The Astrology of Space - Matrix Software

The Astrology of Space
Semi-Regular Variables
The semi-regular red variables form a group that
grades into the long period variables. They have
similar periods and spectra, but their ranges of
brightness and their spectral class are much smaller.
These stars may be considered cyclic rather than
periodic. The lengths of individual cycles and the
forms of individual light variations are much more
irregular than for the long-period variables, which in
turn are less regular than the Cepheids. The semiregular
red variables may be on the verge of
becoming long-period variables. This group contains
a number of super-giant M stars, such as Betelgeuse
and Antares, with absolute visual magnitudes near 4
and a large enough angular diameter to be measured
with the interferometer.
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