Hawke's Bay Herald. FRIDAY, APRIL 29, 1892. HOW STARS ARE FORMED.

Hawke's Bay Herald, Volume XXVII, Issue 9267, 29 April 1892, Page 2

Hawke's Bay Herald. FRIDAY, APRIL 29, 1892. HOW STARS ARE FORMED.

-•,_• it r* a. mmm. w m+ • »*.«_* m. %r _* M-,4_l_/' • A aooD deal of interest has been aroused by the recent announcement of tho appearance of a new Btar. Whoa one comes to think of it, it is a wonder that astronomers should have mapped oat the firmament so exactly that a single new star of no great magnitude should be noticeable, for though only some three thousand Btars are visible to tbe naked eye at one moment, powerful telescopes reveal about two hundrod millions. Only some twenty now stars have appeared during our astronomical history. Of course many thousands of stars not previously known to exist have been discovered by means of modern astronomical instruments. But this is not an old star now first revealed, but a newly-made star appearing in the constellation of Auriga, in tho Milky Way— a part of the heavens of which accurate charts exist. Tbe distance of the new star from tho earth is so great, however, that though its light has just reached tbe earth tho change it indicates in space may have taken place thirty or more years ago. Various theories as to the formation of new stars have been put forward from time to time. The older astronomers believed that they wero formed by tbe sudden condensation or agglomeration of nebulous material in tbe Milky Way. Sir Isaac Newton snggested that non-luminous stars suddenly became luminous through contaot with a comet. I Zollner at a lator period believed that I at certain periods of their formation stars I

"' i I i, ii 1 111,, .iHM, i..,.i.^—___-m l-li " Were covered with an opaque, non- lumin- I Ous crust, surrounding an fccanfleaient material, and that the bursting out of the interior produced beat aud light. The Speaker, in an interesting artiole on the new. star, tells us that) by means of tbe sf ectrosoope much more is now known on the subject, and although it oannot be said to be absolutely prove'd.'Lockyer's theory is generally acoepted by astronomers'. According to this theory new stars are formed out of masses oi meteorites or meteoric dust, each particle moving independently, but so far separated from the others that few collisions would be probable. Owißg to their mutual attraction, they would in time be drawn into a more compact mass, ia which more collisions among themselves would be certain to take place : these collisions would at first produce very feeble luminosity and heat, but, as their number increased, the temperature would be raised and vapour from the stones would be given off, so that a time would come when not a jingle stone would be left. Just before arriving alt this stage the star wonld be hottest^ and therefore brightest. After this it would begin to lower itoternperature—tha cooling would of coarse commence ffofn the outside, so that, aa the heat was radiated into space, the external surface would gradually become denser and resemble the sifrfatfa or photosphere of tbe sun as seen today. After - long lapse of time this external envelope would 6on« dense into c. liquid, and eventually into a solid mass, while the centre would still be at a high temperature —the condition of our earth at present. The Speaker thus explains the working of this theory : — " Space, _as we know, is not a vacuum, but contains this meteorio dust in sheets and streams, the particles composing which are moving in various directions with greater or less velocities. Let us imagine a olond of these stones all making their way through space ; it is Cleat that as they pursue their course they may meet occasionally with some of these meteorites, which will Oause collisions among the bodies composing the two swarms, Tho mass, aa a whole, would be more or less invisible so long as the collisions were small in number ; but suppose a denser swarm to suddenly meet another, like itself In rapid movement, what will be the result of these two opposing forces? The partloles In each swarm Would collide violently with thoso in the other j both heat and light wodld suddenly be emitted, and many meteorites would become incandescent add give off vapour. Aa tho swarms passed out from one another the collisions would be fewer, and so ths temperature would decrease ; and it would generally decrease quickly, for wo are dealing only with a number of small masses, and not with one large mass by itself. The word ' levelcrossing' has been used to denote the , intersection of these meteor Bwarms, and some Very flood instances o! them oan be perceived in photographs of the Pleiadies taken by Mr Roberts. From these photographs it can be gathered that the principal stars are not stars at all in the ordinary sense, but simply so many regions In a uobnla where the duststreams are intersecting." All new stars discovered iv our astronomical history have appeared in the Milky Way. This beftrs out Mr Lockyer's theory,' for the Milky Way is fall of oieteoric material and streams, affording just the conditions which would produce new stars under tho I hypothesis quoted above.