The Astrology of Space - Matrix Software

The Astrology of Space
A nebula containing a very hot star can be excited to
self luminosity, resulting in what is termed an
emission nebula. A nebulous region which is excited
to luminosity in this way is also called an H-II region
since hydrogen (H) is the most abundant element.
Emission nebulae are huge masses of gas that
absorb ultraviolet radiation from nearby hot stars and
reradiate it as bright-line emission. The most famous
example of an emission nebula is Messier Object 42
(M.42), the great nebula in Orion. Another is the Eta
Carinae Nebula in the southern sky. The larger
emission nebulae are most often associated with the
very hot "O" and "BO" stars and may contain dense
groups of these most luminous stars. The hot central
stars in the emission nebulae often appear to have
cleared away the dust from their immediate
surrounding, creating a hole or dust-free bubble inside
an otherwise dusty region of space (see the section
on Solar Wind).
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