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Date Posted: 08:38:46 10/28/15 Wed
Author: Pahu
Subject: Star Births? Stellar Evolution? 2



Star Births? Stellar Evolution? 2



If stars evolve, star births should about equal star deaths. Within our Milky Way Galaxy alone, about one star dies each year and becomes an expanding cloud of gas and dust (b). The less frequent deaths of more massive stars are much brighter, more violent explosions called supernovas. Star births, on the other hand, would appear as new starlight not present on the many photographic plates made decades earlier. Instruments which could detect dust falling into and forming supposedly new stars have not done so (c). Actually, stars that some astronomers believe are very new are expelling matter. We have seen hundreds of stars die, but we have never seen a star born (d).



b. These explosions were misnamed “planetary nebula,” because early astronomers with evolutionary ideas thought these clouds were forming planets around new stars. [See Bruce Balick and Adam Frank, “The Extraordinary Deaths of Ordinary Stars,” Scientific American, Vol. 291, July 2004, pp. 50–59.]


“Herschel...speculated they might be planetary systems taking shape around young stars. The name stuck even though the opposite turned out to be true; this type of nebula consists of gas molted from dying stars. ... [Planetary nebula] pose challenges to stellar evolution theory, the physics that describes the life story of stars.” Ibid., p. 52.


c. “...no one has unambiguously observed material falling onto an embryonic star, which should be happening if the star is truly still forming. And no one has caught a molecular cloud in the act of collapsing.” Ivars Peterson, “The Winds of Starbirth,” Science News, Vol. 137, 30 June 1990, p. 409.


“Precisely how a section of an interstellar cloud collapses gravitationally into a star—a double or multiple star, or a solar system—is still a challenging theoretical problem.... Astronomers have yet to find an interstellar cloud in the actual process of collapse.” Fred L. Whipple, The Mystery of Comets (Washington, D.C.: Smithsonian Institution Press, 1985), pp. 211–212, 213.


d. “Yet astronomers have never witnessed [even] a high-mass star being born, and hotly debate how they form.” Eric Hand, “Mega-Array Reveals Birthplace of Giant Stars,”
Nature,Vol 492, 20/27 December 2012, p. 320.

This 1.4 billion dollar mega-array is being builtin hopes ofseeing a star being born. The birth of high-mass stars would be the easiest to see. So far, no births have been seen.

“The origin of stars represents one of the most fundamental unsolved problems of contemporary astrophysics.” Charles J. Lada and Frank H. Shu, “The Formation of Sunlike Stars,”
Science,Vol. 248, 4 May 1990, p. 564.


“Most disturbing, however, is the fact that, despite numerous efforts, we have yet to directly observe the process of stellar formation. We have not yet been able to unambiguously detect the collapse of a molecular cloud core or the infall of circumstellar material onto an embryonic star. Until such an observation is made, it would probably be prudent to regard our current hypotheses and theoretical scenarios with some degree of suspicion.” Ibid., p. 572.


[From “In the Beginning” by Walt Brown ]

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