Evening star., 1938-10-25
NEW DOUBLE STAR
FOUND NEAR SUN
Two Virginia Astronomers
Report Observations at
Chapel Hill.
BY THOMAS r. HENRY,
Star stan Correspoudant.

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CHAPEL HILL, N. O., Oct. 25.-With
its nearest neighbor approximately
$1,000, 900 900 900 miles away, the sun
has at least 80 known stars within 4
radius Of less than 800 900 ,000, 900 900
miles. Drs. s. H. Mitchell and Dirk
Reuyl Of the Leander Mccormick OBJ
servatory of the University Of Virginia
reported to the National Academy Of
Sciences meeting here today.
Their recent observations, DR..
Mitchell said, restore little star in
the Southern Hemisphere named
Proxima Centauri. visible only with \
powerful telescope, to the position Of
next-door neighbor in space to the
solar system. It is 50 close that its
\ light reaches the earth in only three
years and four months, travelling at
The two Virginia astronomers are
engaged in a long time program OF
measuring the distances of stars within
the immediate space field of the sun
that is within from 20 to 80 light years
by means of their parallaxes, the
angles they make when considered as
the apex of triangle with the diam
eter Of the earth's orbit around the
sun as its base. This angle can be de-
termined by photographing a star at
different seasons when the earth Is on
opposite sides of its orbit. The angles
are always extremely small and the
work is very exacting, but, DR.. Mitchell
said, when the parallax can be deter
mined the distance of the celestial OBJ
ject can be calculated much better
than by any other known method. The
great majority of the stars are SO far
away that it probably would be i'm
possible to get parallaxes for them.
Spectroscope Now Used.
This old-fashioned surveying meth
Cd OF measuring star distances has
largely given way in recent years to
more spectacular types Of measure
ment by means Of the spectroscope.
With this method it is possible to
reach for almost infinite distances
into space but the distance measure
ments can be only rough approx
nations.
The vast majority of the stars are
so far distant that difference of
few trillion miles in an estimate
doesn't make much difference, but it
becomes important for stars close to
the sun. Some months ago. DR..
Mitchell explained to the National
Academy, spectroscopic observations
were reported which indicated that an
obscure star designated on maps OF
the heavens as Wolf 424 was much
closer to the earth than any other
celestial object except the sun and the
other planets. Its parallax proved
very difficult to measure, but DR..
Mitchell and DR.. Reuyl have now de-
termined that it is slightly over Is
light years away and that 80 known
stars. including Sirius the brightest
object in the heavens, are closer
neighbors
Next to Proxima Centauri, they have
determined, the nearest stars are two
companions in the same southern
neighborhood, Alpha and Beta Gen.
tauri. It takes light about month
longer to reach the earth from them.
Alpha Centauri, a star Of about the
size and brightness of the sun, held
the position of the suns nearest
neighbor for almost a century after
its discovery.
New Double Star.
The Virginia astronomers announced
today the finding purely by the photo
graphic method used in their parallax
observations of new double star
within the suns immediate neighbor-
hood. This star. known as Ross ga,
Is about 100000, ,OO0, 900, 900 miles dis
tant from the earth. 1t wobbles mark
edly in its path, they found. This can
only be explained by the fact that it
has close companion whose gravi-
.ational attraction is pulling it out of
a straight path such as all celestial
objects follow when nothing interferes
with them. The stars presumably are
circling around each other in a period
of about IS years. From the magni-
tude of the wobble in the path of Ross
614 the size and mass of the other
star, which never yet has been seen in
the telescope, can be calculated. It
probably is small star which radiates
very little light into space.
Many double stars have been found,
DR.. Mitchell said, by other and less
exact methods, but this is the first
time in the history of astronomy that
such phenomena has been revealed
by differences in position on photo
graphic plate.
While the three "Centauri stars"
are by far the closest neighbors of the
solar system. they cannot be detected
from latitudes north of the Equator.
The nearest star telescopically visible
in the Northern Hemisphere, DR..
Mitchell said. is Barnards star, an
object with the greatest proper mo-
tion of any known celestial body,
which Is six light years away from the
earth.
Distances of 1850 Stars.
Drs. Mitchell and Reuyl reported to
the National Academy on trigonometric
measurements of the distances Of 1,250
stars. All the bright stars in the sky
irrespective Of color and 20 degrees
south declination have had their dis
tances measured at the Mccormick
Observatory. At present, efforts are
being concentrated on faint stars with
very large proper motions.
New forms OF life, sprouting in the
depths of the infinitely little, constant
ly are threatening mans food supply.
This recently recognized phenome-
non explains the seemingly never-end-
ing fight against the blights and rusts
which attack grains and vegetables and
cause enormous losses every year, DR..
e. c. Stakman of the University of
Minnesota told the academy last
night.
1t has long been observed, Prof.
Stakman said, that as soon as one
plant pest seems to have been con-
quered by the breeding of an immune
species, another appears to take its
place and all the work must be done
over again. Thus the plant breeders