The Seattle post-intelligencer. [volume] (Seattle, Wash. Terr. [Wash.]) 1888-1914, 1899-10-06
|MN TREE NeIn Sims.
eowO ~ Tu1 WWWOU01Vk -
SUa1s ~ oOsoovATsoN.
. kWss1 DsD1oessees - ~ ees -
sAs sessssssss0s - 0svsssss0 -
DsesssSs ~ 0sevsseS Ds1sss
go ehewtoO Tn~tS Ms~s0ssss.

rw many vssss scientists have ksows
~ sbs ssssssNes - fsssf companion %
the Nsysh star. - etSss ssd faint 70 iris
hsss ofsss wseA n - test me power ~
sbSs Svss sNA Sssssv0ssfs News MS
lately sens FROM me fAgt observatory ~
Mount hamilton. California. ~ ths dc
esvevy inst Hoiasts CONSISTS ~ three sssss.
swe ~ which sevotvs around coW@on
center ~ Grsvisy sn-sbopt f5ur days ~
me aaNe time sbsss two ssvolve AROUND .
third sssf In much me same Wsy - tbs
ssrsb srd mson ssvoiys around the sun
IN ft'- ~sse the test - - severe tbst No
sSissf ~ ean see me Individual stars.
VIZ ran oniy infer their sSistsncs ~ no.
tsrjDG . peculiar Dhenomsnon In sbs spec
trvm Of toIAris
The sssrs, snd. In fact. sn Ismsnous
beAssA emit . series Of waves. which srs
tSpssm1tssd BY the ether 70 20. Those
waves that fall apSn the fef!na % ovS
eyes produce . ssnsatIon thar We csll
light In the cass ~ many millions of
stan the effect Of sheoe waves upon our
e1ss n inapprecsable. without the aiA Of
some Instrument such stars are invisible.
1hH jenee 81 telescope eoudenses large
sfea Of waves Into . small comrssa and
this increases tho effect upon the eyes of
fhe observers. Consequently telescopes
light ~ 10 make exceedingly faint stars
visible 70 the observer
Hut light has another Characteristic -
sldee tntsnslty--shat n. color. When
csrtaln number Of waves satNr the sye
each second Ne call the sesviiinG ssnss-
tim red. When . larger nuabsS enter
each second W call the sensation violet.
etc. n the nsht ssshsssA By some large
tsiascop~ passes through prism. o.. bst-
ter. several prisms. the lidsSens coIors
are arranged IN the order Of thsiF wave
length. Such IN arrangement Of cotOrs
has besn named the spectrum.
The spectrum OF the sun and Of most Of
the stars n crossed BY . number Of One.
dsrk lines. These lines are really gaps
caused BY the absence Of rays Of light Of
certain wave lengths. The light. before
II can reach our telescope. has to pass
through an extensive solar atmosphere
which absorbs tertsin parts. The gaps
IN tks specsrum caused by atmospheric
Absorption Of the sun and stars are call
~ limos.
when . luminous body 10 at rest, the
waves 81 light are emitted In al diYec-
lions alike But when II n moving rap
tIy the waves IN front are crowded. whiIo
those In the rear are correspondingly
isnstheneh. OF course. NJ the sides the
waves continue 10 be emitted At their
normal wave length. The same phcnom-
press train whistles 40 II passes. tho
pitch Of the whistle In perceptibIy lower
when the train n rcceding than when II IN
approaching. Therefore. when the star In
approaching the earth With q sufficiently
large velocity. all the lines are displaced
q tr1ne toward the violet. that being the
color with the shortyt wave length.
Conversely. when the star II receding
from the earth the lines are displaced to-
ward the red end Of the spectrum. This
displacement In 10 exceedingly slight that
measurements Of It's amount have had lit
tie value until recently. The nrst success-
fui investigation on tho motion In the line
Of sight was upon the rotation OF tho
sun by vogei In 1911 Since then the spsc-
ira have been photographed and mcasur-
Cd. In this way dispiacements correspond
ing TO n velocity considerably less than q
milo per second can BE- detected.
II two stars are 10 close together that
they appear IN the telescope ~ u single
object, the spectra will be supertmposed.
No long ~ these two stars move away
from us. or toward us at the same rate.
the lines In this compound spectrum will
continue to maintain the same relative
positions. Hut II the twa components OF
n double star move In opposite directions
In such n way that one n approaching
while tho other In receding from the
earth. then the lines Of the two super
imposed spectra viii be displaced In OPP
positc directions. Sometimes only one Of
the components Of q binary star In bright
enough 10 be seem A. this star revolves
around the center of gravity between II
and It's dark companion II In sometimes
approaching and sometimes receding
from the earth. The lines OF spectrum
are therefore displaced nrst toward the
violet and then toward the red end OK
the spectrum. Hence when n star In found
whose motion In the line Of sight n va
risbie. II n justinabIe 10 conclude that
there II close 10 u q fainter companion.
The period Of revolution of such bodies
about their center Of gravity n. 81 course,
obtained directly from the obscrvat ions.
In 1887 q photograph taken At the Har-
ward college observatory Of the spectrum
Of Zcta Ursa~ Majous tthe middle star
IN the handle of tho dipper) was found 10
contain several double lines An cxamIna-
ton Of the photographs showed that tho
lines are sometimes double and some
times single. Evidently We have here q
double Mar whose compcnents are no
close together that no TELESCOPES can
show than as double stars. They are re-
voiving around q common center OF graz
ity In such = plane that when one II mp
preaching the other In recedinG from the
earth. Twice during every revolution
they are nearly In a line with the earth
They are then neither approaching nor
rsceding, the lines Of their spectra are
In 1uxta positien and appear single.
Beta Persci named Aigoi. furnishes an
example Of q binary star where only one
Of the componenss IN visible. vogel. at
PotsdAm IN ISIS. found from the dispiace-
ment Of the lines in the spectrum that
Aigol IN moving IN small orbit AT tho