The Angular Momentum Issue

Because of the difficulty explaining the angular momentum aspect, some textbooks have resorted to hand waving arguments simply begging the readers to believe the result with no supporting evidence. One textbook makes the statement (ref. 1 p326) “Random motions of gas particles inevitably give a gas cloud some small overall rotation”. This statement clearly violates the second law of thermodynamics which requires that in any irreversible process, entropy must increase meaning chaos begets more chaos or disorder, thus preventing any unidirected motion. Another idea has been the passage of a nearby star whose tidal forces might impart rotation (ref. 2 p623). This has been discarded because of the overwhelming diffusive effects on the original cloud. Another indication of the angular momentum problem associated with the nebular process has surfaced recently when exoplanet hunters discovered that of the detected planets orbiting other stars; more than half have seriously inclined orbits relative to their star’s rotational axis with 6 in retrograde orbits (ref. 2 p18). (Example below, artist concept). Eps And A system-1Again, with hand waving arguments devoid of evidence, the investigators suggest that multiple planetary near encounters result in orbits being radically changed. Other articles contend that collisions with disk material tend to circularize orbits and make them more coplanar. Apparently, the nebular theorists want it both ways. Many times theorists construct nebular models for computers which require an initially existing protostar and attending disk shaped nebula both with rotation already present for their models to start. These models are considered to be contrived (ref. 5 p70) since they assume conditions that are truly biased toward a desired result.

If we use our solar system as a case study, we can show how acute the angular momentum problem is. Our solar system is believed to have begun as a gas and dust cloud with a mass approximately 1.1 times that of the sun. Only 0.2% of the sun’s mass was originally small particles of dust called interstellar grains from which the planetary bodies were made. The rest of the nebula consisted almost entirely of hydrogen and helium gas. Currently 98% of our solar system’s angular momentum is due to the dynamics of the solid bodies excepting the sun (ref. 2 p622). The sun, however, accounts for nearly all of the mass. For a contracting and rotating nebula, most of the angular momentum, according to traditional physics, should reside with the central mass of the system. The explanation given for this apparent paradox is that the 10% of the original nebula’s mass was present during the beginning of the planetary accretion phase and accounted for most of the angular momentum at that time. Over the next several million years most of the gaseous portion of the nebula is said to have diffused away into interstellar space because of the protosun’s heating. With much of the outer solar nebula and its angular momentum component as well gone, some theorists suggest that the protosun began slowing down its rotational speed as some remaining gaseous material with rotational inertia was ejected. This would result in decreasing angular momentum for the developing protosun thus shifting the angular momentum balance toward the outer bodies. The gas ejection mechanism cited involves a protosun magnetic field which interacted with in falling nebula gas creating polar jets which carries that gas plus other protosun material away (ref. 1 pp326-327). Using current observations as a guide, while there are some stars with energetic magnetic fields, they do not in general have copius amounts of matter being ejected, the only exceptions being degenerate non-gaseous stars such as neutron stars or pulsars. This author has only found one article so far suggesting there is observational evidence of these jets emanating from developing gaseous stars and that evidence is at best inconclusive (ref. 6 pp26-27).

The more likely scenario would be increasing rotation rate of the protosun while it is attached to the solar nebula and gas is continuing to fall inward. At some point, rotational friction with the solar nebula along with increasing heating by the protosun would cause the nebula to detach from the protosun. At this point, barring any more significant influx of material, the protosun’s angular momentum would be fixed with a gap developing between it and the nebular disk. The existence of this gap is supported by observing a number of nearby stars which hace disks of dust and gas surrounding them (ref. 7 pp39-41). (Artist concept below)AU Microscopii Birth Ring -3The protostar would continue to contract due to gravity with increasing rotation rate until central core temperatures rose to a point where nuclear fusion would begin. This would stabilize the newly developed star in size and rotation speed. The earlier suggestion that the protosun slowed its rotation shifting the angular momentum balance toward the planetary bodies clearly would not happen with this scenario. At this point we are left with the original question of why do we observe the current angular momentum distribution in our solar system? The question remains unanswered from a purely secular viewpoint but will be discussed later in the summary of current theories. Next, a critical examination of the cloud collapse premise will be done.


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