N44 in the Large Magellanic Cloud Detail
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N44 in the Large Magellanic Cloud (Detail)

May 19, 2005
The Wide Field Imager (WFI) , a 67-million pixel digital camera at the MPG/ESO 2.2-m telescope at the La Silla Observatory continues to produce remarkable images for astronomical research. At the same time, many of these are of great aesthetic value and provide impressive views into sky regions with unsual objects.

Earlier this year, the WFI recorded a number of fields in the direction of the Large Magellanic Cloud (LMC) , a satellite galaxy to our own Milky Way Galaxy, deep down in the southern sky. It is located at a distance of about 170,000 light-years and contains many nebulae and stellar clusters.

Two colour composite photos of "H II regions" in the LMC are shown here, centred near N44 and N119. They are nebulae in which (some of) the gas is ionized, i.e. the atoms have lost one or more electrons by the action of energetic ultraviolet radiation emitted by very hot and luminous stars in this area. Both of these nebulae are seen in front of rich star fields in this galaxy in which there are also several stellar clusters.

These photos are based on exposures made through three optical filtres, including a narrow-band one centred on the H-alpha spectral line from hydrogen (wavelength 656.2 nm in the red part of the spectrum; light of this wavelength is emitted when protons and electrons combine to form hydrogen atoms). The red colour therefore traces the extremely complex distribution of ionized hydrogen within the nebulae. The present reproductions enhance this colour in order to show the fainter structures. Note also the very different colours of individual stars, mostly reflecting their temperature, from the hottest (blue) to the coolest (red).

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