V.5 No 1

15

Chapter 2. Hypothesis of origin of planetary system (part I1)

We see the calculations having too much discrepancies, the phenomenology to be able to explain them. We see straight necessity, some new hypotheses to be able to interrelate the thermonuclear evolution of star with its explosions. Too artificial relation, as before any numerical estimations, they would have to prove this connection phenomenologically. It remains to add, just in the early 20th century, in the envelope of 'supernova' of 1006 the scientists revealed the lines of strongly ionised iron; as these lines were much unexpected, the death (as they thought) of that star was suspected to be caused namely by the fact that it has achieved the iron stage. Factually, the hypotheses of that period proceeded from the before-given condition that the iron stage is fatal for a star. Perhaps in the heat of study they somehow forgot, this supposition has no grounds - and the whole construction can appear bankrupt, if this were not corroborated.

[1, p. 275], in which about 1 Mev is released.

There exist some more exotic and less grounded attempts to explain the process; we will not consider them.

There exists an attempt by V.S. Imshennik and D.K. Nadezhdin to provide a quantitative estimation of shock wave coming from the centre of exploding star, whatever would be the cause of explosion. But its utmost estimation appear by several orders weaker than the observed scale of stellar explosions [1, p. 273- 274]. And again, this theory tells nothing about the cause of phenomenon.

And the main, theories of this number are fragmentary and consider not so much the explosion as collapse - the process with the opposite sign of force direction. The scientists never succeeded to explain just the cause of explosions. Consequently, the explanation for whose sake these suppositions are advanced has to be another.

Special place in the row of collapse theories takes Schwarzschild theory. It predicts that if during its gravitational contraction the star achieved some limit (so-called Schwarzschild sphere), there will happen an irreversible collapse and the star will turn into a 'black hole'. From this the followers concluded that not only nuclear but also gravity forces can appear the cause of explosion. In [14] we proved theories of this row ungrounded, 'black holes' are basically impossible by the reasons stated in that paper.

An indisputable conclusion follows from this all: theories of stellar collapse are artificial and ungrounded; and theories of intermittent, 'tossing' chemical evolution of stars.

At the same time Shklovsky himself emphasises an important detail: "there exist the stars with anomalously high abundance of carbon, or sometimes there are found astonishing features with anomalously high abundance of rare earths. If overwhelming majority of stars have absolutely negligible abundance of lithium (~ 10^-11 from that of hydrogen), there seldom are found the 'unique' objects where this rare element is quite abundant … There are stars in whose spectra were revealed the lines of not existent on the Earth 'in its natural state' element technetium" [1, p. 18]. Below, when considering stellar wind and magnetic stars, we will give another citation telling that in the adult stars, heavy elements exist and are quite abundant, up to the rare earths. These are the observational data.

There arise two questions: first, we to see so heavy elements (atomic weight of technetium is 98, and of promethium also found in spectra - 145) having come to the surface in so abundant amount that are well indicated in the far, in the nucleus there have to be present much heavier elements. And second, we know on the Earth elements with the atomic weight even more than 230. Would we fancy that they have been synthesised in the depths of our planet? But then, where have they been synthesised, if not in the star that gave an origin to the planets of our system? And in meteorites, "products of decomposition of short-living radioactive nuclides (²⁶Al, ¹⁰⁴Pd, ²⁰²Pb, ²⁴⁷Cm and others)" [28, p. 485] have been found as typical, which also had no place where to be produced, except in the star nucleus. It appears, we have to premise both stirring substance in the depths (or heavy elements would be unable to come to the surface) and much more advanced synthesis, doing not interrupting it by an explosion or collapse just at the stage of iron. The more that physical conditions in each star are individual, due to which the substance decomposition 'without fail after the iron stage' seems some doubtful. And on the other hand, we are not aware, whether there is and which the limit of substance state at 810⁹ K. Rather, even at usual terrestrial pressure the limit would happen earlier; the pressure of depths introduces its correction, - and again, each star has its own pressure. And nothing is new in this reasoning; Yaroshevsky just so explains the samarium in meteorites as produced "at the last stage of nucleosynthesis 100- 200 million years before the solid phase was formed in the Solar system" [28, p. 485]. With all doubt as to his numerical estimation, the very premise seems to be logic and natural.

Let us try to take into account one more aspect of nuclear processes - namely that atoms and nuclei are discrete systems and each such system reacts to the external affection independently. Given this,

1. The pressure exceeds the potential barrier simultaneously for all atoms being at equal conditions in the centre of protostar, and this simultaneity causes the flare. But this is a negligibly small part of total mass of a star.

2. When some particular pair of protons joins, new nucleus takes less space than two atoms of this sum took before. This micro-collapse for a while throws off the pressure in the near of new nucleus and slightly slows down the process at this micro-vicinity, but the pressure is quickly equalised by the pressure of surrounding atoms; as the result, in the nucleosynthesis at each macro-level the substance is continuously compacted.

3. Alike, there hardly exists a clear boundary in synthesis of double, triple etc. associations. Rather, this is determined by local conditions at each level and even at each particular point of the system, as well as by individual potential barrier of each proton and of association. Consequently, we may not strongly divide the stages of synthesis of double, triple etc. systems but should rather speak of smooth increase of associations and of processes that mainly go at some or other stage of star evolution.

4. It follows from the said that the energy releasing in the synthesis of each separate nucleus continuously increases the temperature (and, accordingly, pressure) in the depths, and at the macro-level it continuously causes the conditions for further complication of nucleus.

5. Should only the gravity force controlled substance distribution in the star, then, by virtue of gravitational differentiation of substance, new heavier atoms that are synthesised in the nucleus would never leave the star's centre, and we would never see on its surface any other elements than those lightest. When in the star's centre the stock of hydrogen is exhausted, thermonuclear synthesis would stop already at the first or second stage, and stars would never come to their known appearance. Just the fact that synthesis continues tells that the mixing force exists - this obviously has to be thermal convection and centrifugal force of rotation adding to that thermal.

All said in the items 1- 5 tells of continuous and smooth but in no case of zigzag-like and interrupted progress of the nucleosynthesis. Accordingly, the idea of intermittent evolution and all numerical characteristics of Shklovsky's zigzag-like diagram abolish themselves. Although further, at the stage of pulsar, we will see some stages, it will have no relation to interruption in evolution either to change of the sign of process but will have absolutely other cause, and we will explain it further.

As a corollary of such view, it would be appropriate to see as an example, why atmospheres of some stars - for instance, of Taurus T whose distinction is stormy convection - are so rich of beryllium, boron and lithium; as Shklovsky writes [1, p. 100], these elements are there hundreds times more abundant than in the atmosphere of Sun. Such stars are now at the stage of evolution at which these elements already have been displaced from depths to the envelope of star as lightest; this tells, in the depths much heavier elements are synthesised; but at the same time the number of heavy elements in these stars is not plenty, and mentioned elements still are considerably noted among background.

We would also underline that pressure in the nucleus corresponds to the condition of stability of any elements which it produces. Heavy nuclei for whose stable existence the conditions are insufficient simply will not produce, and there is no obvious reason to suppose nucleus decomposition, having not stipulated the fall of pressure. If in convective mix the substance came onto the surface, it will decompose or not, dependently on conditions on the surface. Therefore, not iron, samarium, californium or any other calculated element is the limit of thermonuclear progress, but only stellar mass able to densify to such or other pressure utmost for this star and to provide the synthesis of such or other element. Up to this limit, the synthesis grows continuously, then 'the boiler' some time works stable, until in the very centre there appeared finished the synthesis of all associations that are maximally possible under given temperature and pressure which the given stellar mass is able to provide; then the star begins decaying. (As we mentioned, in this item we describe only an ideal course of process. Possible variants of instability will be considered below).

To illustrate the general pattern of chemical evolution of outer, observable layers of stars, we will cite the conventional Harvard spectral classification of stars:

"About 90% of stellar spectra are included to one of below classes, and a gradual transition exists between them.

Class O. Typical lines of singly ionised helium, twice ionised oxygen. No lines of metals. Continuous background propagates far into ultraviolet range. …

Class B. Helium line. Weak hydrogen lines. Dotted H and K lines of ionised calcium.

Class A. Hydrogen lines are most intensive. Weak H and K lines of ionised calcium and other metals.

Class F. Hydrogen lines weaken, H and K lines of ionised calcium and metals become stronger. G-stripe of hydrocarbon appears.

Class G. Fully developed lines of metals. Most intensive lines of calcium.

Class K. Calcium lines are still strong, but definitive in the spectrum are lines of metals, G-stripe is intensive. Lilac end of continuous spectrum is well weaker.

Class M. Lines of metals are visible but weak. Absorption stripes of titan oxide and other molecular compounds are intensive. G-stripe weakens. Very weak lilac end of continuous spectrum.

Classes R, N, C are branching from K-class; not much number of cold stars whose temperature is lower than 3000^? relate to them; for their spectra are typical the absorption stripes of molecules of carbon, cyan, oxides of titanium and zirconium" [29, p. 58].

As we see, the evolution can be followed continuously, and after commonly observed appearance and evolution of metal lines we see the same regular production of their compounds, which corresponds to lower surface temperature.

It will be appropriate to add here, just in stars of S-class there are seen the lines of rare earths and technetium of which Shklovsky writes that their presence can be explained only by thermonuclear reactions going there on the surface [1, p. 135]. But in the stellar classifier we see, stars of this class have very cold, lower than 3000^o temperature of surface, which is inappropriate for thermonuclear reactions, especially under condition of small pressure on the 'surface' of star. Shklovsky also supposes that more or less complex atoms can be produced only in the shock wave in the envelopes of 'supernovae' just in the course of explosion and that heavy (transuranium) elements were produced in the very first, most powerful explosions in the universe [1, p. 264]; presently their production is already impossible, so Shklovsky means them to be relicts and rarity of the universe. Actually, some version is necessary, if we in our calculations exclude the possibility, heavy elements to be produced straight in the nucleosynthesis in the star centre. But it would be not out of place to note: in the explosion, gas of envelope impetuously expands and cools, so thermonuclear reactions basically cannot go there. Rather, in the 'universal egg' there would exist some single 'universal atom'; when substance scattered, it would decompose to some quite heavy atomic weights - to the limit at which the 'protons' of its super-nucleus would stop impose on each other the superfluous pressure, so we would have now monatomic celestial bodies. We see nothing of the kind in all the nature. Thus, Shklovsky's version cannot explain the origin of heavy elements.

While we in our reasoning showed, substance in the star is permanently mixed and nucleosynthesis goes quite long time; it continuously progresses and produces atomic nuclei of such weight as the mass of this star can provide. This means, the limit of complication is very individual for each star, the same as its mass. Thereupon, heavy elements are produced in the star nuclei in a regular way, and to the S-stage of evolution, old stars have in their depths such stock of much heavier elements that rare earths are already ousted to the convective layers as lighter elements.

But if the nucleosynthesis was continuous, the cause of bursts sought in the nuclear chemistry of processes is not there. We have to seek it in still disregarded physical features of process. Now let us consider them.