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New Orion vista reveals high-speed antics of young stars
Posted: 10 February 2010

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Captured by ESO's new Visible and Infrared Survey Telescope for Astronomy, VISTA, the Orion Nebula is revealed in greater detail than ever before.

This wide-field view of the Orion Nebula (Messier 42), lying about 1350 light-years from Earth, was taken with the VISTA infrared survey telescope at ESO’s Paranal Observatory in Chile. The image covers a region of sky about one degree by 1.5 degrees. Image: ESO/J. Emerson/VISTA. Acknowledgment: Cambridge Astronomical Survey Unit.

VISTA is the latest – and largest – addition to ESO's Paranal Observatory. With a 4.1 metre mirror, wide field of view and sensitive detectors, VISTA can penetrate the dusty regions of youthful star formation that are usually invisible. While spectacular even through a modest telescope, VISTA's detectors are sensitive to wavelengths about twice as long as can be seen by the human eye, meaning it can peer through the dust that the human eye cannot. Its huge field of view also allows the whole nebula and its surroundings to be imaged in a single picture.

On the upper-left, the central region of VISTA’s view of the Orion Nebula is shown, centred on the four dazzling stars of the Trapezium. In the lower-right the part of the nebula to the north of the centre is shown where there are many young stars embedded in the dust clouds. Outflows, jets and other interactions from young stars are apparent as red blobs. On the upper-right, a region to the west of centre is shown where fierce ultraviolet light from the Trapezium is sculpting the gas clouds into curious wavy shapes. At the lower-left a region south of the centre is shown. Each extract covers a region of sky about nine arcminutes across. Image: ESO/J. Emerson/VISTA. Acknowledgment: Cambridge Astronomical Survey Unit.

The new VISTA image of Orion reveals many familiar sights, including the four young, bright stars that make up the Trapezium in the heart of the region that are pumping out intense ultraviolet radiation, which in turn clears the surrounding region and causes the gas glow. Many other young stars are revealed by VISTA in this central region that cannot be seen in visible light, including those with a very active temperament.

Comparison of the Orion Nebula in visible light (left) and with VISTA (right). Image: ESO/J. Emerson/VISTA & R. Gendler. Acknowledgment: Cambridge Astronomical Survey Unit.

Just above the centre of the image are strange red features that are completely invisible except at infrared wavelengths. These features are attributed to very young stars that are still growing and ejecting streams of gas at speeds of some 700,000 kilometres per hour. The red features mark the locations where the gas streams collide with the surrounding gas, causing emission from excited molecules and atoms in the gas. Fainter red features are also visible below the Orion Nebula in this image, showing that stars are forming here too, but with much less vigour.

VISTA is just embarking on a its sky survey, and will image wide areas of the sky quickly and deeply at near-infrared wavelengths.