The times. [volume] (Washington [D.C.]) 1897-1901, 1900-11-11
MANY STARS THAT VARY
Mysterious Heavenly Bodies That
Change Their Brilliancy.
Periodically Bright or Dull and At
Times Almost Extinguished-Sev-
Eye, But the Majority Are TeIe-
SCOPE - Some Recent Discoveries.

The catalogue of variable stars is con-
stantly being enlarged by new discoveries
| Of those once mysterious heavenly bodies
that are periodically nearly extinguished.
! only to shine out as bright as ever like
electric lights with an unsteady current.
The number of known variable stars
| multiply so rapidly now that it is almost
impossible to keep track Of them. The
| recent discovery at the Harvard Observa-
| tory that certain clusters Of stars con-
tain an extraordinary proportion of va
rabies increases the number of these lat
ter so greatly that the recording Of them
in an almanac has become an Herculean
task.
ut is a curious fact says a WELL
known astronomer. that the ancients,
notwithstanding the care with which they
observed the heavens, never noticed that
any OF the stars changed in brightness
The earliest record of such an observa-
tion dates from 1885. when the periodical
disappearance of Omicron Ceti was no.
ticed. After this nearly two centuries
elapsed before another case of variability
In a star was recorded. During the first
so systematized the study Of the variable
stars as to make it new branch of as
trOnomy. In recent years it has become
of capital interest and Importance through
the application of the spectroscore.
Three of the periodic variable stars are
plainly visible to the naked eye. and their
regular disappearance and temperance
may be noted by anyone who knows where
in the heavens to look for them. These
stars are Omicron Ceti, called also Mira
Ceti; Beta Persei. or Algol, and Beta
Lyrae. Eacn of these stars exemplifies
certain type or law OF variations.
1t was on the night of August IS, 1896,
' that David Fabrieius made the memorable
discovery of Omicron Ceti. although he
did not at first recognize its periodical
disappearance. But so extraordinary an
object could not fail to command the at
tention of astronomers, and the fact was
soon established that the star appeared at
intervals of about eleven months, gradI-
ally fading out of sight after q few weeks
Of visibility. Observations of more CT less
accuracy having been made Cor more than
two centuries the following facts respect
ing it have been brought to light:
In the first place, its variations are
somewhat irregular. Some times when
at it's brightest, it rises nearly or quite
to the second magnitude. This was the
case in October. 1898. when it was about
as bright as Alpha Ceti. At other times
it's maximum brightness scarcely exceeds
the fifth magnitude. No law has yet
been discovered by which it can be pre-
dicted whether it shall attain one degree
of brightness another at maximum. Its
minima are also variable. Some times
it sinks only to the eighth magnitude. at
other times to the ninth or lower. In
either case it is invisible to the naked
eye.
AS with other stars of this kind it
brightens up more rapidly than it fades
away 1t takes few weeks from the time
it becomes visible to reach its greatest
brightness. whatever that may happen to
be- 1t generally retains this brightness
for two or three weeks, then fades away,
gradually at first, afterward more
rapidly. The whole lime Of visibility will
therefore, be two or three months. OF
course it can be seen with Il telescope at
any time.
One OF the most singular things about
the star Oniicron Ceti is the variability
of its period OF disappearance If we cal
culate when the star ought to be at its
greatest brightness on the superstition
that the intervals between the maximum
ought to be equal, we shall find that some
times the maximum will be thirty or forty
DAYS early. and at other times thirty or
forty days late These early or late maxi
ma follow each other year after year, with
a certain amount OF regularity as regards
the progression. though no deinable law
can be laid down to govern them Thus,
during the period from 1lS2 to 1su0 1t was
from thirteen to twenty-four days late.
In 1912 it was thirty-nine days late From
1s45 10 1856 it was. on the average, about
a month too early. Several comparatively
recent maxima, notably those from 1885