science Archive Facility is celebrating three different milestones at the same time: 1) its 10th anniversary since the establishment in 1991, 2) the 10,000th request for data, and 3) the signing-up of active user number 2000. This Archive contains over 8 Terabytes (1 Terabyte = 1 million million bytes) of valuable observational data from the NASA/ESA Hubble Space Telescope (HST), the ESO Very Large Telescope (VLT) and other ESO telescopes. Its success paves the way for the establishment of "Virtual Observatories" from which first-class data can be obtained by astronomers all over the world. This greatly enhances the opportunities for more (young) scientists to participate in front-line research.

8 décembre 2000: The most massive spiral galaxy known so far in the Universe has been discovered by a team of astronomers from Garching, Padova, Leiden, ESO and London [1]. They base their conclusion on recent observations with ISAAC, an infrared-sensitive, multi-mode instrument on ESO's Very Large Telescope at the Paranal Observatory. This galaxy has been designated ISOHDFS 27 and is located at a distance of approx. 6 billion light-years (the redshift is 0.58). Its measured mass is more than 1000 billion times that of the Sun [2]. It is thus about four times more massive than our own galaxy, the Milky Way, and twice as heavy as the heaviest spiral galaxy known so far.

1 décembre 2000: An international team of astronomers [1] has succeeded in mapping the "dark" (invisible) matter in the Universe, as seen in 50 different directions from the Earth. They find that, within the uncertainty, it is unlikely that mass alone would stop the current expansion of the Universe. This fundamental result is based on the powerful, but challenging method of "cosmic shear". It depends on very accurate measurements of the apparent, weak distortion and preferential orientation of images of distant galaxies. This effect is caused by deflection of the light from those galaxies by the large mass concentrations in the Universe it encounters on its way to us. The larger these masses are, the larger are the apparent image distortions and the more pronounced are the alignments of neigbouring galaxy images. The new analysis was made possible by means of unique observational data, obtained under excellent conditions with the the ESO 8.2-m VLT ANTU telescope and the multi-mode FORS1 instrument at the Paranal Observatory.

22 novembre 2000: The Particle Physics and Astronomy Research Council (PPARC), the UK's strategic science investment agency, today announced that the government of the United Kingdom is making funds available that provide a baseline for this country to join the European Southern Observatory (ESO).

13 novembre 2000: A few months from now, light from celestial objects will be directed for the first time towards ESO's Very Large Telescope Interferometer (VLTI) at the Paranal Observatory (Chile). During this "First Light" event and the subsequent test phase, the light will be recorded with a special test instrument, VINCI (VLT INterferometer Commissioning Instrument). The main components of this high-tech instrument are aptly named MONA (a system that combines the light beams from several telescopes by means of optical fibers) and LISA (the infrared camera). VINCI was designed and constructed within a fruitful collaboration between ESO and several research institutes and industrial companies in France and Germany. It is now being assembled at the ESO Headquarters in Garching (Germany) and will soon be ready for installation at the telescope on Paranal. With the VLTI and VINCI, Europe's astronomers are now entering the first, crucial phase of an exciting scientific and technology venture that will ultimately put the world's most powerful optical/IR interferometric facility in their hands.

27 octobre 2000: A remarkable, wide-field infrared image allows to see in unprecedented detail the inner regions of RCW 108, a large complex of stars and nebulae in the southern Milky Way. It is one of the widest, "deepest" and most spectacular infrared astronomical images ever obtained of a starforming region. It is based on approx. 600 individual exposures with the SOFI multi-mode instrument on the ESO 3.58-metre New Technology Telescope (NTT) at the ESO La Silla Observatory (Chile).

26 octobre 2000: Four new moons have been discovered orbiting Saturn, raising the number to twenty-two. This means that Saturn is now the planet in the Solar System with most known satellites. The previous record holder, Uranus, has twenty-one known satellites. Two of the new objects were first seen with the Wide-Field Imager (WFI) camera at the ESO La Silla Observatory (Chile). They have diameters of 10 to 50 km, and calculations have shown that they are almost certainly small satellites (moons) that accompany Saturn on irregular orbits.