Based on computer
simulations Mark Krumholz from Princeton University,
Christopher McKee from the University of California at Berkeley, and Richard
Klein from Berkeley and Lawrence Livermore National Laboratory now claim [Nature 438, 332-334 (2005)] that the bottom-up theory is incorrect because
the seeds cannot grow fast enough during the lifetimes of the clouds to reach
typical star sizes. …
"Our result is that
the bottom-up idea doesn't work," Krumholz told PhysicsWeb,
"because seeds can't accrete quickly enough to grow to stellar masses
within the lifetimes of the clouds out of which they are born. Instead, stars
form by fragmentation, and the fragmentation process determines their
The results also explain,
the team says, why observations suggest that objects as different as small
brown dwarfs and massive stars have a common formation mechanism. In contrast,
the accretion model involves different mechanisms for making objects with
different masses. A universal formation process might also explain why the mass
distribution of newly formed stars – the initial mass function – seems to be
constant throughout our galaxy and other galaxies.
simulations of star formation processes made a significant error because they modelled environments with properties that are very
different from those observed," says Krumholz.
"A lot of these simulations are now going to have to be reconsidered and
How do stars form?
Belle Dumé, PhysicsWeb, 16
Toward that ultimate end, therefore, kindly consider here a
suggestion for your further thought.
The “universal formation process,” referred to above, is
indeed an observational fact today (please see also the recent ESO Letters).
Not surprisingly in this fractal universe of ours, the final model that has
thus come to light is also an extremely simple one. The essentials, taken from
my book and web Synopsis are
as follows – with the optical map of Fig. 3.9 (page 41) in P. J. E. Peebles’ Principles of Physical Cosmology,
Princeton University Press (1993), in perspective.
The latticework of the observable universe
Astronomical observations reveal
the fact that the large star ends its active life in a spectacular supernova.
The ejected matter from such exploding nuclear bodies then go to form a new
generation of smaller stars. All these star types we are able to directly
observe as discrete bodies in the firmament and thereby make these correct
is also not inconceivable, therefore, that the large stars we see today were themselves once ejected from even larger nuclear entities –
the galactic cores. But it is not possible even with the best of instruments to
observe the galactic core directly to ascertain this process. Whereas the
supernova debris eventually clears to reveal a core, the fog around the
galactic center never lifts. As a result, the nucleus of our own Milky Way
Galaxy, for example, remains obscured at all time by the stars and the gas
clouds of what we call the central bulge. This shroud never dissipates due to
the relentless activity within, which feeds and sustains it. Nevertheless,
recent endeavors have revealed to refined instruments and observational
techniques enough evidence to show that the region of the galactic core is
indeed a hub of violent activity of sustained
star formation (Serabyn & Morris 1996).
so long ago, the central bulge was commonly thought to consist mostly of very
old stars. But, now, there is also convincing evidence to suggest that star
formation has been occurring near the center of the bulge throughout the
lifetime of the Galaxy. Thus, the most energetic of expulsions from the
galactic core are what we see mostly as stars and star clusters outside the
back in time, a very close or contiguous union of such galactic cores (that is,
in their extremely active and formative years) is what we observe, in time
lapse now, as the quasar. Quasars and their ilk, collectively known as active
galactic nuclei, or AGN, are the greatest cosmic powerhouses known today. The
AGN, in turn, would evolve from even larger and denser mass centers. The
existence of such super centers, though, is not presently recognized,
suspected, or even speculated.
us here refer to these ultimate mass centers, dispersed across observable
space, simply as – COSMIC CORES.
to the cover provided by the AGN outside, Cosmic Cores, too, remain out of
direct view like galactic cores. But here, too, indirectly, there is ample
evidence to support such centers in our observable universe. For example, the
Cosmic Cores would possess most of the mass in our universe (like atomic nuclei
do in a body of matter); and it is only such extremely massive and compact
bodies (in the foreground) that could possibly account for the otherwise
enigmatic gravitational lensing of (distant) quasars
(Fischer et al. 1994).
what would be the true function of Cosmic Cores?
astronomers and astrophysicists, especially, the function of Cosmic Cores
should not seem something that is at all new. Even this aspect of the cosmic
process is seen today in miniature down the line. We say that large stars die
in the supernova and generate new stars. But the first part of this statement
we also know is not generally true. That is to say, the remains of a so-called
dead star would live again – for a repeat death performance another day – if
the environment is right: The dense and extinct core, typically, a neutron
star, exerts an enormous gravitational influence on all that is around in the
vicinity and grows by accreting matter; in time, it would eject matter in a
nova- or even a supernova-like event once again. In principle, therefore, there
is no end to these epochs for the selfsame stellar core – if sufficient matter
is (cyclically) provided. In the case of the Cosmic Cores dotting our universe,
however – there just happens to be sufficient matter around (from a critical
initial condition) to keep the process going indefinitely.
A Universe of Steady State
In actual fact, the Cores
of the cosmic latticework feed each other. That is, they accrete matter, fuse
them together, and toss them out at each other. Matter, from the galaxy supercluster to the atom, is thus continually recycled in
our observable universe. And the cosmic species of the heavens continue to live
on in their eternal splendor.
for this grandiose and cyclic mass transfer through cosmic space, too, is very
well established now, though it remains a challenge to today's standard model:
The periodicity of birth of galaxy cluster groups and the uniformity of their
spacing and speed are truly breathtaking that they even make the observers to
double-check their instruments in disbelief! (Smoot &
Davidson 1993; Matthews 1996).
is thus plainly seen that galaxies are not scattered more or less randomly
through space as had once seemed the case. Indeed, galaxies are aggregated as
sheets of clusters and superclusters. It is like a cosmic foam where the walls of the bubbles are
concentrations of galaxies. As a balance to these huge concentrations, immense
voids also exist between sheets (Saar et al. 2002).
as NASA's Hubble Space Telescope (HST) continues to confirm only too
overwhelmingly, galaxies abound even at the deepest levels of observable space.
Not only did the HST capture new galaxies in earlier "empty" space,
but it also got a better look at some of the lumpy ones that had been seen
before. Seen in the infrared, they look more like "normal" galaxies,
like those in our own cosmic neighborhood. Clearly, cosmic structures do not
seem to have changed over time across observable space – as if in a
steady-state universe (see, for instance, Schilling 1999).
concept of the conservation of energy would also suggest a steady-state
universe. Until only as recently as a decade ago it was difficult to reconcile
all of the observed data to a steady-state universe. But, now, the powerful
telescopes of the present day throw to us much more light
than they receive. And, in this most revealing new light since the time of
Einstein, we see the awe-inspiring final picture emerging.
celestial body has a closed-loop trajectory beginning in a Cosmic Core and
ending in a neighboring one only to be regenerated, or, to be born again. And a
steady-state universe would go on existing, ceaselessly, under the setting...
all began and how it all will end are outside the realm
of observation. They, thereby, remove themselves also outside the
scope of physics.
(References listed in Synopsis.)
Thank you for your valuable time; I'm confident it will not
be found a waste.