The Portland daily press., 1897-01-01
CLASSIFYING THE STARS.
A Task Undertaken by the Allegheny OBJ
servatory.
(Brom the plttsburg Press. }


Few persons are aware of the fact that
within short distance OF the busy CEN
ire of Pittsburgh's industry at least one
man is devoting his attention to the
classification of the stars. Yet this Is
what Prof Koeler of the Allegheny OBJ
seryatory is doing, and his work in this
line has brought him to the front rank
among scientists and has made the Allie
gheny observatory better known in the
scientific world than it is at home.
During a visit to the observatory few
mornings ago the writer found the Pro-
fessor In the library devouring some
treatise about the stars. AS he sat smok-
ing ne was soon in the midst of most
interesting talk about his work, ana
some very valuable information was
given, which will no donbt be of general
interest to the public.
The first attempt at classification was
made by the astronomer Herschel, who
grouped them according TO their colors,
the only method then possible, when the
speotroseope and all the marvellous reve-
lations that follow in its wake had not
yet come into view on the horizon or the
scientific word. The first Classification
by means of the new invention was due
to Rutherford of America and Gekchi OF
Europe. BY them the stars were divided
into four distinct types or classes.
To the first class belong the minority
those stars of white or blush cast,
like Sirius and Vega. These stars show
on the spectrum very dark lines of hydro
gen, broad and diffused and shaded
toward the edges, with very faint and
narrow metallic lines, not easily SEEN
In other words, the lines on the spec
trum give evidence of q dense hydrogen
atmosphere surrounding the stars. There
Is now reason to suppose that the tiny
stars in tho milky way also Belong TO
this Glass They are the hottest OF all the
heavenly worlds.
To ths second class belong all those Of
"a yellowish color. These ara not so hot
as the others and there ara not so many
of them, 10 this class belong the stars
Arcturus, Carella, and our own sun.
And 1t is just here that curious COM
parison presents itself II our OWN sun,
shining as IL does with such enormous
heat, belongs to the class OF yellowish
color and cooler temperature. how in
conceivable must be the heat If those that
shine with white and blue light. The
speetra of the second class Indicate hydro
gen, but not in such great quantities.
They also give evidence of many other
metals, such as iron, calcium, &c. 10
the first class belong more than haif OF
the visible stars while the first ana sec
ond together comprise seven-eighths Of
all of them.
To the third class belong those of the
orange and fred hue. They are much
more in the minority than the second
class, but their spectra are the most
strongly marked and the most beautiful
of all. They include those stars krown
as Betelgeuse and Aldha Hercules. The
chief characteristics Of their spectra are
the bands Indicating the EXISTENCE of
many compound substances. They are
enyeloped in al atmosphere charged with
many metallic vapors, while tho orange
| color is accounted for by the exceedingly
low temperature.
| 1t is with this class'that Prof. keeler
| of the Allegheny observatory Is now
chiefly employed. Whom speaking Of
them Prof. Keeier said "The most I'm
terestinQ feature of the third class is tha
| existence of chemical compounds in their
atmosphere. But they present the great
est difficulties In their study. when
| taking photographs of them, AS 1 nave
been doing of late, orthochromatlc plates
must be used and the exposures must be
very long, SO that the adjustments OF the
instrument are liable to change. have
| in the study of the orange -colored stars,
obtained some beautiful photographs. :"
They ure said to be the best that have yet
been obtained.
Strange TO say, 1t was in the study Of
the stars thas astronomers first dlscov-
cred from their observatories COM
plete study of hydrogen, before such u
spectrum had been obtained in the labor
atories of the earth. Several years ago,
by the lines of It's spectrum, astronomers
recognized the existence OF strange ele-
ment, which they named heiium. In the
SUD- in the stars themselves, ana aftor-
ward in the nebulae, the same line was
found In the Allegheny and LICK oo-
servatories, in 1893, this element was
found in the stars In tho constellation OF
Orion. At this time helium was an ele-
meut not to be found on TIE earth
bout year ago, however Prof. Ram
say, while at work in his laboratory. dis
covered that the cnIth was the possessor
of the heavenly helium. This Was II dis
covery of the greatest Importance to as
tronomy. II had been Fsought for many
years. and some ona wittily remnrkod at
the time that Ramsay had at last sue
ceeded in running helium to earth. "
Many other elements, too, there are
that are of tho stars, but not OF the Gearth
while even our own sun Is known, by
means of the spectrum, to contain certain
ele nents not vet found on tho earth. 1t
is in search of these that scIentlnc men
are now engaged. Taxing 1or granted,
as they do,. that the sun ana lts planets
have had q common origin, as required