Press Releases

29 January 2008: Using ESO's Very Large Telescope Interferometer, astronomers have probed the inner parts of the disc of material surrounding a young stellar object, witnessing how it gains its mass before becoming an adult.

27 September 2007: A team of European astronomers has used ESO's Very Large Telescope Interferometer and its razor-sharp eyes to discover a reservoir of dust trapped in a disc that surrounds an elderly star. The discovery provides additional clues about the shaping of planetary nebulae.

27 September 2007: Using ESO's Very Large Telescope Interferometer and its unique ability to see small details, astronomers have uncovered a flat, nearly edge-on disc of silicates in the heart of the magnificent Ant Nebula. The disc seems, however, too 'skinny' to explain how the nebula got its intriguing ant-like shape.

31 May 2007: Using ESO's VLTI on Cerro Paranal and the VLBA facility operated by NRAO, an international team of astronomers has made what is arguably the most detailed study of the environment of a pulsating red giant star. They performed, for the first time, a series of coordinated observations of three separate layers within the star's tenuous outer envelope: the molecular shell, the dust shell, and the maser shell, leading to significant progress in our understanding of the mechanism of how, before dying, evolved stars lose mass and return it to the interstellar medium.

23 February 2007: The ESO Very Large Telescope Interferometer, which allows astronomers to scrutinise objects with a precision equivalent to that of a 130-m telescope, is proving itself an unequalled success every day. One of the latest instruments installed, AMBER, has led to a flurry of scientific results, an anthology of which is being published this week as special features in the research journal Astronomy & Astrophysics.

20 September 2006: Thanks to the unique possibilities offered by ESO's Very Large Telescope Interferometer (VLTI), astronomers have solved a 140-year-old mystery concerning active hot stars. They indeed show that the star Alpha Arae is spinning almost on the verge of breaking and that its disc rotates the same way planets do around the Sun.

24 November 2005: Using the newly installed AMBER instrument on ESO's Very Large Telescope Interferometer, which combines the light from two or three 8.2-m Unit Telescopes thereby amounting to observe with a telescope of 40 to 90 metres in diameter, two international teams of astronomers observed with unprecedented detail the environment of two stars. One is a young, still-forming star and the new results provide useful information on the conditions leading to the creation of planets. The other is on the contrary a star entering the latest stages of its life. The astronomers found, in both cases, evidence for a surrounding disc.

12 January 2005: Last year proved again a wonderful one for astronomy in general and for ESO in particular. Certainly the most important astronomical event for a large public was the unique Transit of Venus: on June 8, 2004, Venus - the Earth's sister planet - passed in front of the Sun. This rare event - the last one occurred in 1882 - attracted the attention of millions of people all over the world.

29 October 2004: Taking advantage of the very high spatial resolution provided by the Very Large Telescope Interferometer, a team of French and Swiss astronomers [1] has measured directly the change in angular diameter of four southern Cepheid variable stars over their pulsation cycle. When combined with spectroscopic radial velocity measurements, this allowed the astronomers to measure very accurately the distances of these stars in a quasi-geometrical way, and to calibrate the zero-point of the Cepheid Period-Luminosity empirical law. These observations constitute a fundamental step towards an independent verification of the extragalactic distance scale by interferometry.

5 April 2004: Another vital step has been accomplished as planned towards full operation of the ESO Very Large Telescope Interferometer (VLTI) at the Paranal Observatory in Chile, one of the world's foremost astronomical facilities. In the night of March 20-21, 2004, a team of astronomers and engineers from France, Italy, Germany and ESO celebrated the successful assembly and completion of the first on-line tests of the latest of the first-generation VLTI instruments, the Astronomical Multiple BEam Recombiner (AMBER). They combined the two beams of light from the southern star Theta Centauri from two test telescopes ("siderostats" with 40-cm aperture) to produce strong and clear interferometric fringes. Equally successful observations were then obtained on the bright star Sirius, and consistently repeated during the following nights.

19 June 2003: Active galactic nuclei (AGN) are one of the most energetic and mysterious phenomena in the universe. In some galaxies indeed, the core generates amounts of energy which surpass those of normal galaxies, such as the Milky Way, by many orders of magnitude. The central engine of these power stations is thought to be a supermassive black hole. Indirect lines of evidence have suggested that these massive black holes are enshrouded in a thick doughnut-shaped structure of gas and dust, which astronomers call a "torus". However, due to the limited sharpness of images that can be obtained with present telescopes in the 10-m range, such a torus has never been imaged to date. Using the new and powerful VLT Interferometer [1] - a mode of the ESO Very Large Telescope that combines light from at least two telescopes to obtain information on very fine scales - a team of European astronomers [2] has succeeded for the first time in resolving structures in the dusty torus of the prototype AGN, the famous galaxy NGC 1068. The structures have a size of roughly 0.03 arcsec, corresponding to about 10 light-years at the distance of the galaxy. This important achievement shows that the VLT Interferometer, using the recently inaugurated MIDI instrument [3], proves an invaluable tool in the study of objects outside our own Galaxy.

22 April 2003: More than 100 exoplanets in orbit around stars other than the Sun have been found so far. But while their orbital periods and distances from their central stars are well known, their true masses cannot be determined with certainty, only lower limits. This fundamental limitation is inherent in the common observational method to discover exoplanets - the measurements of small and regular changes in the central star's velocity, caused by the planet's gravitational pull as it orbits the star. However, in two cases so far, it has been found that the exoplanet's orbit happens to be positioned in such a way that the planet moves in front of the stellar disk, as seen from the Earth. This "transit" event causes a small and temporary dip in the star's brightness, as the planet covers a small part of its surface, which can be observed. The additional knowledge of the spatial orientation of the planetary orbit then permits a direct determination of the planet's true mass. Now, a group of German astronomers [1] have found a third star in which a planet, somewhat larger than Jupiter, but only half as massive, moves in front of the central star every 28.5 hours . The crucial observation of this solar-type star, designated OGLE-TR-3 [2] was made with the high-dispersion UVES spectrograph on the Very Large Telescope (VLT) at the ESO Paranal Observatory (Chile). It is the exoplanet with the shortest period found so far and it is very close to the star, only 3.5 million km away. The hemisphere that faces the star must be extremely hot, about 2000 °C and the planet is obviously losing its atmosphere at high rate.

15 March 2003: Observations with the Very Large Telescope Interferometer (VLTI) at the ESO Paranal Observatory (Chile) have provided the first-ever direct determination of the angular sizes of the disks of the solar-type stars Alpha Centauri A and Alpha Centauri B. As the two largest members of this triple stellar system that also includes the much smaller Proxima Centauri, they are the Sun's nearest neighbours in space at a distance of just over 4 light-years. Together with photometric and asteroseismic observations, this fundamental measurement with the VLTI has lead to a complete characterization of Alpha Centauri A and Alpha Centauri B - they are now the "best known" stars. This has also allowed a unique and very detailed comparison between "real nature" and current stellar theory for solar-type stars. There is clearly very good agreement, indicating that the structure and evolution of stars like our Sun are well understood. The new observations of the nearest stars have therefore contributed to raise the astronomers' confidence in their solar models as well. We can now be more sure about the conditions inside the Sun, our central energy source, and also about the way it will change during the next hundreds of millions of years.

18 December 2002: Following several weeks of around-the-clock work, a team of astronomers and engineers from Germany, the Netherlands, France and ESO [2] has successfully performed the first observations with the MID-Infrared interferometric instrument (MIDI), a new, extremely powerful instrument just installed in the underground laboratory of the VLT Interferometer (VLTI) at the Paranal Observatory (Chile). In the early morning of December 15, 2002, two of the 8.2 m VLT unit telescopes (ANTU and MELIPAL) were pointed towards the southern star Epsilon Carinae and the two light beams were directed via the complex intervening optics system towards MIDI. After a few hours of tuning and optimization, strong and stable interferometric fringes were obtained, indicating that all VLTI components - from telescopes to the new instrument - were working together perfectly. Two more stars were observed before sunrise, further proving the stability of the entire system. The first observations with MIDI mark one more important step towards full and regular operation of the VLT Interferometer [3]. They are a result of five years of determined efforts within a concerted technology project, based on a close collaboration between ESO and several European research institutes (see below). Now opening great research vistas, they also represent several "firsts" in observational astrophysics, together amounting to a real breakthrough in the field of astronomical interferometry.

29 November 2002: At a distance of only 4.2 light-years, Proxima Centauri is the nearest star to the Sun currently known [2]. It is visible as an 11-magnitude object in the southern constellation of Centaurus and is the faintest member of a triple system, together with Alpha Centauri, the brightest (double) star in this constellation. Proxima Centauri is a very-low-mass star, in fact barely massive enough to burn hydrogen to helium in its interior. It is about seven times smaller than the Sun, and the surface temperature is "only" about 3000 degrees, about half of that of our own star. Consequently, it is also much fainter - the intrinsic brightness is only 1/150th of that of our Sun. Low-mass stars are very interesting objects , also because the physical conditions in their interiors have much in common with those of giant planets, like Jupiter in our solar system. A determination of the sizes of the smallest stars has been impossible until now because of their general faintness and lack of adequate instrumentation. However, astronomers have long been keen to move forward in this direction, since such measurements would provide indirect, crucial information about the behaviour of matter under extreme conditions. When the first observations with the VLT Interferometer (VLTI), combining the light from two of the 8.2-m VLT Unit Telescopes (ANTU and MELIPAL), were made one year ago, interferometric measurements were also obtained of Proxima Centauri . They formed part of the VLTI commissioning and the data were soon released to the ESO community, cf. the special website. Now, an international team of astronomers from Switzerland, France and ESO/Chile has successfully analysed these observations by means of newly developed, advanced software. For the first time ever, they obtained a highly accurate measurement of the size of such a small star. Three other small stars were also measured and the results are in excellent agreement with stellar theory, indicating that our present understanding of the structure and composition of very small stars is reasonably correct . More VLTI observations are soon to follow, eventually also of even smaller objects, like Brown Dwarfs.

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.

5 November 2001: It started as a preparatory technical experiment and it soon developed into a spectacular success. Those astronomers and engineers who were present in the control room that night now think of it as the scientific dawn of the Very Large Telescope Interferometer (VLTI). On October 29, 2001, ANTU and MELIPAL, two of the four VLT 8.2-metre Unit Telescopes at the ESO Paranal Observatory, were linked for the first time. Light from the southern star Achernar (Alpha Eridani) was captured by the two telescopes and sent to a common focus in the observatory's Interferometric Laboratory.

6 April 2001: Representatives from Europe, Japan, and North America met in Tokyo today and signed a Resolution affirming their mutual intent to construct and operate a giant radio telescope in co-operation with the Republic of Chile, where the telescope will be located.

18 March 2001: Following the "First Light" for the fourth of the 8.2-metre telescopes of the VLT Observatory on Paranal in September 2000, ESO scientists and engineers have just successfully accomplished the next major step of this large project.

13 November 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.