OBSERVATORY DISCOVERED SIX "NOVAE" IN LAST SIX MONTHS

During the past six months six new stars or "novae" have been discovered at the Harvard College Observatory. These interesting objects have been found by comparing photographic plates taken at the Observatory recently with other plates of the same region of the sky taken at earlier dates. In this way the appearance of any new object or the sudden brightening of a previously faint star is rendered conspicuous. The remarkable results that have already been obtained since Professor Bailey instituted the systematic search of the Harvard plates of the Milky Way region is another instance of the valuable policy of the Harvard Observatory in photographing the entire sky at short intervals. The collection of astronomical photographs now in the Photographic Library of the Observatory numbers over 250,000 glass plates and contains the only existing history of the stellar universe for the past 30 years.

Novae Appear Chiefly in Milky Way.

Three of the novae recently discovered have been found by Miss Mackie, and three by Miss Woods of the Observatory staff. It is a most interesting fact that nearly all novae discovered are found in the region of the Milky Way, and those recently found have appeared in the region of the Galaxy between 16 hours and 20 hours of night ascension or in the neighborhood of Sagittarius, a summer constellation which rises now a little before the sun.

Perhaps the most plausible explanation for the appearance of a novae is the collision of a dark star with another, or with a dark nebulous mass. If such is the case we should well expect collisions to occur most frequently in the region where stars and dark nebulae appear most abundant, as is the case in the neighborhood of the Milky Way. The discovery of a nova is always one of the more spectacular results of astronomical research which never fails to arouse popular interest. None of the recent discoveries can be found with the naked eye, their magnitude ranging between six and seven. The most recent nova bright enough to be seen with the naked eye was Nova Aquilae Number 3 which suddenly burst into brightness in June, 1918, and was visible as a star of the first magnitude for several nights, gradually fading, however, until by the end of the year it had disappeared as a naked eye object.