Pressemeddelelser

31. oktober 2002: Visit http://www.cern.ch/sci-tech on 7 - 8 November to find out what modern Europeans can't live without. Seven of Europe's leading Research Organizations [1] are presenting three live Webcasts from CERN in a joint outreach programme for the European Science and Technology Week . The aim of Sci-Tech... couldn't be without it! is to show how today's society couldn't be without cutting-edge scientific research.

30. oktober 2002: A faint star in the southern Milky Way, designated HE 0107-5240 , has been found to consist virtually only of hydrogen and helium . It has the lowest abundance of heavier elements ever observed , only 1/200,000 of that of the Sun - 20 times less than the previous record-holding star. This is the result of a major ongoing research project by an international team of astronomers [2]. It is based on a decade-long survey of the southern sky, with detailed follow-up observations by means of the powerful UV-Visual Echelle Spectrograph (UVES) on the 8.2-m VLT KUEYEN telescope at the ESO Paranal Observatory in Chile. This significant discovery now opens a new window towards the early times when the Milky Way galaxy was young, possibly still in the stage of formation. It proves that, contrary to most current theories, comparatively light stars like HE 0107-5240 (with 80% of the mass of the Sun) may form in environments (nearly) devoid of heavier elements. Since some years, astronomers have been desperately searching for stars of the very first stellar generation in the Milky Way, consisting only of hydrogen and helium from the Big Bang. None have been detected so far and doubts have arisen that they exist at all. The present discovery provides new hope that it will ultimately be possible to find such stellar relics from the young Universe and thereby to study "unpolluted" Big Bang material.

23. oktober 2002: On October 21, 2002, the Minister of Foreign Affairs of the Republic of Chile, Mrs. María Soledad Alvear and the ESO Director General, Dr. Catherine Cesarsky , signed an Agreement that authorizes ESO to establish a new center for astronomical observation in Chile .

16. oktober 2002: An international team of astronomers [2], lead by researchers at the Max-Planck Institute for Extraterrestrial Physics (MPE) , has directly observed an otherwise normal star orbiting the supermassive black hole at the center of the Milky Way Galaxy. Ten years of painstaking measurements have been crowned by a series of unique images obtained by the Adaptive Optics (AO) NAOS-CONICA (NACO) instrument [3] on the 8.2-m VLT YEPUN telescope at the ESO Paranal Observatory. It turns out that earlier this year the star approached the central Black Hole to within 17 light-hours - only three times the distance between the Sun and planet Pluto - while travelling at no less than 5000 km/sec. Previous measurements of the velocities of stars near the center of the Milky Way and variable X-ray emission from this area have provided the strongest evidence so far of the existence of a central Black Hole in our home galaxy and, implicitly, that the dark mass concentrations seen in many nuclei of other galaxies probably are also supermassive black holes. However, it has not yet been possible to exclude several alternative configurations. In a break-through paper appearing in the research journal Nature on October 17th, 2002, the present team reports their exciting results, including high-resolution images that allow tracing two-thirds of the orbit of a star designated "S2" . It is currently the closest observable star to the compact radio source and massive black hole candidate "SgrA*" ("Sagittarius A") at the very center of the Milky Way. The orbital period is just over 15 years. The new measurements exclude with high confidence that the central dark mass consists of a cluster of unusual stars or elementary particles, and leave little doubt of the presence of a supermassive black hole at the centre of the galaxy in which we live.

26. september 2002: During the nights of September 15/16 and 16/17, 2002, preliminary tests were successfully carried out during which the light beams from all four VLT 8.2-m Unit Telescopes (UTs) at the ESO Paranal Observatory were successively combined, two by two, to produce interferometric fringes . This marks a next important step towards the full implementation of the VLT Interferometer (VLTI) that will ultimately provide European astronomers with unequalled opportunities for exciting front-line research projects. It is no simple matter to ensure that the quartet of ANTU, KUEYEN, MELIPAL and YEPUN , each a massive giant with a suite of computer-controlled active mirrors, can work together by sending beams of light towards a common focal point via a complex system of compensating optics. Yet, in the span of only two nights, the four VLT telescopes were successfully "paired" to do exactly this, yielding a first tantalizing glimpse of the future possibilities with this new science machine. While there is still a long way ahead to the routine production of extremely sharp, interferometric images, the present test observations have allowed to demonstrate directly the 2D-resolution capacity of the VLTI by means of multiple measurements of a distant star. Much valuable experience was gained during those two nights and the ESO engineers and scientists are optimistic that the extensive test observations with the numerous components of the VLTI will continue to progress rapidly. Five intense, technical test periods are scheduled during the next six months; some of these with the Mid-Infrared interferometric instrument for the VLTI (MIDI) which will soon be installed at Paranal. Later in 2003, the first of the four moveable VLTI 1.8-m Auxiliary Telescopes (ATs) will be put in place on the top of the mountain; together they will permit regular interferometric observations, also without having to use the large UTs.

28. august 2002: A rare celestial phenomenon involving the distant planet Pluto has occurred twice within the past month. Seen from the Earth, this planet moved in front of two different stars on July 20 and August 21, respectively, providing observers at various observatories in South America and in the Pacific area with a long awaited and most welcome opportunity to learn more about the tenuous atmosphere of that cold planet. On the first date, a series of very sharp images of a small sky field with Pluto and the star was obtained with the NAOS-CONICA (NACO) adaptive optics (AO) camera mounted on the ESO VLT 8.2-m YEPUN telescope at the Paranal Observatory.

23. august 2002: Do very massive stars form in metal-rich regions of the Universe and in the nuclei of galaxies ? Or does "heavy element poisoning" stop stellar growth at an early stage, before young stars reach the "heavyweight class"? What may at the first glance appear as a question for specialists actually has profound implications for our understanding of the evolution of galaxies, those systems of billions of stars - the main building blocks of the Universe. With an enormous output of electromagnetic radiation and energetic elementary particles, massive stars exert a decisive influence on the surrounding (interstellar) gas and dust clouds . They also eject large amounts of processed elements, thereby participating in the gradual build-up of the many elements we see today. Thus the presence or absence of such stars at the centres of galaxies can significantly change the overall development of those regions and hence, presumably, that of the entire galaxy. A team of European astronomers [2] has now directly observed the presence of so-called Wolf-Rayet stars (born with masses of 60 - 90 times that of the Sun or more) within metal-rich regions in some galaxies in the Virgo cluster, some 50 million light-years away. This is the first unambiguous detection of such massive stellar objects in metal-rich regions.

9. august 2002: Thirty-three years after the first manned landing on the Moon, the ESO Very Large Telescope (VLT) has obtained what may be the sharpest image of the lunar surface ever recorded from the ground . It was made with the NAOS-CONICA (NACO) adaptive optics camera mounted on the ESO VLT 8.2-m YEPUN telescope at the Paranal Observatory.

7. august 2002: A series of wide-field images centred on the nearby spiral galaxy NGC 300 , obtained with the Wide-Field Imager (WFI) on the MPG/ESO 2.2-m telescope at the La Silla Observatory, have been combined into a magnificent colour photo. These images have been used by different groups of astronomers for various kinds of scientific investigations, ranging from individual stars and nebulae in NGC 300, to distant galaxies and other objects in the background. This material provides an interesting demonstration of the multiple use of astronomical data, now facilitated by the establishment of extensively documented data archives, like the ESO Science Data Archive that now is growing rapidly and already contains over 15 Terabyte. Based on the concept of Astronomical Virtual Observatories (AVOs) , the use of archival data sets is on the rise and provides a large number of scientists with excellent opportunities for front-line investigations without having to wait for precious observing time. In addition to presenting a magnificent astronomical photo, the present account also illustrates this important new tool of the modern science of astronomy and astrophysics.

1. august 2002: A team of European astronomers [2] have observed eight Brown Dwarfs, i.e., small and faint objects also known as "failed stars", with the TIMMI2 infrared sensitive instrument at the ESO 3.6-m telescope on La Silla. From two of these, mid-infrared radiation is detected - for the first time ever from such objects with a ground-based telescope . While the younger Brown Dwarf, aged a few million years, is found to be surrounded by a dusty disk, no warm dust is present around the older ones. The new observations support the following formation hypothesis for Brown Dwarfs: they are born in the same way as "real" stars, by contraction in interstellar clouds of gas and dust . During the later stages of this process, the infalling material is transferred onto the star via a gas and dust disk . This disk - in which planets may possibly form - then disperses with time.

8. juli 2002: The first observations of stellar spectra have just been performed with the new GIRAFFE multi-object spectrograph on the ESO Very Large Telescope (VLT) at the Paranal Observatory in Chile. This milestone event was achieved in the early morning of July 3, 2002. It signifies another important step towards the full implementation of the extremely powerful Fibre Large Array Multi-Element Spectrograph (FLAMES), one of the main instruments for the ESO VLT. This project is co-ordinated by ESO and incorporates many complex components that have been constructed at various research institutions in Europe and Australia. The GIRAFFE spectrograph provides unique possibilities for detailed observations of the properties of individual stars located in our Milky Way galaxy ( PR 16b/02 ) as well as in other galaxies of the Local Group.

8. juli 2002: A significant milestone for British and European science occurred today (July 8, 2002) when the Council of the European Southern Observatory (ESO) met in London. At this historical meeting, the United Kingdom was formally welcomed into ESO by the nine other member states.

26. juni 2002: Combining data from the NASA/ESA Hubble Space Telescope (HST) and the ESO Very Large Telescope (VLT) , a group of European and American astronomers [2] have made an unexpected, major discovery. They have identified a huge number of "young" stellar clusters , only a few billion years old [3], inside an "old" elliptical galaxy (NGC 4365), probably aged some 12 billion years. For the first time, it has been possible to identify several distinct periods of star-formation in a galaxy as old as this one. Elliptical galaxies like NGC 4365 have until now been considered to have undergone one early star-forming period and thereafter to be devoid of any star formation. However, the combination of the best and largest telescopes in space and on the ground has now clearly shown that there is more than meets the eye. This important new information will help to understand the early history of galaxies and the general theory of star formation in the Universe.

7. juni 2002: The largest emission nebula in the sky, the Tarantula Nebula (also known as NGC 2070 or 30 Doradus) is located in the Large Magellanic Cloud (LMC), one of the satellite galaxies to our own Milky Way system. Seen far down in the southern sky at a distance of about 170,000 light-years, this beautiful nebula measures more than 1000 light-years across and extends over more than one third of a degree, almost, but not quite the size of the full moon. It received its descriptive name because of the unusual shape.

15. maj 2002: About 30 years ago, astronomers realised that the Sun resonates like a giant musical instrument with well-defined periods (frequencies). It forms a sort of large, spherical organ pipe. The energy that excites these sound waves comes from the turbulent region just below the Sun's visible surface.
Observations of the solar sound waves (known as "helioseismology") have resulted in enormous progress in the exploration of the interior of the Sun, otherwise hidden from view. As is the case on Earth, seismic techniques can be applied and the detailed interpretation of the observed oscillation periods has provided quite accurate information about the structure and motions inside the Sun, our central star. It has now also become possible to apply this technique to some solar-type stars. The first observations concerned the northern star eta Bootis. Last year, extensive and much more accurate observations with the 1.2-m Swiss telescope at the ESO La Silla Observatory proved that Alpha Centauri , a solar "twin", behaves very much like the Sun, and that some of the periods are quite similar to those in the Sun. These new observational data were of a superb quality, and that study marked a true break-through in the new research field of "asteroseismology" (seismology of the stars) for solar-type stars. But what about other types of stars, for instance those that are much larger than the Sun?

7. maj 2002: Using the ESO 3.5-m New Technology Telescope and the Very Large Telescope (VLT) , a team of astronomers [1] have discovered a dusty and opaque disk surrounding a young solar-type star in the outskirts of a dark cloud in the Milky Way. It was found by chance during an unrelated research programme and provides a striking portrait of what our Solar System must have looked like when it was in its early infancy. Because of its striking appearance, the astronomers have nicknamed it the "Flying Saucer." The new object appears to be a perfect example of a very young star with a disk in which planets are forming or will soon form, and located far away from the usual perils of an active star-forming environment . Most other young stars, especially those that are born in dense regions, run a serious risk of having their natal dusty disks destroyed by the blazing radiation of their more massive and hotter siblings in these clusters. The star at the centre of the "Flying Saucer", seems destined to live a long and quiet life at the centre of a planetary system, very much like our own Sun. This contributes to making it a most interesting object for further studies with the VLT and other telescopes. The mass of the observed disk of gas and dust is at least twice that of the planet Jupiter and its radius measures about 45 billion km, or 5 times the size of the orbit of Neptune.

2. maj 2002: This is the full title of an innovative educational project, launched today by the European Southern Observatory (ESO) and the European Association for Astronomy Education (EAAE). It welcomes all students in Europe's schools to an exciting web-based programme with a competition. It takes place within the context of the EC-sponsored European Week of Science and Technology (EWST) - 2002. This unique project revolves around a web-based competition and is centred on astronomy. It is specifically conceived to stimulate the interest of young people in various aspects of this well-known field of science, but will also be of interest to the broad public.

9. april 2002: Using the ESO Very Large Telescope (VLT) , a team of astronomers from The Netherlands, Germany, France and the USA [1] have discovered the most distant group of galaxies ever seen , about 13.5 billion light-years away. It has taken the light now recorded by the VLT about nine-tenths of the age of the Universe to cover the huge distance. We therefore observe those galaxies as they were at a time when the Universe was only about 10% of its present age. The astronomers conclude that this group of early galaxies will develop into a rich cluster of galaxies, such as those seen in the nearby Universe. The newly discovered structure provides the best opportunity so far for studying when and how galaxies began to form clusters after the initial Big Bang , one of the greatest puzzles in modern cosmology.

15. marts 2002: Observations with ESO's Very Large Telescope (VLT) in Chile and the Italian Telescopio Nazionale Galileo (TNG) on the Canary Islands during the past two years have enabled an international group of astronomers [1] to unravel the true nature of an exceptional binary stellar system. This system, designated RX J0806.3+1527 , was first discovered as an X-ray source of variable brightness - once every five minutes, it "switches off" for a short moment. The new observations have shown beyond doubt that this period reflects the orbital motion of two "white dwarf" stars that revolve around each other at a distance of only 80,000 km . Each of the stars is about as large as the Earth and this is the shortest orbital period known for any binary stellar system. The VLT spectrum displays lines of ionized helium, indicating that the presence of an exceedingly hot area on one of the stars - a "hot spot" with a temperature of approx. 250,000 degrees. The system is currently in a rarely seen, transitory evolutionary state.

13. marts 2002: Seven of Europe's leading Research Organizations [1] launch joint outreach programme for the European Science and Technology Week at the Technopolis Museum in Brussels on 22 March. Their aim is to show Europeans how today's society couldn't be without fundamental research .