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Lump Star

NGC 2023

Proper NameLump Star
Messier NumberNone
NGC/IC NumberNGC 2023
Other DesignationsLBN 954
Right Ascension5h 41m 38s
Declination-2° 15' 52"
Distancec.1,500 light years
c.500 parsecs
MagnitudeApparent: +10.00
Absolute: +1.64
DiameterApparent: 10'
Actual: 4.5 light years
Associated Star(s)HD 37903
Optimum VisibilityDecember / January
NotesThe young blue star HD 37903 lies within the fringes of the vast dark Orion Molecular Cloud that fills much of Orion. In the region around the star, the hydrogen of the Cloud is illuminated to create this roughly circular patch of blue-white light near the base of the Horsehead Nebula.

The Lump Star nebula in Orion, showing the Horsehead Nebula to the southwest against the long, pale backdrop of IC 434. The brilliant star in the extreme northwest is Alnitak, the easternmost of the three stars of Orion's Belt Imagery provided by Aladin sky atlas

The Lump Star is not in fact a star at all, but a bright nebula in the constellation of Orion. It lies in the same general area as the star Alnitak and the Horsehead Nebula, close to the 'base' of the famous dark horse-head shape.

The nebula represents a small part of the vast dark Orion Molecular Cloud, visible because it reflects the light of new stars forming in this region. The result is an approximately circular area some ten arcminutes across (that is, its diameter is about a third that of the Moon's disc in the sky). In reality this nebulous region covers a region of space some 4½ light years across.

The blue-white light that illuminates the Lump Star comes from the newly-forming stars within it. There are about twenty of these stars and protostars, but the light of the nebula is primarily generated by a star designated HD 37903. This is a very young blue star, still enveloped in the gases of the Lump Star nebula where it came into existence.


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