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> N44 nebula in the Large Magellanic Cloud
N44 nebula in the Large Magellanic Cloud
author: ESO/Novapix
reference: a-neb80-44001
Image Size 300 DPI: 33 * 33 cm
This photo shows the southern part of the spectacular N44 region in the Large Magellanic Cloud. The green colour indicates areas that are particularly hot. North is up and East is left. The Large Magellanic Cloud is located in the southern sky at a distance of about 170,000 light-years. It hosts many giant nebular complexes with very hot and luminous stars whose intense ultraviolet radiation causes the surrounding interstellar gas to glow. The intricate and colourful nebulae are produced by ionised gas that shines as electrons and positively charged atomic nuclei recombine, emitting a cascade of photons at well defined wavelengths. Such nebulae are called "H II regions", signifying ionised hydrogen, i.e. hydrogen atoms that have lost one electron (protons). N44 in the Large Magellanic Cloud is a spectacular example of such a giant H II region. With a size of roughly 1,000 light-years, the peculiar shape of N44 clearly outlines a ring that includes a bright stellar association of about 40 very luminous and bluish stars. These stars are the origin of powerful "stellar winds" that blow away the surrounding gas, piling it up and creating gigantic interstellar bubbles. Smaller bubbles, filaments, bright knots, and other structures in the gas together testify to the extremely complex structures in this region, kept in continuous motion by the fast outflows from the most massive stars in the area. The colours reproduced in the image of N44, sample three strong spectral emission lines. The blue colour is mainly contributed by emission from singly-ionised oxygen atoms (shining at the ultraviolet wavelength 372.7 nm), while the green colour comes from doubly-ionised oxygen atoms (wavelength 500.7 nm). The red colour is due to the H-alpha line of hydrogen (wavelength 656.2 nm), emitted when protons and electrons combine to form hydrogen atoms. The red colour therefore traces the extremely complex distribution of ionised hydrogen within the nebulae while the difference between the blue and the green colour indicates regions of different temperatures: the hotter the gas, the more doubly-ionised oxygen it contains and, hence, the greener the colour is. The composite photo produced in this way approximates the real colours of the nebula. The colour picture of N44 in the LMC is based on three monochromatic images taken on 6 and 7 December 2001 with the Wide-Field-Imager (WFI) at the ESO/MPG 2.2-m telescope.
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