The Savannah morning news., 1900-10-12
VARIABLE ARs.
Easy one for Amateurs 60 Observe
and How 60 no ~.

and How 60 no ~.
From knowledge
II II sot years since Dnvli Fahricirs.
enc Of the earliest ohfer, ars ~ sun spots.
noticed that a star in the neck % cetus.
the whale which ne had observed .n Au-
gust. 1886 10 be Of the thir1 magnitude,
had disappeared BY October ghls appear
"a an observation o. great Importance.
since a. seemed 10 show that the Axc1
stars are not all Of them permanent but
that they might die out Seven years lat
er Baycr recorded o four magnitude tar
IN precisely the same position as that
which Fabricius had noted 20 have dis
appeared Here. however. the matter rest
"a for an entire generation and t. was
not until 1885 that Holwarda detected tho
star again a. o. the third magnitude in
December but found u disappear In the
following summer 10 rcappeir again ~ IN"
autumn This star. therefore pmicron
CetL which received from HclVeltus the
name 81 Mira. the wonderful star was tho
hrst 20 become known as periodic Narl-
abie
The first star. that Is 10 say. in historic
times There h another more striking
oven than Mira. which u seems likely was
noted by the forgotten astronomers of
Arshla or the valley 81 the Euphrates
centuries before even Hinparchus anh
Ptolemy compiled their catalogue This
h BETA in the constellation Pcrseua. de-
scribed bv ptolemy as the principal star
In the head OF tho GorEon Me
dusia. which the hero Is repie-
scented a. carrying IN his hand This star
has como down to as from the Arabs
with tho name AiEol the Demon stir.
Dad
owed this name 20 the fact that though
ordinarily OF the second magnitude
sinks down almost 10 the fourth 40 per
fectly regular Intervals OF two days anD
twenty -one hours.
The variability Of Aigol was discovered
in modern times by Montauari IN 1863. ana
Il was rcdlscovered hy Goodricks In u.s.
The latter diseoyerer two years later ah-
ded two other variable G. inc let-hfia
Lyrae with e period Of very nearly ihlr-
teen days. and Delta Cephci, with one 81
Ave and one-third days. A. this date
scarcely more than n century ago. these
four stars we're almost the only vari-
ahles known 10 ne. ana varlabes con
tlnued 20 be rare objects until the middle
81 this century Now their numbers have
been added 20 - greatly that the cata-
iogue prepared by Prof Chandler in 1895
comprises go The variability Of which o.
fairly well established. ana new memners
~ the class are being discovered every
month
The four stars hrs. mentioned are al
well IN view during the September nights
The most striking star with which 10 be-
gin h AiRol The student avoiding all ref
erences 70 Ephsmerides should look out
Al regular intervals and compare the
brightness Of AiRol with certain Of the
neighborinE stars. Ordinarily Alpha Per
sei will be- distinctly but not very greatly
brighter than our Variable. while Gam
ma. Delta. Epsilon and Zeta viii be- DIS
tlnctiy fainter 40 a little greater dis
lance are Alpha ana Beia Arietis the for
mer slightly brighter. the latter slightly
fainter than Algol Alpha ard Beta Tri-
anguii are az no great distance and are
good comparison stars when Algol has be-
gun 20 fade.
II Will not be long before the observer
will md that his star % undergoing 4
change and that IL no longer nearly RI
walls Alpha Perset or Gamma Andromedae
IN brightness Directly this Il noticed
systematic observation should be begun.
A star should be chosen reasonably near.
distinctly brighter than the variable. ana
second star distinctly fainter n is
usual among variable star observers %
estimate these differences IN steps
these steps" corresponding generally 90
about a tenth 81 magnitude though prob
ably the beginner will make his steps con
siderably larger tnnn this The central
prineiple. however is that two stars
should be- selected. ono Of which 20 the OH
server o. clear 20 be fainter than IN va
rlalble. aud the other brighter ard SCI
both Of them pretty near The variah. c
brightness. Tire student should further De
careful 20 record whcf her The difference
between the variable ard the tn'nter star
a. equal 90 or greater or less than The
difference between "a and the brighter star
Having made one set Of satisfactory
observations. the student should leave the
ftar for whils-say. Tor hair en- hour
and then make an entirely fresh sel ~
observations ii he should boz fortunate
enough 20 hlt upou the beginning - a
minimum hls second observation will show
him the star somewhat fainter than the
nret and the difference will become more
marked az y third observation. The en-
lire period OF decline sud recovery Tor
Aleo. Is nine hours. the light fading for
four and one-half hours remain
ana then gradually Increasing again Tor
another period Of four ana one-half hours.
The light changes therefore a. most
rsuia rate Al about two and one-fourth
hours before minimum or about the same
interval nfserward that r. TO say. when
tho change is about half completed.
The observation n a simp.e one. with 40
accessories OF brilliant lights Or pleasing
colors. Yet the young observer cannot.
We think. but experience real pleasure
when for the FIRST time his observation.
carefully and systema ilcaliy made aud
duly recorded. show him beyond a doubt
that he is witnessing the dimmng o.
,he Demon Star. that he b watching
geroas untold millions % millions of miles
% space che partial eclipse Of that Car
distant sun There will BE- sense Of
achievement greater and not less be-
causa A has been accomplished by his