Survey of Galactic System Being Conducted At Oak Ridge Observatory Reveals New Facts

As part of a broad plan to determine the nature of the galactic system in which the solar system is a minute part, Dr. Eric M. Lindsay and Dr. Freeman D. Miller '30, of the Harvard Observatory, have been counting stars at the rate of 5,000 each day and have now completed almost half their task of classifying the estimated 10,000,000 stars of the thirteenth magnitude and above. The whole project is under the direction of Bartholomeus J. Bok, Assistant Professor of Astronomy, and Harlow Shapley, Paine Professor of Practical Astronomy.

The Lindsay counts of the southern hemisphere are about 75 per cent complete and several important deductions have already been made from them. It is shown that the local cluster in which we live is of a diameter not greater than 3,000 light years, while former estimates had placed it at about 12,000 light years.

For future reference in determining sky has now been mapped to show the number of stars of each magnitude in every section, and when the survey is complete 200 representative sections will be selected for use in an intensive study of spectra and color differences.

Of almost even more interest to the layman are the estimates made by Observatory officials as to the age of the system and the number of stars contained in it. The whole system is 100,000 light years across and 1,000 light years thick, formed in the shape of a watch, according to most recent data. It contains approximately 200,000,000,000 stars as determined by their gravitational attractions, but only about one billion are within range of the most advanced photographically instruments of today; while within a radius of 6,000 light years, which is the limit of the actual count now in progress, there are only about 10,000,000.

Sir James Jeans, it is asserted, is wrong in his estimate of 5,000 billion the magnitude of stars each part of the years for the age of the system. It appears to be much younger than that--probably only about 5 billion years, but there seems to be no reason to expect that it will disintegrate much for another 1,000 billion years.

The stars are actually counted from plates taken by small three-inch telescopes, which cover 16 square degrees of the heavens on each plate. The plates are then divided into quarter-inch squares, and the observer looks through a pair of binoculars to count the images within each square, finding as, many as three or four hundred in each. In this work, the large telescopes are useless since the greatest area it is possible to photograph with a 100-inch instrument is about one-tenth of a square degree.