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| « back to overview Nebulae | Load higher resolution (1800 x 1200 Pixel – 3000 x 2000 Pixel) | Object description |
Just north of the Orion Nebula, which is visible with its extensions at the lower edge of the picture there is a blue reflection nebula area, embedded in an H-II star formation area. The whole region, including the Orion Nebula, belongs to the large Orion molecular cloud Orionis A. This region is located at a distance of about 1500 light years from the solar system. NGC 1977 is the name of the large open star cluster and the brightest parts of the blue reflection nebulae, Sharpless 279 is the catalogue reference for the reddish H-II region. NGC 1973 and NGC 1975 are the catalogue numbers of the fainter blue reflection nebulae.
The interstellar dust here reflects most of the light of the embedded luminous young blue stars. Inside the reflection nebulae, the radiation of the stars is strong enough to ionize hydrogen gas and produce a fainter, reddish emission nebula (Sharpless 279), which resembles the shape of a running man, see also this picture detail.
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The
hydrogen gas of the H-II region is mainly stimulated by the hot young star 42
Orionis (HD 37018). Other massive stars are the yellow giant 45 Orionis and the
variable KX Orioni, which contribute to the ionization of the nebular
region. NGC 1977 was discovered on January 18, 1786 by Friedrich Wilhelm Herschel and noted as "42 Ori and nebula" in his logbook. NGC 1981 is an open star cluster which is a little closer to the Solar System than NGC 1977 with a distance of about 1300 light years. It consists of only a few, widely spaced but quite bright stars, which are estimated to be only a few million years old. It is classified as type III 2 p (n) according to R. Trumpler. The star cluster was discovered by John Herschel on January 4, 1872. « The annotated image shows the size comparison with the moon. |
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