The Bourbon news. [volume] (Paris, Ky.) 1895-19??, 1922-04-18
New Method Being Employed by
Astronomers at Harvard
College Observatory.
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BASED ON STUDY Of SPECTRUM
Vast Collection Of Photographs Nov
Being Used and Exact Figures
No Longer Depend on
Old System.

are now being measured for the first
time at Harvard College Observatory
by recently developed methods based
upon study Of the spectrum. It has
been found that the huge collection
of photographs Of star spectra, as
sembled at Harvard during the past
generation and numbering over &c.,
GOO plates, can be put to new use
In determining the distance of stars,
and the work q m measurement is go
ing ahead rapidly. s,y:,ssy:,s
Many Of The vast humber Of stars
whose distances are still unknown are
the bright. comparatively nearby
southern stars, because nearly all the
observatories where stellar distances
are measured are located in the north
ern hemisphere. The Harvard astron-
Omers are therefore concentrating
much Of their attention upon phetO-
graphs of southern stars at the Har-
ward station at Arequipa, Peru.
New Method.
The new methods of measuring the
distance Of a star by study Of Its
spectrum are based upon discoveries
by a number of astronomers. A re-
markable contribution to the subject
has been made by DR.. Neigh Mad Saba,
an East Indian, who is assistant pro-
fessor Of physics in the University of
Calcutta.
Until recently the only available
method for measuring star distances
has been the parallax method, which
consists Of triangulation, using the
diameter Of the earth's orbit as base
line In other words, observations Of
a star are made at intervals Of about
six months. During this period Of six
months the observer Is carried by the
motion OF the earth to a point some
1873 million miles from that Of his first
observation, and using this distance
as base line he can work out the
distances Of the nearer stars.
Almost all the stars, however, are
so vastly remote from the earth that
even with. q base line of 186 million
miles their distances cannot be trian.
gulated.
1t is for these more distant stars
that the new methods are used. Al
the Mount Wilson observatory, w. s
Adams and his associates have sue
ceeded in developing a procedure de-
pending on the lines In the spectra OF
stars as photographed with large tele
scopes fitted out with powerful spec
trQscopes, The lines are due to the
absorption Of light from the stars
surface by the clouds of iron, nickel
calcium and other elements that form
it's atmosphere. DR.. Bertil Lindblad
has provided another method, baset
upon the examination Of the so-callet
"cyanogen" bands In the spectra
These new methods have been care
| fully checked by the older ones.
| The Next Problem.
Now that methods Of measuring
star distances from study of spec
ira have been worked out, standard
| lied and checked, the next problem i!
to apply these methods to those thou
sands of stars whose distances art
| still unknown. One Of the funda
mental tasks of astronomy is to de
termine how the stars are distributed
through space, and this can never b.
| known until the distances are meas
ured.
| 1t is this task of applying the new
methods for which the Harvard col
lection Of photographs Of stellar spec
ira has been found to furnish ex
cellent material u give single ex
ample, photographs made at Cam
bridge thirty-five years ago give thu
distance Of Alpha Ursae Matoris, on
of the pointers In the big dipper
as about seventy-two light years. Ii
other words the light now coming IL
from that star began its journey abou
1850, and the light photographed Of
4 the Harvard plates In 1887 started II
1916.