The European Southern Observatory ESO Images
The European Southern Observatory is an intergovernmental, European organisation for astronomical research. It operates the La Silla Paranal Observatory at several sites in the Atacama desert region of Chile. The first site is at La Silla, a 2400 m high mountain 600 km north of Santiago de Chile.  It is equipped with several optical telescopes with mirror diameters of up to 3.6 metres. The 3.5-m New Technology Telescope (NTT) was the first in the world to have a computer-controlled main mirror.

Whilst La Silla remains one of the scientifically most productive observing sites in the world, the 2600 m high Paranal site with the Very Large Telescope array (VLT) is the flagship facility of European astronomy.  Paranal is situated about 130 km south of Antofagasta in Chile, 12 km inland from the Pacific Coast in what is probably the driest area in the world.  Scientific operations began in 1999 and have resulted in many highly successful research programmes.  The VLT is a most unusual telescope, based on the latest technology.  It is not just one, but an array of four telescopes, each with a main mirror of 8.2-m diameter.  With one such telescope, images of celestial objects as faint as magnitude 30 have been obtained in a one-hour exposure.  This corresponds to seeing objects that are four billion times fainter than what can be seen with the naked eye.  Here is a selection of images from the facility.

 

The Butterfly Nebula - NGC 6302

This image of the famous southern Planetary Nebula, was taken on 22nd May, 1998, with 10 minute exposures and an image quality better than 0.6 arcseconds.  Towards the end of their life, some massive stars expand to giant dimensions. They shed most of the hydrogen in their outer layers as a strong "stellar wind", before they contract towards a final compact stage as "white dwarfs".   After this ejection process, the star remains thousands of times brighter and also much hotter than the Sun during a few thousand years.  Its strong ultraviolet radiation has the effect of ionizing the previously ejected gas, which then shines before it disperses into interstellar space.  The resulting nebulae (traditionally referred to as Planetary Nebulae because of their resemblance to a planet in a small telescope) often exhibit very complex shapes.

The Butterfly Nebula belongs to the class of bipolar nebulae, as this picture clearly illustrates.  A dark, dusty and disc-like structure - seen edge-on in this image - obscures the central star from our view.  However, its strong radiation escapes perpendicular to the disk and heats and illuminates the material deposited there by the stellar wind.  The origin of the dark disk may be due to the central star being a member of a double star system.  This has been shown to be the case in some other bipolar nebulae in which, contrary to the Butterfly Nebula, there is a direct view towards the star.  There is a large (1.5Mb) Image here.

NGC 7424

The face-on, barred spiral galaxy NGC7424 (site of the rare Type IIb Supernova, SN2001ig).  In this supernova there are two ultra-luminous X-ray sources.  Full Resolution Image (5.6Mb)

NGC 1365

NGC 1365 is one of the most prominent "barred" galaxies in the sky.  It is a supergiant galaxy with a diameter of about 200,000 light years, and located in the direction of the southern constellation Fornax (The Furnace). It is a major member of the Fornax Cluster of Galaxies . The distance is about 60 million light-years and the recession velocity has been measured as 1632 km/sec.  A massive straight bar runs through this galaxy and contains the nucleus at the centre. It consists mostly of older stars that give a reddish colour to the bar.  The gravitational perturbation from the bar causes interstellar gas and dust clouds to form a pair of spiral arms that extend from the ends of the bar. Young luminous hot stars, born out of the interstellar clouds, give these arms a prominent appearance and a blue colour.  The bar and spiral pattern rotates clockwise, as seen from us. One full turn takes about 350 million years.  Full Resolution Image (4.5Mb)

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