Prevalent Misconceptions
The general idea of an astronomer’s work, as gathered from the
questions and remarks of visitors, is that he sits at the eyepiece of
the telescope sweeping the heavens in a search for new planets, comets
or stars. The absolute futility of such a use of the telescope is
evident when it is realized that the main field of the 72-inch covers
only about one hundred-millionth of the sky and if only five seconds
was required to examine each field it would take more than a lifetime
to go over the whole sky once. A second misconception is the idea that
large telescopes are used for visual observations of the planets with
special reference to their habitability. No work is being attempted
at this or other large observatories on planetary detail for which
about an 18-inch refractor gives the best results and such a large
telescope as the 72-inch is quite unsuited. All scientific observations
with the 72-inch are made photographically and it is only arranged for
visual use on Saturday evenings when for two hours visitors are allowed
to observe the heavenly bodies. A third misconception is that the
astronomer only works at night. However true this idea may have been
in the days of visual observations when the measurements were made at
the eyepiece, there is certainly now, when photography is so generally
applied, more day than night work in astronomy. Besides the advantages
of permanency, accuracy of measurement and power of recording objects
beyond the range of the keenest eyesight, the photographic method has
the further great advantage that an hour’s exposure may give sufficient
material for several days’ measurement and discussion.
Spectroscopic Work
As already indicated most of the work with the 72-inch telescope
is spectroscopic, but as also indicated modern spectroscopic
investigations cover so wide a range of research that the actual work
of the observatory is very varied. By aid of suitable spectrographs
attached to a large telescope we can measure the speed of the stars
towards or from us, their radial velocity as it is termed. We can
discover double stars too close ever to be seen double in any telescope
and we can determine the manner in which they revolve around one
another and their distance apart and mass. From the spectra of the
stars we can determine their absolute brightness as compared with the
sun and their parallax or distance. The chemical elements present in
the outer atmospheres of the stars can be determined and the pressure
in these atmospheres. The measurement of temperatures and other
physical conditions in the stars by means of the spectroscope is now
an accomplished fact and one of the most recent developments of the
spectroscopic work here has been to provide evidence of the truth of
a theory of atomic structure and to show that the atomic constants in
the enormous furnaces of the stars are the same as on the earth. Such
a catalogue of information, obtained from an investigation of the mere
quality of the light from stars so faint as to be quite invisible to
the unaided eye and so distant that it may take thousands of years
to travel to us, is sufficiently comprehensive to be treated in more
detail.
Radial Velocities
When the 72-inch telescope was in course of design and construction,
one of the greatest needs in astronomical work was increased data in
regard to the radial velocities of the stars. Although the telescope
was so designed as to be suitable for all kinds of observational
work, special attention was devoted to the spectroscopic end. After
consultation with the most prominent astronomers an observing programme
of about 800 stars whose “proper” or cross motions across the sky were
accurately known but whose radial velocities had not been determined,
was prepared and spectroscopic observations of the stars on this
programme were commenced as soon as the telescope was completed in
May 1918. After slightly over three years’ work, observation and
measurement were completed and Vol. II, No. 1 of the observatory
publications, “The Radial Velocities of 594 Stars,” was published early
in 1922. As hitherto the radial velocities of only about 2,000 stars
had been obtained, this work was a considerable addition to existing
data about the motions of the stars and will be of great use in
extending our knowledge of the structure and motions of the universe.
A second programme of 1,500 stars has been prepared but owing to other
intervening observational work, not much has yet been done on this new
programme.
One of the auxiliary programmes undertaken and nearly completed since
the first programme is the determination of the radial velocities of a
very interesting but limited class of stars, the highest temperature
stars known, the O-type stars. The radial velocities and other
interesting data about 50 of these stars have been completed.
Spectroscopic Double Stars
In the measurement of the radial velocity of the 800 stars on the
first programme it was found that in about 180 stars successive plates
did not give constant velocities, the stars at one time approaching
at another receding from us. This phenomenon is practically certain
proof that we are measuring the velocity of a star revolving around an
invisible companion and such stars are generally called spectroscopic
binaries to distinguish them from visual binaries which can be seen
double in the telescope. Over 200 spectroscopic binaries have been
discovered at this observatory as compared with about 700 discovered
elsewhere, again a considerable addition. In about 20 of these
binaries, observations were continued until the period of revolution,
the form of the orbit, the separation of the two stars and in some
cases, their masses were determined. In a particular class of
spectroscopic binaries, the eclipsing variables, which allow from the
combination of spectroscopic and photometric measurements the absolute
dimensions to be obtained, we were able to determine the separation of
the two stars, their diameters, densities, masses and brightnesses and
the probable distances. Such complete information has been obtained
here about seven systems, while only seven other systems have been
determined elsewhere.
Absolute Magnitude and Distance
A new application of spectroscopic methods is to the determination of
the total brightness of the stars as compared with the sun and their
distance or “spectroscopic parallax” as it is called. This depends not
on the positions but on the relative intensity or strength of the lines
in the spectra of the stars and has only been developed in the last
three or four years. The absolute magnitude and spectroscopic parallax
of about 800 stars is now nearly completed and will soon be published
while as a side line the radial velocities of 125 more stars have been
determined.
Physical Conditions in the Stars
The spectrographs have also been used by one member of the staff in
the determination of the physical and chemical conditions in stellar
atmospheres, a new and difficult problem but one which promises not
only very valuable additions to our knowledge of the constitution of
the stars but may also lead to economic applications of the greatest
importance. A new method depending upon the use of a wedge of dark
glass has been applied to determining the distribution of energy in the
different parts of the spectrum of the stars and to measuring their
temperatures, while an application of the same methods to individual
lines may lead to a great increase in our knowledge of conditions in
the stars. A special investigation of three of the high temperature
O-type stars referred to above has proved the existence in the spectra
of these stars of lines predicted as present from purely theoretical
conditions but never previously identified and has thus remarkably
verified a theory of the structure of the atom. The measurement of the
wave lengths of these hitherto unknown lines has led to an important
independent determination of the fundamental constants of atomic
structure and the dimensions of the atom and has shown that these
constants and dimensions are the same in the tremendous furnaces of
the stars as in our terrestrial laboratories, a verification of the
homogeneity of matter and the uniformity of physical laws throughout
the universe. Further interesting results from this investigation
are the application of a new theory of ionization with the probable
relative abundance of the elements to an independent determination of
the temperature of these stars.
Other Investigations
Direct photographs have been made of some nebulae and clusters but
this work is not being definitely followed at present. Investigations
into the phenomena accompanying some short period binaries have been
made and into the behaviour of the two strong calcium lines H and K
in the spectra of the high temperature stars from which interesting
and valuable results are expected. Since the observatory commenced
work two bright novae or new stars have appeared, which have been
fully observed spectroscopically here and the results discussed. The
plates of the nova in Aquila have been loaned to the observatory at the
University of Cambridge, England, for fuller discussion and analysis.
Value of Astronomical Work
This brief sketch of the work of the observatory naturally leads to
the question frequently asked of astronomers:--What use is the work
done at observatories and what practical value can a knowledge of the
stars have in everyday life? While astronomy has obvious practical
applications to navigation and surveying yet nine-tenths of modern
astronomical research is devoted to the more or less abstract question
of the constitution and motion of the stars and the structure of the
universe. Indeed most physical and chemical as well as astronomical
research is undertaken for the purpose of increasing our knowledge
and of investigating the secrets and laws of nature and has generally
no direct practical economic application. But it is now generally
recognized by the layman as well as the scientist that without abstract
there can be no applied science and that all the great economic and
industrial applications of science have had to be preceded by the
abstract and apparently non-practical investigations of pure science.
The Great War perhaps made more evident than ever before the absolute
dependence of applied science upon the unselfish and abstract work of
pure science.
Economic Value
In view of past experience in science it would hence be a rash
prediction to assert that the investigation of the conditions in
distant stars can have no practical application upon earth. It may be
of interest to point out one possible application of astrophysical
research.
It is generally agreed that one of the most important economic
problems of the not far distant future will be the provision of
sources of energy to replace our rapidly depleting supplies of coal
and oil. It appears now that the most probable solution of this
problem will consist in the development of some method for utilizing
the inexhaustible stores of energy contained in the atoms of matter.
Modern research on conditions in the stars has made it practically
certain that the enormous supply of energy, which has been radiated
into space for aeons of time from these bodies, can only be maintained
undiminished by the energy released by the transformation of atoms
in the interior of the stars, where conditions of temperature and
pressure prevail at present unattainable in terrestrial laboratories.
The most hopeful line of attack upon this tremendously important
economic problem hence seems to lie in the systematic astrophysical
investigation of conditions in the stars supplemented by physical and
chemical researches on the structure of the atom.
Ethical Value
While astronomers and scientific men generally fully realize the value
of the practical applications of science, their main purpose is the
search for truth and the extension of our knowledge of nature. While it
is possible that investigation of the stars may have immense economic
value, it is certain that it has tremendous ethical value giving us a
clearer knowledge of the laws of nature and of our relations to the
wonders of creation. Astronomy is the oldest and in many respects the
most important of the sciences and its study, through the ages has
been one of the most elevating influences on human character. Poincaré
has well said that if the earth had been so continuously covered with
clouds that the heavenly bodies could not be seen, mankind would still
be in a primitive state and under the domain of superstition. The main
superiority of modern over ancient civilization does not consist in the
greater abundance of the necessities and luxuries of life, although
this is undoubtedly due primarily to scientific research, but to the
elevating influences of the truer conceptions of nature made possible
by the abstract study of astronomy and other sciences.
It has been truly said that the degree of civilization of a country may
be judged by the support it gives to the study of astronomy. By the
establishment and maintenance of the Dominion Observatory at Ottawa
and of the Dominion Astrophysical Observatory at Victoria with the
second largest telescope in the world, Canada has a just claim on this
criterion to the favourable estimation of the scientific world.
VICTORIA, B.C.,
May, 1923.
TRANSCRIBER’S NOTES:
Italicized text is surrounded by underscores: _italics_.
Obvious typographical errors have been corrected.