Evening star., 1951-06-11
Studies of Double Sturs
Expected to Fill in Gaps
U. Of Virginia Observatory
Maps Invisible Companions
By Thomos R. Henry

By Thomos R. Henry
Approximately one of every four stars
II this part Of the heavens has an in
visible companion Star-too small ever
to be observed with any telescope,
especially since its feeble light is
drowned in the light Of the larger and
much brighter object.
About one of every Is visible stars
has companion which also Is visible.
In both cases the two stars are re-
volving both around their own centers
Of gravity like the sun and also around
a center of gravity common to both
OF them. The presence of invisible COM
panions can be determined, although
with great difficulty, by analyzing this
motion. Search for them is a major
activity at the Leander Mccormick
Observatory Of the University Of Vir-
gina, where approximately ten have
been discovered in the past 80 years.
In this field Of research, says DR..
Harold L. Alden, director Of the OBJ
servatory, lies the only chance of ever
discovering objects of the dimensions of
very large planets-that is, objects Of
less than twelfth the mass Of the sun
when they begin to emit light from
the energy of their own gravity. There
Is essentially no hope at present Of ever
finding an object the size Of Jupiter,
the suns largest planet with a mass
about a thousandth that of the star
itself, because its gravitational attrac-
ton on the sun Is far too small to be
observed over a distance Of trillions Of
miles.
Chi Draconis Studied.
For the past year intensive obServa-
ticns have been made Of the invisible
companion Of the star Chi Draconis,
a fairly nearby star from which light,
moving at speed OF about 10000
miles a second, reaches the earth in
al Lpronmately 80 years. This is a yellow
star a little bigger and brighter than
the sun The invisible companion was
first found by DIR. Alden himself 20 years
ago but remained unstudied until TINS
year when it was taken UP by Walter E.
Mitchell of the Virginia University STAN.
From it, the Mccormick observatory
astronomers hope, it will be possible to
get clearer picture Of this type OF dou-
BILE star, which apparently constitutes
one of the most abundant objects in the
great Milky Way galaxy. It has been
determined that the two stars are about
100,000.000 miles apart, but are so ar
ranged in space that, while revolving
around each other, they never eclipse
each other. This may be typical of such
systems.
But the primary object of the study
of this particular system, DR.. Alden
says, is that eventually such studies may
make it possible to count the stars max
ing UP the local system Of stars, includ-
ing all the stellar objects within few
light years of the sun in every direction.
It is expected to reveal types and
sizes of stars hitherto unknown as the
gap gradually is filed in between the
largest visible stars and the smallest
invisible ones whose existence can be
determined.
A new yardstick for determining
the age Of fossil human bones is pro-
posed by Smithsonian Institution an
thropologists.
A part of the fossilization process is
the bones slow accumulation OF the
element fuorine from ground water.
The amount accumulated depends st n
how much of the element is present IL
the soil where the bones are buried.
Tests have shown. however. that the
accumulation increases with time and
Is essentially the same for all bones
buried together at the same period.
Burial Complications Explained.
A major problem in anthropology Is
to determine whether human skull.
for instance, found mixed with bones
Of extinct animals is of the same age
as the animal remains. This greatly
is complicated by the human practice
of burying the dead. A man may &C
cidentally be buried by his fellows in
q middle Of deposit of extinct NAM
moth bones, and it then is easy to jump
to the conclusion that man and NAM
moth were contemporaries.
Now. according to DR.. T. D. Stewart.
Smithsonian curator of physical an
thropology, if animal and human bones
found together show relatively the same
accumulation Of fluorine there can be
reasonable assumption that both were
buried at about the same time. Other
wise, they cannot have been contempor-
aries.
Actually the test is not new. 1t was
first used in France in the 10th Century
but was forgotten until few years ago,
when it was revived by DR.. Kenneth Oak
ley of the British Museum of Natural
History. BY means of it, he was able to
establish relative ages Of some Of the
most controversial British fossil human
bones.
Between the time of the French and
British workers, DR.. Thomas Wilson, a
former Smithsonian curator of archie
ology, became interested in the method
and applied it to fossil man in North
America. He showed that man had
lived in the New World since the end
of the last ice age. For more than
half-century this evidence of mans
antiquity has remained buried.
nuee%;one rnd An.,,o..