CHAPTER 16
Type II Supernovae
The derivation of the principal characteristics of objects moving at ultra high speeds in the preceding chapter gives us a foundation on which we can construct a theoretical picture of the nature and properties of astronomical objects of this class. Before so doing, however, it will be appropriate to give some attention to the process by which the ultra high speeds are generated.
As explained in Volume II, the continued existence of matter is subject to two limits, one related to the temperature, and therefore to the mass of the star in which the matter is located, and the other related to the age of the matter itself, subject to some modification by reason of its location We have seen that when the temperature limit is reached in the center of a star, that star explodes in an event known as a Type I supernova. Arrival at the age limit results in a similar explosion, which is called a Type II supernova. While these explosions are basically alike, in that each results from the sudden conversion of a substantial portion of the mass of the star into energy, and each produces some products that move with speeds greater than that of light, as well as slow moving products, there are also some significant differences that we will want to explore.
The upper destructive limit of matter is actually a limiting value of the magnetic ionization, but this is a function of age, because the magnetic ionization level continually increases under normal conditions. This ionization is equalized when atoms come into effective contact All components of a solid aggregate are therefore at the same ionization level. In the fluid states—liquid, gas, and condensed gas—the equalization process proceeds more slowly. Where the material aggregate is as large as a star, and there is a substantial inflow of matter from the environment, an ionization gradient is produced, extending from the lower level of the accreted material to the higher level of the older matter in the interior. When the ionization level in the interior reaches the destructive limit, and the explosion occurs, the matter that is still below the destructive ionization level is dispersed in space and in time in a manner similar to the dispersion of the products of the Type I supernova.
Reliable information about supernovae is very limited. Unfortunately, observations of the individual explosive events can only be made under some rather severe handicaps. No supernova has been observed in our galaxy for nearly 400 years, and information about the active stage of these objects can be obtained only from extragalactic observation, aside from such deductions as can be made from imprecise eyewitness accounts by observers of the supernovae of 1604 and earlier. The most meaningful information comes from examination of certain astronomical objects, a few of which are known to be remnants of old supernovae, and others that are similar enough to justify including them in the same category. Even at best, however, hard evidence is scarce, and it is not surprising that there is considerable difference of opinion among the astronomers as to classification and other issues. As might be expected under these circumstances, our deductions from physical theory conflict with some current astronomical thought.
The Type I explosion, according to our findings, originates in a star that has reached the size and temperature limits. This is a hot, massive star at the upper end of the main sequence, a member of a group of practically identical objects. Thus our theoretical conclusion is that all Type I supernovae are very much alike. The observers concede the validity of this conclusion. Here are some typical comments:
Type I supernovae display a fascinating homogeneity of photometric and spectroscopic properties.170 (David Branch)
Supernovae of Type I form a fairly homogenous group with relatively little variation between the spectrum of one star and that of the next… Supernovae of Type II constitute a much less homogenous group than those of Type I.31 (Robert P. Kirshner)
The supernovae other than those of Type I are actually so diverse that serious consideration has been given to defining several additional types. In the light of our findings it is apparent that a substantial degree of variation in the Type II events can be expected by reason of the differences in the masses of the exploding stars, and in their physical condition; that is, in the stage of the evolutionary cycle in which they happen to be at the time when they arrive at their age limits. Some of the observations show indications of mass differences. For instance, R. Minkowski reports that “The supernova of 1961 in NGC 4303 which Zwicky designates as Type III, shows properties that suggest strongly a supernova of Type II with unusually large ejected mass.”171 Massive objects are, of course, relatively rare in a sample drawn at random from the general run of stars, the great majority of which are small.
The astronomers have not been able to find a satisfactory explanation for the difference between the two classes of supernovae. Shklovsky, for instance, points out that this is one of the things that a theory of stellar explosions should explain:
Why, for instance, are the light curves of Type I supernovae so similar to one another? And why are the light curves of Type II supernovae so diverse?“ Theoreticians have found these questions very difficult indeed.172
The principal roadblock in the way of arriving at an answer to these questions is the prevailing commitment to the upside down evolutionary sequence, which is the basis for the current belief in astronomical circles that the Type II explosions are the ones that originate from the hot massive stars. Again quoting Shklovsky:
As for the stars that become Type II supernovae, it is logical to infer that they are young objects. This conclusion follows from the simple fact that they are located in spiral arms, where stars are formed out of a gas-dust medium.173
The lack of force in this argument can be appreciated if it is recalled that this same author characterized the current theory of star formation as “pure speculation.” This is another of the places where the uncritical acceptance of the physicists’ assumption as to the nature of the stellar energy generation process has diverted the astronomers’ thinking into the wrong channels, and induced them to close their eyes to the direct astronomical evidence. When the correct age sequence is recognized, all of the observations fall into line without difficulty.
Type I supernovae are found to be distributed among all of the various kinds of galaxies. This is consistent with our findings, as the limiting mass may theoretically be reached early in the life of a star, under appropriate circumstances. Age, on the other hand, is inconsistent with an early type of galaxy (with the usual exception that some old stray stars may be picked up by a young galaxy). A Type I event, if it occurs at all, must precede the Type II event that marks the demise of the star. Since the Type II supernova is a result of age, the explosions of this type are primarily phenomena of the older galaxies. The absence (or near absence) of Type II supernovae from the Magellanic clouds, for instance, is easily understood on the age basis, as these Clouds are clearly much younger than the Galaxy, according to the criteria that we have developed. On the other hand, this is a distinct embarrassment for the prevailing “massive star” theory of Type II supernovae. As explained by Shklovsky,
The fact that only Type I supernovae appear in irregular galaxies such as the Magellanic Clouds would seem inconsistent with the picture we have outlined, for these galaxies contain a great many hot, massive stars. Why is it that Type II supernovae are not observed there?173
What needs to be recognized is that when the observed facts are “inconsistent with the picture,” then they are telling us that the picture is wrong. This is the same message that we get from a whole assortment of astronomical observations that were discussed item by item in the preceding pages of this volume. All agree that the objects—stars, clusters, galaxies—characterized by astronomers as the older members of their respective classes are, in fact, the younger. This is to answer the Shklovsky’s question, and to a wide range of similar problems.
In spite of the absence of observed events, Type II supernovae are not totally excluded from small elliptical or irregular galaxies, or even from globular clusters. As pointed out earlier, all of these aggregates contain a few old stars that have been picked up from the environment during the formation and subsequent travel of the aggregates. When these old stars reach their age limits, supernova explosions take place. The absence of observed events of this kind is due to their scarcity. The Large Magellanic Cloud does contain a few supernova remnants that can be identified with Type II events, indicating that at least a few Type II supernovae have occurred in this galaxy within the last 100,000 years.
The observed Type II events are largely in the arms of the spiral galaxies, as indicated in one of the quotations from Shklovsky, but we find from theory that the great majority of the Type II supernovae occur in the unobservable inner regions of the giant spheroidal galaxies and the largest spirals. This is where the oldest stars are concentrated. The number of stars that undergo Type II explosions is considerably greater than the number that undergo Type I explosions, since all must eventually meet the Type II fate. This is offset in part by the fact that many stars repeat the Type I explosion at least once, in some cases several times. Aside from occurring much later in the life span of the star—at the very end—the most distinctive feature of the Type II explosion is that the intensity of the explosion, relative to the stellar mass, is much greater than in Type I. The total mass participating in the explosion is, in most cases, less than that of the massive star that becomes a Type I supernova, as the mass of the star involved in the Type II event may be anywhere between the maximum and minimum stellar limits. But the Type II explosion converts a much larger proportion of this mass into energy, and the ratio of energy to unconverted mass is therefore considerably higher, increasing the proportion of the mass going into the products with upper range speeds, and the maximum explosion speed of these products.
The optical emission from the explosion products comes mainly from the low speed component, the material that is expanding outward into space. Since the amount of this material is much smaller in the Type II events than in those of Type I, the optical magnitude of the Type II supernova at the peak is considerably less than that of the Type I events. One investigation arrived at average magnitudes of -18.6 for Type I and -16.5 for Type II.174 The emission from Type II also drops off more rapidly at first than that from Type I, and the light curves of the two types of explosions are thus quite different. This is one of the major criteria by which the observational distinction between the two types is drawn.
In view of the limited optical activity and the relatively small mass of the remnants, there has been some question as to what happened to the energy of these Type II events. Poveda and Woltjer, for instance, comment that they find it difficult to reconcile current ideas as to the energy release in the Type II supernovae with the present state of the remnants.175 This question is answered by our finding that the great bulk of the energy that is generated goes into the upper range explosion products, most of which are not optically visible.
These products include some that are moving at intermediate speeds, and are unobservable because their radiation is widely dispersed by the motion in time, and others moving at ultra high speeds and therefore optically visible only during the linear stage of their expansion. The ultra high-speed matter moves outward with the low speed products during this early stage. The intermediate speed matter has no spatial motion component of its own, but much of it is entrained with the outward-moving products. As a result this outward-moving cloud of matter contains local aggregates in which there are substantial amounts of material with the speeds and other characteristics of the white dwarf stars.
The long-continued radio emission of the remnants of the Type II supernovae is due to the presence of these upper range products. It was noted in Chapter 6 that the early white dwarf product of the Type I supernova is not visible optically, and manifests itself only by its radio emission. The same is true of the local concentrations of intermediate speed matter in the remnants, which are the equivalent of small-scale white dwarfs, and pass through the same evolutionary stages. Because of their small size, their evolution proceeds more rapidly, and even in the relatively short time during which the remnants are observable there are portions of the intermediate speed matter in all stages, including small aggregates with the outer shell of condensed gas that is characteristic of the white dwarfs in the visible stages. Thus the radiation from the remnants is not limited to dissipation of the kinetic energy imparted to the explosion products by the supernova. There is a continued generation of energy within the remnants. As the observers concede, the brightness of the supernova remnants decreases much less rapidly with increase in radius than conventional theory predicts.176 The supplemental energy generation is the answer to this problem.
Continued generation of energy in the remnants is manifested not only by the persistence of the radio emission, but also by direct evidence of energetic events within these structures. Inasmuch as conventional astronomical theory provides no means of generating energy in the explosion products, the prevailing view is that any emission of energy exceeding that, which can be ascribed to the initial explosion, must be introduced into the remnant from some separate source. In the case of the Crab Nebula, the remnant of a supernova observed in 1054 A.D., it has been estimated that an input of energy “of the order 1038 erg/see” is required to maintain the observed emission.177 The current belief is that this energy is derived from a dwarf star located in the center of the nebula, but this is purely hypothetical, and it depends on the existence of a transfer mechanism of which there is no evidence, or even a plausible theory.
The explanation that we derive from the theory of the universe of motion is that the continued supply of energy is due to radioactivity in the local concentrations of upper range matter in the remnants. It is the existence of this secondary energy generation in the Type II remnants that accounts for the great difference between the maximum period of observable radio emission in the Type I remnants, perhaps 3000 years, and that of the Type II remnants, which is estimated at more than 100,000 years. As an example of this difference, there is a nebulosity in the constellation Cygnus, known as the Cygnus Loop, which is generally considered to be a remnant of a Type II supernova, and is estimated to be about 60,000 years old. After all of this very long time has elapsed, we are still receiving almost twice as much radiation at 400 MHz (in the radio range) from this remnant as from all three of the historical (1006, 1572, and 1604) Type I supernova remnants combined.178
There are a number of other remnants with radio emissions that are far above the magnitudes that can be correlated with Type I. Also there are some remnants whose radio emission is within the range of the Type I products, but whose physical condition indicates an age far beyond the Type I limit. These must also be assigned to Type II. In general, it is probably safe to say that unless there is some evidence of comparatively recent origin, all remnants with substantial radio emission can be identified with Type II supernovae, even though Type I events may be more frequent in the observable region of our galaxy.
The conclusions as to the relative magnitude of the radio emission enable us to classify the most conspicuous of the remnants, the Crab Nebula, as a Type II product. The radio flux from this remnant is about 50 times that of the remnant of the Type I supernova that appeared in 1006, and is therefore of practically the same age. The Crab Nebula was originally assigned to Type I by the astronomers, mainly on the basis of the differences between it and Cassiopeia A, the remnant of a supernova that occurred about 1670 A.D., which was regarded as the prototype of the Type II remnant. More recently it has been recognized that the differences between the Crab Nebula and the Type I remnants are more significant. Minkowski, for instance, reports that “an unbiased assessment of the evidence leads to the conclusion that the Crab Nebula is not a remnant of a supernova of Type I.”171
This nebula consists of two physically distinct components, “one is an amorphous distribution of gas… and the other is a chaotic network of filaments.”179 In the center of the nebula there is a dwarf star of the Type II class, the nature and characteristics of which will be discussed in the next chapter. The presence of a star of this type definitely identifies the nebula as a product of a Type II supernova large enough to produce maximum speeds in the ultra high range.
On the basis of the theoretical considerations discussed in the preceding chapter, the presence of ultra high speed matter in the inward-moving product of the Type II supernova implies the existence of an observable outward-moving ultra high speed component, which should consist of one or more jets of material. Instead, as indicated above, the observers report the presence of a “chaotic network of filaments.” So let us take a look at the nature of these filaments.
The dictionaries define the word “filament” as a “slender, threadlike object.” We are accustomed to the way in which astronomical magnitudes dwarf those of our ordinary experience. Indeed, we commonly use the term “astronomical” in the sense of “extremely large.” But even so, it comes as somewhat of a shock when we are told that “on the average the bright filaments are 1.4 arc sec. in diameter, which corresponds to a width of 2.5×1012 km.180 The “slender” object is more than a hundred billion kilometers in diameter. But this does give us an answer to the question as to the nature of the filaments. These “slender” filaments are clearly the same kind of entities that we call jets in a different context. Their erratic courses are undoubtedly due to the resistance that they meet as they make their way through the clouds of matter moving at lower speeds.
There is also a problem in connection with the so-called “amorphous” component of the nebula. It must consist in part of the low speed products of the supernova explosion, but the properties of this component do not resemble those of a hot gas and dust mixture. In fact, even though it is identified as a “gas,” its spectrum is continuous, like that of a solid. This seeming anomaly gives us the clue that points the way to an explanation of the observations. An explosion that is powerful enough to give some of its products speeds in the ultra high range also accelerates other portions of its products to speeds just below the ultra high level; that is, the upper part of the intermediate range. These intermediate products are moving in time only, and have no capability of independent motion in space, but most of them are entrained in the moving components. Those that mix with the low speed matter are carried along until the particles individually drop out of the stream. This settling out process begins immediately after ejection. The outward motion of the products of the Crab supernova has therefore left the volume of the nebula filled with scattered particles of intermediate speed matter concentrated toward the center,181 rather than toward the periphery, as in the shell structures that are typical of supernova remnants in general.
As we saw in our examination of the theoretical aspects of the upper range speeds in the preceding chapter, particles moving with speeds in the upper portion of the intermediate speed range radiate in the same manner as those in the lower portion of the range below unity; that is, with a continuous spectrum. The physical state of this material is the temporal equivalent of the solid state: a condition in which the atoms occupy fixed positions in three-dimensional time, and the emission is modified in the same manner as in the solid state. Here we have another concept that is totally foreign to conventional physical thought. For that reason it will undoubtedly be difficult for many persons to accept. But it is clearly the kind of a result that necessarily follows from the general reciprocal relation between space and time. The two speed ranges with continuum emission are symmetrically related with respect to the natural datum level: unit speed. Furthermore, the intermediate range continuum radiation is not limited to supernova remnants. We will meet the same kind of radiation from matter in the same temperature range later, under different circumstances.
The theoretical presentation in Chapter 15 also explains why the filaments, which are in a still higher speed range, have a line spectrum. As brought out there, motion in a second scalar dimension is incapable of representation in the conventional spatial reference system, but the elimination of the gravitational effect by this motion does cause an observable change of position in that system. This indirect result applies to the thermal motion as well as to the unidirectional translational motion previously considered, but in both cases the magnitude of the observed motion is subject to the limitations on the gravitational speed in one dimension; that is, it is confined to the range below unity. Thus, even though the speeds of the particles in the filaments are in the ultra high range, the observable thermal effect is in the low speed range, and the radiation that is produced has a line spectrum like that of an ordinary hot gas.
It has not been possible to extend the present investigation to an analysis of the spectra of astronomical objects because of the amount of time that would be required for such an undertaking. Some aspects of these spectra that are of special significance in connection with the subjects under discussion will, however, be noted briefly as we proceed. In the case of the Crab Nebula much stress has been laid by the astronomers on two points: (1) that the radiation is non-thermal, and (2) that it is polarized. It will therefore be appropriate to point out that, according to our theoretical findings: (1) all radiation from objects with upper range speeds, except that generated by indirect processes such as the one explained in the preceding paragraph, is non-thermal, and (2) all such radiation is polarized as emitted. Where a lower polarization is observed, this is due to depolarizing effects during travel of the radiation. A three-dimensional distribution of radiation is impossible in a two-dimensional region.
As noted earlier, the observed characteristics of Cassiopeia A, the other very conspicuous (at radio frequencies) supernova remnant, are quite different from those of the Crab Nebula, even though it is now conceded (not without dissent) that both are Type II remnants. Here again, there are two components of the remnant, but neither resembles a component of the Crab Nebula. Both appear to consist mainly of local concentrations of ordinary matter distributed in the volume of space occupied by the remnant. The objects of one class are moving rapidly, and are located mainly at the periphery of the remnant in what is commonly described as a shell. The other objects are larger, more evenly distributed throughout the remnant, and nearly stationary. The shell is no doubt composed of the outward-moving low speed explosion products. The problem of accounting for the quasi-stationary objects in the context of conventional astronomical theory has been very difficult; so difficult, in fact, that there is a tendency to try to dodge the whole issue, as in the following statement:
The only possible interpretation of the stationary filaments in Cas A is that these filaments were present before the supernova outburst.182
Here again we meet the assumption of omniscience that is so curiously prevalent among the investigators of the least known areas of science. From the very start of the investigation whose results are being reported in this work, the answers to outstanding problems have almost invariably been found in areas in which the adherents of orthodox theories have claimed that they have examined all conceivable alternatives. The Cassiopeia A situation is no exception. The explanation that these authors characterize as impossible can be obtained from a consideration of the theory that is being discussed in this work.
There is no indication of the existence of a Type II dwarf in the remnant. We can conclude from its absence that the Cassiopeia A supernova was not energetic enough to produce significant amounts of ultra high-speed products. On this basis, the two components of the remnant can be identified as low speed and intermediate speed products This raises another issue, because intermediate speeds in the dense central core of an exploding star would normally cause inward motion and production of a Type I dwarf. No such product is observed. From its absence we can conclude that the star of which Cassiopeia A is a remnant did not have a dense core; that is, it was a star of the giant, or pre-giant, class, in an early stage before there was much central condensation. The Type II explosion can take place at any stage of the stellar cycle. If it happens during a diffuse stage, the explosion involves the entire structure the explosion forces are predominantly outward, and they are distributed so widely that they d`, not reach the ultra high levels. In this case the intermediate speed products are entrained in the outgoing low speed matter, and are distributed in the remnant in much the same manner as the amorphous mass in the Crab Nebula, but in local concentrations because of the lower density of the moving matter in which they are being carried.
Explosion of a relatively cool and extremely diffuse star would not be as spectacular an event as an ordinary supernova. This is probably the reason, or at least a major part of the reason, why there is no record of an observation of the supernova that produced Cassiopeia A. The explanation of the strength of the radiation now being received from this remnant, and the rather rapid decrease in the amount of this radiation, will become apparent when the process by which the radiation is generated is described in Chapter 18.
From the explanations that have been given, it can be seen that the unique characteristics of both Cassiopeia A and the Crab Nebula are due to the youth of these objects. These are features of the very early post-explosion stages. Within a few thousand years these early phases of the evolutionary development will be completed. The optically observable activity in the remnant will then be confined almost entirely to the outer shell, where the outward-moving low speed component is concentrated. Radio and x-ray emission will continue on a reduced scale for a considerable period of time. The Vela remnant, estimated to be about l0,000 years old, has already reached this more advanced age.