Pressemitteilungen

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eso0414 — Pressemitteilung Wissenschaft
Closer to the Monster
5. Mai 2004: Fulfilling an old dream of astronomers, observations with the Very Large Telescope Interferometer (VLTI) at the ESO Paranal Observatory (Chile) have now made it possible to obtain a clear picture of the immediate surroundings of the black hole at the centre of an active galaxy. The new results concern the spiral galaxy NGC 1068, located at a distance of about 50 million light-years. They show a configuration of comparatively warm dust (about 50°C) measuring 11 light-years across and 7 light-years thick, with an inner, hotter zone (500°C), about 2 light-years wide. These imaging and spectral observations confirm the current theory that black holes at the centres of active galaxies are enshrouded in a thick doughnut-shaped structure of gas and dust called a "torus." For this trailblazing study, the first of its kind of an extragalactic object by means of long-baseline infrared interferometry, an international team of astronomers [2] used the new MIDI instrument in the VLTI Laboratory. It was designed and constructed in a collaboration between German, Dutch and French research institutes [3]. Combining the light from two 8.2-m VLT Unit Telescopes during two observing runs in June and November 2003, respectively, a maximum resolution of 0.013 arcsec was achieved, corresponding to about 3 light-years at the distance of NGC 1068. Infrared spectra of the central region of this galaxy were obtained that indicate that the heated dust is probably of alumino-silicate composition. The new results are published in a research paper appearing in the May 6, 2004, issue of the international research journal Nature.
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eso0412 — Pressemitteilung Wissenschaft
A "Dragon" on the Surface of Titan
14. April 2004: New images of unsurpassed clarity have been obtained with the ESO Very Large Telescope (VLT) of formations on the surface of Titan, the largest moon in the Saturnian system. They were made by an international research team [1] during recent commissioning observations with the "Simultaneous Differential Imager (SDI)", a novel optical device, just installed at the NACO Adaptive Optics instrument [2]. With the high-contrast SDI camera, it is possible to obtain extremely sharp images in three colours simultaneously. Although mainly conceived for exoplanet imaging, this device is also very useful for observations of objects with thick atmospheres in the solar system like Titan. Peering at the same time through a narrow, unobscured near-infrared spectral window in the dense methane atmosphere and an adjacent non-transparent waveband, images were obtained that are virtually uncontaminated by atmospheric components. They map the reflectivity of a large number of surface features in unprecedented detail. The images show a number of surface regions with very different reflectivity. Of particular interest are several large "dark" areas of uniformly low reflectivity. One possible interpretation is that they represent huge surface reservoirs of liquid hydrocarbons. Whatever the case, these new observations will be most useful for the planning of the delivery of the Huygens probe - now approaching the Saturn system on the NASA/ESA Cassini spacecraft and scheduled for descent to Titan's surface in early 2005.
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eso0404 — Organisatorische Pressemitteilung
Announcing the VT-2004 Public Education Programme
16. Februar 2004: On June 8, 2004, Venus - the Earth's sister planet - will pass in front of the Sun. This event, a 'transit', is extremely rare - the last one occurred in 1882, 122 years ago. Easily observable in Europe, Asia, Africa and Australia, it is likely to attract the attention of millions of people on these continents and, indeed, all over the world. On this important occasion, the European Southern Observatory (ESO) has joined forces with the European Association for Astronomy Education (EAAE), the Institut de Mécanique Céleste et de Calcul des Éphémérides (IMCCE) and the Observatoire de Paris in France, as well as the Astronomical Institute of the Academy of Sciences of the Czech Republic to establish the Venus Transit 2004 (VT-2004) public education programme. It is supported by the European Commission in the framework of the European Science and Technology Week and takes advantage of this extraordinary celestial event to expose the public - in a well-considered, interactive and exciting way - to a number of fundamental issues at the crucial interface between society and basic science. VT-2004 has several components, including an instructive and comprehensive website (www.vt-2004.org). It is directed towards the wide public in general and the media, school students and their teachers, as well as amateur astronomers in particular. It invites all interested persons to participate actively in the intercontinental VT-2004 Observing Campaign (that reenacts historical Venus Transit observations) and the VT-2004 Video Contest. During the VT-2004 Final Event in November, the winners of the Video Contest will be chosen by an international jury. This meeting will also serve to discuss the project and its impact.
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eso0339 — Pressemitteilung Wissenschaft
The Colour of the Young Universe
19. Dezember 2003: An international team of astronomers [1] has determined the colour of the Universe when it was very young. While the Universe is now kind of beige, it was much bluer in the distant past , at a time when it was only 2,500 million years old. This is the outcome of an extensive and thorough analysis of more than 300 galaxies seen within a small southern sky area, the so-called Hubble Deep Field South. The main goal of this advanced study was to understand how the stellar content of the Universe was assembled and has changed over time. Dutch astronomer Marijn Franx , a team member from the Leiden Observatory (The Netherlands), explains: "The blue colour of the early Universe is caused by the predominantly blue light from young stars in the galaxies. The redder colour of the Universe today is caused by the relatively larger number of older, redder stars." The team leader, Gregory Rudnick from the Max-Planck Institut für Astrophysics (Garching, Germany) adds: "Since the total amount of light in the Universe in the past was about the same as today and a young blue star emits much more light than an old red star, there must have been significantly fewer stars in the young Universe than there is now. Our new findings imply that the majority of stars in the Universe were formed comparatively late, not so long before our Sun was born, at a moment when the Universe was around 7,000 million years old." These new results are based on unique data collected during more than 100 hours of observations with the ISAAC multi-mode instrument at ESO's Very Large Telescope (VLT), as part of a major research project, the Faint InfraRed Extragalactic Survey (FIRES) . The distances to the galaxies were estimated from their brightness in different optical near-infrared wavelength bands.
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