03 Globular Clusters

CHAPTER 3

Globular Clusters

In the preceding chapter we saw that galaxies (small ones, called globular clusters) condense out of diffuse material, grow by accretion and capture, and finally at an advanced age reach the limiting size, that of a giant spheroidal galaxy. This is the essence of the large-scale evolutionary process in the material sector of the universe, the subject of the first half of this volume. The next several chapters will be devoted to examining the most significant details of this process. We will first turn our attention to the galaxies, junior grade, the globular clusters.

It should be noted, in this connection, that current astronomical theory has no explanation for either the formation of the clusters or their existence in their present form. It is generally assumed that the clusters are products of the process of galaxy formation, but this provides no answer to the problem, in view of the absence of anything more than vague and tentative ideas as to how the galaxies were formed.

The clusters are spherical, or nearly spherical, aggregates containing from about 20,000 stars to a maximum that is subject to some difference of opinion, but is probably in the neighborhood of a million stars. These are contained in a space with a diameter of from about 5 to perhaps 25 parsecs. The parsec is a unit of distance equivalent to 3.26 light years. Both of these units are in common use m astronomy, and in order to conform to the language in which the information extracted from the astronomical literature is expressed, both units will be employed in the pages that follow.

The structure of these clusters has long been a mystery. The problem is that only one force of any significant magnitude that of gravitation has been definitely identified as operative in the clusters. Inasmuch as the gravitational force increases as the distance decreases, the force that is adequate to hold the cluster together should be more than adequate to draw the constituent stars together into one single mass, and why this does not happen has never been ascertained. Obviously some counter force is acting against gravitation, but the astronomers have been unable to find any such force. Orbital motion naturally suggests itself, in view of the prevalence of such motion among astronomical objects, but the rotations of the clusters, if they are rotating at all, are far too small to account for the outward force. For example, K. Cudworth, reporting on a study of M 13, says that ”no evidence of cluster rotation was found. It is recognized that this is a problem that calls for an answer. “Why then is the rotation of globular clusters so small?” ask Freeman and Norris. Those who dislike having to concede that there is a significant gap in astronomical knowledge here are inclined to make much of the fact that a few clusters do show some signs of rotation. For instance, Omega Centauri is slightly flattened, and some indication of rotation has been found in the spectra of M 3. But a showing that some clusters rotate is meaningless. All must be rotating quite rapidly to give any substance to the hypothesis that rotational forces are counterbalancing the gravitational attraction. If even one cluster is not rotating, or is rotating only slowly, this is sufficient to demonstrate that rotation is not the answer to the problem. Thus it is clear that rotation does not provide the required counter force.

The suggestion has also been made that these clusters may be similar to aggregates of gas molecules, in which the individual units maintain a wide separation, on the average. But such an explanation requires both high stellar speeds and frequent collisions, neither of which can be substantiated by observation. Furthermore, the existence of the gaseous type of structure depends on elastic collisions, and the impact of stars upon stars, if it were possible, would certainly not be elastic. Indeed a rather large degree of fragmentation could be expected. Together with the large kinetic energies that would be required to counterbalance the weight of the overlying layers of stars, this would result in a physical condition in the central regions of the clusters very different from that existing in the outlying regions. Here, again, no such effect is observed.

The astronomers are reluctant to concede that such a conspicuous problem as that of the structure of these clusters is without an acceptable solution, and the general tendency is to assume that the possibilities mentioned in the preceding paragraphs will somehow develop into an answer at some future time. It is therefore significant that exactly the same problem exists with respect to the observed dust and gas clouds in the Galaxy, and here, where the processes suggested as possible explanations of the cluster structure clearly do not apply, the theorists are forced to admit that this is “a major unanswered question.” The dust cloud situation will be discussed in Chapter 9.

As in so many of the phenomena previously examined, the answer to this problem is provided by the outward progression of the natural reference system relative to the conventional stationary system of reference. Because of the way in which the cluster is formed, every constituent star is outside the gravitational limits of its neighbors, and therefore has a net outward motion away from each of them. Coincidentally, all of the stars in the cluster are subject to a motion toward the center of the aggregate by reason of the gravitational effect of the cluster as a whole. Near this center, where the gravitational effect of the aggregate is at a minimum, the net motion is outward. But in the outer regions of the cluster, where the gravitational motion exceeds the progression of the reference system, the net motion is inward. The outer stars thus exert a force on the inner ones, confining them to a finite volume, in much the same way that the fabric of a balloon confines the gas that it encloses. The immense region of space around each star is thus reserved for that star alone, irrespective of the stellar motions. Whether or not the cluster acquires a rotation is immaterial. It is equally stable in a static condition.

This question as to the structure of the globular clusters is only one of many physical situations in which an equilibrium exists between gravitation and a hitherto unidentified counter force. Because of the lack of understanding of the nature and origin of this force, the general tendency has been to ignore it, and either to grope for some other kind of answers, as in the globular cluster case, or to evade the issue in some manner. One of the few authors who has recognized that an “antagonist” to gravitation must exist is Karl Darrow. “This essential and powerful force has no name of its own,” Darrow points out in an article published in 1942. ”This is because it is usually described in words not conveying directly the notion of force. By this means, Darrow says, the physicist “manages to avoid the question.” In spite of the clear exposition of the subject by Darrow (a distinguished member of the Scientific Establishment), and the continually growing number of cases in which the “antagonist” is clearly required in order to explain the existing relations, the physicists have “managed to avoid the question” for another forty years.

The development of the theory of a universe of motion has now revealed that the interaction between two oppositely directed forces plays a major role in many physical processes all the way from inter-atomic events to major astronomical phenomena. We will meet the “antagonist” to gravitation again and again in the pages that follow. Like gravitation, this counter force, which we have identified as the force due to the outward progression of the natural reference system relative to the conventional system of reference, is radial in the globular cluster, and since these two are the only forces that are operative to any significant degree during the formative period, the contraction of the original cloud of dust and gas into a cluster of stars is accomplished without introducing any appreciable amount of rotation. This is the answer to the question posed by Freeman and Norris. As noted in Chapter 2, consolidation of two or more of these clusters to form a small galaxy usually results in a rotating structure. The same result could be produced on a smaller scale if the cluster picks up a stray group of stars or a small dust cloud. Some such event, or gravitational effects during the approach to the Galaxy, probably accounts for the small amount of rotation that does exist in some clusters.

The compression of the cluster structure reduces the inter-stellar distances to some extent, but they are still immense. Current estimates put the density at the center of the cluster at about 50 stars per cubic parsec, as compared to one star per ten cubic parsecs in the solar vicinity.27 This corresponds to a reduction in separation by a factor of eight. Since the local separation exceeds 112 parsecs, or five light years, the average separation in the central regions after compression is still more than half of a light year, or 3×1012 miles, an enormous distance.

For general application to the inter-stellar distances, the term “star system” has to be substituted for the word “star” as used in the foregoing paragraphs, but star systems in this sense are rare in the globular clusters. The origin and nature of double and multiple systems will be discussed in Chapter 7.

In assessing the significance of the various available items of information about the globular clusters, to which we will now turn our attention, it should be kept in mind that all of the conclusions that have been reached in this work concerning these individual items are derived from the same source as the foregoing explanations of the origin and structure of the globular clusters; that is, from the postulates that define the universe of motion.

As indicated in the preceding chapter, the observations of the globular clusters add materially to the amount of evidence confirming the theoretical conclusions as to the growth of the galactic aggregates by the capture process. On the basis of this theory, each galaxy is pulling in all of the clusters within its gravitational limits. We can therefore expect all galaxies, except those that are still very young and very small, to be surrounded by a concentration of globular clusters moving gradually inward. Inasmuch as the original formation of the clusters took place practically uniformly throughout all of the space under the gravitational control of each galaxy (except for a very large-scale radial effect that will be discussed later), the concentration of clusters should theoretically continue to increase as the galaxy is approached, until the capture zone is reached. Furthermore, the number of clusters in the immediate vicinity of each galaxy should theoretically be a function of the gravitational force and the size of the region within the gravitational limit, both of which are related to the size of the galaxy.

These theoretical conclusions are confirmed by observation. A few clusters have been found accompanying such small galaxies as the member of the Local Group located in Fornax; there are several in the Small Magellanic Cloud and two dozen or more in the Large Cloud; our Milky Way galaxy has 150 to 200, when allowance is made for those which we cannot see for one reason or another; the Andromeda spiral, M 31, has the same or more; NGC 4594, the “Sombrero” galaxy, is reported to have “several hundred” associated clusters; while the number surrounding M 87 is estimated to be from one to two thousand.

These numbers of clusters are definitely in the same order as the galactic sizes indicated by observation and by criteria previously established. The Fornax—Small Cloud—Large Cloud—Milky Way sequence is not open to question. M 31 and our own galaxy are probably close to the same size, but there are indications that M 31 is slightly larger. The dominant nucleus in NGC 4594 shows that this galaxy is still older and larger, while all of the characteristics of M 87 suggest that it is near the upper limit of galactic size.

Observation gives us only what amounts to an instantaneous picture, and to support the validity of the theoretical deductions we must rely primarily on the fact that the positions of the clusters as observed are strictly in accord with the requirements of the theory. It is significant, however, that such information as is available about the motions of the clusters of our own galaxy is also entirely consistent with the theoretical findings. In the words of Struve, we know ”that the orbits of the clusters tend to be almost rectilinear, that they move much as freely falling bodies attracted by the galactic center. According to the theory of the universe of motion, this is just exactly what they are.

We see the globular clusters as a roughly spherical halo extending out to a distance of about 100,000 light years from the galactic center. There is no definite limit to this zone. The cluster concentration gradually decreases until it reaches the cluster density of intergalactic space, and individual clusters have been located out as far as 500,000 light years. This distribution of the clusters is completely in agreement with the theoretical conclusion that the clusters do not constitute parts of the galactic structure, but are independent units that are on the way to capture by the Galaxy. Both the spherical distribution and the greater concentration in the immediate vicinity of the Galaxy are purely geometrical consequences of the tact that the gravitational forces of the Galaxy are pulling the clusters in from all directions at a relatively constant rate.

On the basis of the theoretical findings described in the preceding pages, the globular clusters are the youngest of the visible astronomical structures, and the stars of which they are composed (aside from an occasional older star or a small group of stars obtained from the environment in which the cluster condensed) are the youngest members of the stellar population. One of the observable consequences of this youth is supplied by the composition of the matter in the cluster stars. Inasmuch as the build-up of the heavier elements, according to the theoretical findings, is a continuing process, offset only to a limited extent by the destruction of those atoms that reach one or the other of the destructive limits, the proportion of heavy elements in any aggregate increases with age. It can be expected, then, that the stars of the globular clusters, with only a few exceptions, are composed of relatively young matter, in which the heavy element content is low.

The evidence concerning the stellar composition is somewhat limited, as the observations reflect only the conditions in the outer regions of the stars, and are influenced to a substantial degree by the character of the material currently being accreted from the environment. “Detailed studies of the composition of stars,” says J. L. Greenstein, ”can he made only in their atmospheres. However, the differences in the reported values are too large to leave any doubt as to the general situation. For example, the percentage of elements above helium in the average globular cluster is reported to be lower by a factor of 10 or more than the corresponding percentage in the sun.

Current astronomical theory concedes that the matter in the stars of the globular clusters is matter of a less advanced type than that in the spiral arms, but to reconcile this fact with the prevailing ideas as to the age of the clusters it invokes the assumptions (1) that the heavier elements were produced in the stellar interiors, (2) that they were ejected therefrom in supernova explosions, and (3) that the stars with the greater heavy element content were formed from this ejected material. This is an ingenious theory, but it is being called upon to explain a situation that is decidedly abnormal. The normal expectation would, of course, be that the youngest matter would be found in the youngest structures. A theory that postulates a reversal of the normal relationships is not ordinarily given serious consideration unless some strong evidence in its favor can be produced, but in this case there is no observational evidence to support any of the three assumptions. Indeed, there is some evidence to the contrary, as in the following report:

The relative abundance of these [heavy] elements in the supernova is not very different from their abundance in the sun. If the supernovae synthesize heavy elements out of lighter ones in the course of their explosion, none of that material is initially seen in the rapidly expanding debris. (Robert P. Kirshner).

This is an example of the way in which, as noted in Chapter 1, the astronomical community is disregarding or distorting the evidence from observation in order to avoid contradicting the physicists conclusions as to the nature of the stellar energy generation process. The failure to find any evidence of the predicted increase in the concentration of heavy elements in the supernova products is, in itself, a serious blow to a theory that rests entirely on assumptions, but it is only one of a long list of similar conflicts and inconsistencies that we will encounter as we proceed with our examination of the astronomical field.

As will be demonstrated in the pages that follow, all of the relevant astronomical evidence that is available is consistent with the theoretical identification of the course of galactic evolution outlined in the preceding pages, and is more than ample to confirm its validity. In fact, the available data concerning the globular clusters are sufficient in themselves to provide a conclusive verification of the theoretical conclusions set forth in this work. The remainder of this chapter will review these globular cluster data, and will indicate their relevance to the point at issue. The various items of information that have been accumulated will be described briefly. Each description will then be followed by a short discussion, indicating the manner in which this item is related to the point that is being demonstrated: the validity of the new conclusions with respect to the place of the clusters in the evolutionary sequence.

  1. Observation: The globular cluster structure is stable.

    Comment: The explanation of the hitherto inexplicable structure of the clusters has already been discussed, but it should be included in the present review of the evidence contributed by the observations. The fact that the explanation of the cluster structure is provided by the existence of the same hitherto unrecognized factor that accounts for the recession of the distant galaxies is particularly significant.

  2. Observation: The proportion of heavy elements in the stars of the globular clusters is considerably lower than in the stars and interstellar material in the solar neighborhood.

    Comment: Like item number 1, this fact, already discussed, is being included in the list so that it will appear in the summary of the evidence.

  3. Observation: Some globular clusters contain appreciable numbers of hot stars.

    Comment: This observed fact is very disturbing to the supporters of current theories. Struve, for example, called the presence of hot stars an “apparent defiance” of stellar evolutionary theory. But it is entirely in harmony with the theory of the universe of motion. Some stars, or groups of stars, are separated from the various aggregates by explosive processes, and are scattered into intergalactic space. As the globular clusters form from dispersed material they incorporate any of these strays that happen to be present. Others are captured as the clusters move through space. The presence of a small component of older and hotter stars in some of the young globular clusters is thus normal in the universe of motion. On the other hand, if the clusters have always existed in the outer regions of the galaxies, and are composed of very old stars, in accordance with conventional astronomical theory, the hot stars (which in this theory are young) should have disappeared long ago.

  4. Observation: Some clusters also contain nebulous material.

    Comment: Helen S. Hogg, writing in the Encyclopedia Britannica, says, “Puzzling features in some globular clusters are dark lanes of nebulous material.” It is difficult, she says, ”to explain the presence of distinct, separate masses of unformed material in old systems. Quite true. But it is easy to explain the presence of such material in young systems, which the clusters are, according to the findings of this work.

  5. Observation: There is an increasing amount of evidence indicating that very large dust clouds are being pulled into the Galaxy.

    Comment: This observed phenomenon has not yet been fitted into conventional astronomical theory. It is part of the cannibalism that is contrary to the premises of that theory, but is not yet clearly recognized in that light. In the universe of motion, the significance of these incoming dust clouds is clear. They are simply unconsolidated globular clusters, aggregates that have been, or are about to be, captured by the Galaxy before they have had time to complete the process of star formation. Considerable information concerning the structure of these unconsolidated clusters, and the nature of the processes that they undergo after entering the Galaxy, is now available, and will be examined in Chapter 9.

  6. Observation: Aside from the somewhat exceptional instances where nebulous material is present, the globular clusters show little evidence of the presence of dust.

    Comment: Current astronomical theory ascribes this to age, assuming that over a long period of time the original dust will have been formed into stars, or captured by stars. Our finding is that the nature of the globular cluster condensation process results in almost all of the dust and gas of which the cluster was originally composed being brought under the gravitational control of the stars. In this condition the dust is not observable as a separate phenomenon. Evidence of the existence of dust aggregates is observed only where the normal condensation process has been subject to some disturbing influence, or where a dust cloud has been captured.

  7. Observation: Globular clusters exist in a zone surrounding our galaxy that extends out to a distance of at least 100,000 light years from the galactic center, and in similar locations around other galaxies. The existence of a substantial number of clusters in intergalactic space is also indicated.

    Comment: The crucial point in this connection is the number of intergalactic clusters. According to conventional theory, the formation of the Globular clusters was part of the formation of the galaxies, and there should be no clusters between the galaxies other than a few strays. In the universe of motion intergalactic space is the original zone of formation of the clusters, and the concentration around each galaxy is merely a geometric result of the gravitational notion toward the galaxy from all directions. On this basis there should be no definite limits to the cluster zone. The clusters should just thin out gradually until they reach the approximately uniform density in which they exist in space that is free of large aggregates of matter. The total number of’ intergalactic clusters should thus be very large The amount of information currently available is not sufficient to produce a definitive answer to the question as to how common these intergalactic clusters actually are, hut the increasing number of discoveries of distant clusters is highly favorable to the new theory.

    The growing realization that dwarf’ galaxies, not much larger than globular clusters, may he ’’the most common type of’ galaxy in the universe’’ is a significant step toward recognition that intergalactic space is well populated with globular clusters. Indeed, some of the aggregates that are now being identified as dwarf galaxies may actually be globular clusters. Current estimates of the size of these dwarf galaxies, which put the average at about one million stars, are within the range of the estimates of the sizes of the globular clusters that have been made by other observers.

  8. Observation: The number of clusters associated with each galaxy is a function of the mass of the galaxy.

    Comment: Either theory can produce a satisfactory explanation of this fact. On the basis of conventional theory the material from which the clusters are formed should constitute a fairly definite proportion of the total galactic raw material, and a larger galaxy should therefore provide material for more clusters. The Reciprocal System of theory asserts that the clusters are being drawn in from surrounding space, and that the more massive galaxies gather more clusters because they exert stronger gravitational forces throughout larger volumes of space.

  9. Observation: The distribution of clusters around the Galaxy is nearly spherical, and there is no evidence that the cluster system participates to any substantial degree in galactic rotation.

    Comment: This is difficult to reconcile with conventional theory. If the formation of the clusters was a part of the galaxy formation as a whole, it is hard to explain why one part of’ the structure acquired a high rotational velocity while another part of the same structure acquired little or none. B. Lindblad has suggested that the Galaxy is composed of sub-systems of different degrees of flattening, each rotating at a different rate. This, however, is simply a description, not an explanation. The Reciprocal System of theory provides a simple and straightforward explanation. According to this theory the clusters arc not part of the Galaxy, but are external objects being drawn into the Galaxy by gravitational force. On this basis the reason why the clusters do not participate in the galactic rotation is obvious. The nearly spherical distribution is also explained by the theoretically near uniform distribution of the clusters in the volume of space from which they were drawn.

  10. Observation: Interstellar distances in the outer regions of the globular clusters are comparable to those in the solar neighborhood. Present estimates are that the distances in the central regions are less by a factor of about eight.

    Comment: The significant point about the foregoing is that the variations in interstellar distance are relatively minor, and even in the locations of greatest density the distances between the stars are enormous. Conventional theory has no explanation for this state of affairs. In fact, the observed limitation on the minimum distance between stars is ignored in current astronomical thought, and close approaches of stars are features of a number of astronomical theories. The finding of this work is that the immense size of the minimum distance between stars (other than that between members of binary or multiple systems) is not accidental; it is a result of the inability of a star (or star system) to come within the gravitational limit of another. The stars do not approach each other more closely because they can not do so.

  11. Observation: The “orbits” of the clusters are rectilinear. As expressed by Struve in the statement previously quoted, the clusters “move much as freely falling bodies attracted by the galactic center.”

    Comment: Our findings are that this is exactly what they are, and that the observed motions are therefore just what we should expect. Conventional theory can explain such motions only by assuming extremely elongated elliptical orbits with relatively frequent passage of the clusters through the galactic structure. In view of the liquid-like nature of this structure, as deduced from the postulates that define the universe of motion, such passages through the galaxy are clearly impossible. Even without this information, however, it should be rather obvious that there is some reason why the observed minimum separation between the stars in the solar neighborhood (the only region in which we can determine the minimum) is so large. There is no justification for assuming that this reason, whatever it may be, is any less applicable to the stars of the globular clusters. The factors that determine this minimum separation bar the passage of any stellar aggregate through any other such aggregate, irrespective of what their nature may be. The conventional explanation of the observed inward motions of the clusters also conflicts with the following observation.

  12. Observation: Clusters closer to the galactic center are somewhat smaller than those farther out. Studies indicate a difference of 30 percent between 10,000 parsecs and 25,000 parsecs.

    Comment: If the “elongated orbit” theory were correct, the present distances from the galactic center would have no significance, as a cluster could be anywhere in its orbit. But the existence of a systematic difference between the closer and more distant clusters shows that the present positions do have a significance. Since the visible diameter of the average cluster is in the neighborhood of 100 light years, and the actual overall dimensions are undoubtedly greater, there is a substantial gravitational differential between the near and far sides of a cluster at distances within 100,000 light years. We can therefore deduce that the clusters are experiencing an increasing loss of stars as they approach the Galaxy, both by acceleration of the closest stars and by retardation of the most distant. The effect of slow losses of this kind on the shape of the aggregate is minor, and the detached stars remerge with the general field of stars that is present in the same zone as the cluster. The process of attrition is therefore unobservable in any direct manner, but we can verity its existence by the comparison of sizes as noted above. From the observed differences it appears that the clusters lose more than half of their mass by the time they reach what may be regarded as the capture zone, the region in which the gravitational action on the cluster structure is relatively severe.

    The loss of stars due to gravitational differentials is substantially less in the case of a cluster approaching a small elliptical galaxy. Thus we find that an elliptical galaxy in Fornax, a member of the Local Group with a mass of about 2×109 solar equivalents, ”contains about five globulars that are bigger than those in our galaxy.

  13. Observation: There is also an increase in the heavy element content of the cluster stars as the distance from the galactic center decreases.

    Comment: This is another systematic correlation with radial distance that contradicts the “elongated orbit” theory. It is also inconsistent with the currently prevailing assumption that the globular clusters are component parts of the Galaxy and were formed in conjunction with the rest of the galactic structure.

  14. Observation: The globular clusters range in size from a few tens of thousands to over a million stars. No stable stellar aggregates have been found between this size and the multiple star systems consisting of a few stars separated by very short distances comparable to the diameters of planetary orbits.

    Comment: This is a very striking situation for which present-day astronomical theory has no explanation. A study of the problem by S. Von Hoerner was able to conclude only that ”the reasons must lie in the original conditions under which the clusters were formed. This is true, but it is not an explanation. What is needed is the information derived from theory in Chapter 2, the nature of those “conditions under which the clusters were formed.” As brought out there, no star can be formed within the gravitational limit of an existing star or multiple star system, since the gravitational pull of that star or star system prevents the accumulation of sufficient star-forming material. (Division of existing stars, as we will see later, forms Binary and multiple stars, not by condensation of new stars.) Stars formed outside the gravitational limit of an existing star are subject to a net outward motion. The cluster is held together only by reason of the gravitational attraction that the cluster as a whole exerts on its constituent stars. A cluster must therefore exceed a certain minimum size in order to be gravitationally stable. Such clusters originate only where large numbers of stars are formed contemporaneously from dust and gas clouds of vast proportions.

The foregoing discussion has considered 14 sets of facts, derived from observation, that represent the most significant items of information about the globular clusters now available, aside from a few items that we will not be in a position to appraise until after some further background information has been developed. The deductions from the postulates of the universe of motion that have been described supply a full and detailed explanation of every one of these sets of facts. The performance of conventional astronomical theory, on the other hand, is definitely unsatisfactory, even if it is given the benefit of the doubt where definitive answers to the questions at issue are unavailable. Evaluation of the adequacy of explanations is, of course, a matter of judgment, and the exact score will differ with the appraiser, but an evaluation on the basis of the comments that were made in the preceding discussion leads to the conclusion that conventional theory provides explanations that are tenable, on the basis of what is known from observation, for only three of the 14 items (1, 6, 8). It supplies no explanation at all for five items (2, 7, 9, 10, 14), and the explanation it advances is inconsistent with the observed facts in 6 cases (3, 4, 5, 11, 12, 13). Five more sets of observations that are pertinent to this evaluation will be examined in Chapter 9, and with the addition of these items the total score for conventional astronomical theory is 4 items explained, 7 with no explanation, and 8 explanations inconsistent with observation. The significance of these numbers is obvious.