TWIN SUNS

Evening Star, Issue 18053, 22 August 1922, Page 6

TWIN SUNS

FIFTY-TWO QUADRILLION MILES DISTANT. THE LATEST DISCOVERY. A-tiuiiomy, tho oldest of sciences, is constantly bringing to light new heavenly bodies to add to tho wonders and the solemn mystery and fascination of human research. The latest discovery, characterised as the ipost outstanding" event in recent astronomical development, is that of twin suns iifty-two quadrillion mile® from tho earth. No human brain can conceive the immensity of this distance. One quadrillion is a million multiplied by iteclf four times, and is represented by tho figure 1 followed by twenty-four noughts. Tho wonderful discovery has been made by Dr J. 'b*. Plaskett, director of the Canadian Astro-physical Oliscrvatory, and probably tho most distinguished astronomer in Canada. Dr Plaskett, according to the cablegram, estimates that those suns burn at a temperature of 30,000dcg Fahrenheit, and whirl round ono another. The more massive is iScventy-fivo times the bulk of our eun; the second ono sixty-six times greater - in bulk. T..c !,.■ ■ ono is 15,000 times, 'and the smaller one 12,C00 times, brighter than onr sun. The larger of the new suns is more than five times larger than any other known heavenly body.

Dr R. K. Young, astronomer in the observatory of which Dr Plaskett is director, is at present in Sydney, cu route to Wollal, in company -with Professor Chant, in order to witness tho solar eclipse, and is peculiarly fitted to speak, not only of Dr Haskett's great work in the field of science, but also of this latest discovery of what might with all truth ,bo termed " the heavenly twins,” so remote from us that it would take probably between: 300 and 400 year's for light to (ravel from them to the earth. The contrast is the more striking when it is 'realised that it takes between eight and nine ■minutes, according to Dr Young, for light to travel from tho sun to the earth. Dr Haskett, it is stated, has been making a special study of early-typo stars, or stars, in other words, in the early stages of development—stars that precede onr own sun in their life history. Dr Plaskett, in fact, has made a study of the very earliest -types—very massive stars, for tho most part. The determination of the mass of a star is a very difficult problem in astronomy. “In fact,” says the distinguished scientist who is accompanying Professor Chant, “wo know the masses of very few of the stars, for it is only when the star happens to be a spectroscopic binary (as, for example, in the case of the present twin suns), or happens to be a visual double star whoso period of revolution and distance aro known, that we can. really get any idea of the mass of a ,star. Of the mass of the ordinary stars we cannot form an idea. It is known that many of the stare in the sky aro binaries for twins)—two stars of comparable mass, ono revolving round the other. Dir W. W. Campbell, who proposes to view the eclipse_ in Australia, and .who introduced many improvements in tho spectroscope, discovered _ a great many of tho spectroscopic binaries in his surveys of the skies. EARLY-TYPE STARS. Tho observatory with which Dr Plaskett and Dr Young are associated has been making a special study of these binaries for a number of years. The- observatory has been able, not only to determine a great many of the orbits, or paths, of those heavenly twins, but also,_ from its observations, to ascertain data in respect to revolution, the projected distance of the stars apart, and the shape of the orbit, as well as the angle of it in space —that is, how it is inclined towards us. Tho observatory, in the course of its surveys of tho skies, has now and again como across striking orbits, and has been in a position" to get an idea of tho mass of the stars.

It is in tho course of tho survey of tho early-typo stars that Dr Plaskett lias been undertaking that ho has been able to chronicle another notable event in astronomv by the discovery of this spectroscopic binary, which is more popularly known as tho twin suns, and which, in relation to mass, stands at the very head of the list, the bigger of the new suns, according to the cablegram, being more than five times larger than any other known body. A discovery such as this is always of deep interest. It.is interesting to know, in The case of masses of stars, what the average mass is, and as soon as that is determined, scientists aro interested to know how they depart among themselves from the- mass. For instance, they may be alike, and yet have an average. The average mass of the stars, it is stated, is about the same. LIFE OF THE SUN. A question by tho reporter relative to the sun, as one of tiio ordinary stars, Dr Young followed up with an interesting statement, indicating the fading splendor of tho sun. “The sun,” he remarked, “is about an average star in mass. It is far below the average star in brightness. The sun, as a matter of fact, belongs to the class of stars called dwarfs—not dwarfs in mass, but dwarfs in 'brightness. It is on the downward scale of its life, and is burning out. It has already reached its peak in brightness, and is fading, and will probably grow fainter and fainter as it dies out.”

The pressman’s cariosity to know more about this portentous happening caused Dr Young to smile. Ho was satisfied simply to givo the comforting assurance that tho sun will last many millions of years, even if it has reached the zenith of its refulgence and glory. Tho gun—our star, in a sense—only appears so brilliant in its splendor because of its relative nearness—it is onlv 93,000,000 miles away—the distance of the stars being of tho order of millions and millions of miles. “ There are stars in the sky,” says Dr Young, “ which would outshine the sun hy probably 10,000 to 1 if they were placed at the same distance.” TYPES OP STARS.

Tho sun, which is now attracting so much attention because of the coming eclipse, is, in the scheme of things, ns astronomers understand it, of the “G” type. The stars, according to Dr Young, are classified “O,” “B, “A,” “F,” “ G,” “ K,” “ M,” “N.” Those coming within the category of “O” and “B” are tho early types, Dr Plaskott’s discovery being of the “O” type. “This type,” says Dr Young, “is very big, of very low density, and very hot, ana very frequently of largo mass. Their average mass is probably eight to ten times that of the sun; this particular ono is over 100 times. Our sun comes in about the“G” class, about halfway down the scale. Tho early types aro blue to look at, later types fainting gradually towards red, indicating probably lower temperature.’ Why aro tho stars so faint? “The nearest star,” says Dr Y’oung, “is nearly half a million times as far awav as the sun, and that is why they are faint. The sun looks big simply because it is comparatively close.”