The Astrology of Space - Matrix Software

The Astrology of Space
range from A to M and N . Those with the longest
period have spectra of the latest type and those with
the shortest periods tend to be A (or B) stars. Those
of longest period are called Long-Period Variables
and are red-giant stars. Stars with periods between a
day and fifty days or more, the Cepheid Variables, are
super-giant stars with spectral types near F or G at
maximum. Stars with periods less than a day, called
the RR Lyrae Variables, have spectral types between
A and F, and absolute magnitudes near zero.
Between the long-period variables and the RR Lyrae
stars occurs a less well-defined series of periodic
variables, with giant or super-giant luminosities and
spectral types between F And K.
The Cepheid Variables
The Cepheid Variables, so named because the
naked-eye star delta Cephei is a typical example and
first discovered, are all giants or super-giant stars.
The pole star Alpha Ursa Minor is a Cepheid variable.
The Cepheids are pulsating stars with periods ranging
from a few days to several months and spectral types
from F or G (at maximum light). All are reddest at
minimum light, but never of spectrum later than K.
The Cepheid variables are most important because
they are bright enough to be observed in other
galaxies besides our own, such as Andromeda. Since
we know that the Ionger the period of a Cepheid, the
more luminous it is, these variables have served as
the "standard candles" with which to explore external
galaxies such as the Magellanic Clouds. Over 600
Cepheids have been discovered in other galaxies, as
well as our own and this group of pulsating stars are
often called Classical Cepheids. Cepheids are
associated with dust filled regions of space.
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