of old called them "planets"
they looked like planets when viewed with earth bound telescopes. Recently,
higher resolution telescopes showed them to be distant nebulae; results
of stars in their later life stages, cooling, and loosing much of their gassy
exterior. A magnetic field of the core caused by orbiting ions restrains the
jet to move only out of the poles. These jets send particles into that gas
causing the gas to glow and to also move out with increased velocity. There
can also be an unseen companion that drags material away from the dying star,
causing spiral/ring effects. Black holes are not necessarily involved. Theories
as to the true nature of these strangely shaped nebulae are still being developed.
Ultraviolet images in 1978 showed that dying stars continue
to blow winds long after they eject their outer gaseous layers. Then, from
1994 onward, startling detailed images by the orbiting Hubble telescope emerged.
Private discussions about them circulated in the astronomy world, but not
much was said publicly as these images completely upset previous theories
on the disposition of stars. See
Hubble Image nebula 0828
Image MyCn18 (MyCn18)
Image MZ3 ("Ant Nebula"; Menzel 3)
Image (Jodrell) ("Bug")
Hubble Image ("Boomerang")
Image ("Eta Cartinae")
Good reproductions of the Calabash, the Ant nebula and
other nebula images were published in the July, 2004 Scientific American
(some of these facts
and images are copied from that article). I came across the 0828 image by
accident a few years ago "somewhere on the internet".
Our present ignorance about how these nebula work is
often obscured by journalistic babble. E.g.: "New information ultimately upends
the best of theories. Progress is often disruptive. It clears out old niches
and prepares the way for big (and often disorientating ) leaps forward"
One characteristic evident of these hour-glass shaped
nebulae is that the are magnetically controlled. The nature and origin of
such magnetic fields have not been discussed in public as far as I can tell.
So I will venture an explanation:
Up to the present
such a star has been fusing hydrogen into nuclei of larger atomic
number (Z) along with the accompanying neutrons to make nuclei of atomic
weights (W) ever greater. The main star body has been so hot that electrons
no longer associate with the proton/neutron nuclei, so the nuclei bundle
together as gravity may attract them to one another while their positive
charge has also established a stable standoff distance. Thermal agitation
adds some standoff distance, on the average.
Fusion has advanced far past the atomic number of iron
Z=26, W=55, which we know on earth to divide exothermic fusions from the
exothermic FISSION of heavy atoms. There is so much extra energy, pressure
and density in the star interior, that it has become the natatorium for heavy
elements in my opinion. It is even likely that nuclei have been fused that
are beyond the highest Z (Neptunium, 93/237) that we know to exist on
our cool earth. Such higher Z nuclei are formed and decay with some equilibrium
and concentration, and likely have congregated near the center of a large
it is presumed that this sun-like star is now in a later stage of its life.
Previously, it enjoyed the above mentioned sun like life, being relatively
large in diameter and engaged in hydrogen gathering and hydrogen fusion for
some time. But of late it is becoming starved of hydrogen on its journey through
space. It has not encountered a fresh bounty of drifting hydrogen fuel. So
it decays, using up whatever hydrogen it previously stored. Or it might be
in a late cookie monster stage where it ate too much, got too big, and can
no longer satisfy its appetite for hydrogen cookies.
This aging star will have some rotational angular momentum,
as nothing is ever so still as to not possess any. The heavier nuclei gravitate
to the aging star's center in proportion to their atomic weight W; the heaviest
toward the core's center. At that moment, this is not important. Some
shells or strata of various radii may develop according to some preferred
groupings of similar nuclei.
the misfortune in its journey through space to not recently encounter some
drifting clouds of fresh hydrogen, this star begins to cool. In so cooling,
it shrinks in diameter as lower temperatures all around justify a smaller
radius. Soon, the rotational rate (spin) increases. The outer
spinning lamina shells will most certainly contain an excess of electrons.
Such a rotating shell of charges will evolve a magnetic field aligned along
the average axis of spin. Sub shells or spheres might develop where the angular
momentum was too small to homogenize or consolidate, so that a multipole star
mass will develop. But we will just concentrate on a one-body dipole-like
As cooling progresses, the star's overall radius shrinks, the spin
rate of those lamina, especially the core, that have shrunken increases dramatically
just as exhibition ice skaters demonstrate by drawing in their arms. The charged
lamina, likely gasses heavily charge with electrons that long ago were stripped
from their nucleus, comprise a strong circulating current that creates a
strong magnetic field with poles on the spin axis.
At the same time many high Z nuclei, really unstable
isotopes, will come to prominence as core density increases. Now it does
matter that the Highest Z nuclei are concentrated near the core center++
; as they are the least stable
of the lot and most prone to fission. As the core also cools, it's greater
pressure and density cause the high Z nuclei to be compressed ever closer
together, tending toward a critical mass Eventually, this core goes
into a soft critical condition where profuse and perhaps prolonged fission
occurs. The product nucleons are charged; each fission propels charged particles
having various velocities. The spun magnetic field is strong enough to constrain
their average journey to be only along the magnetic field lines; along either
direction of the the spin axis. Though launched in random directions, the
final velocity of these launched and positively charged nucleons is only along
the spin axis, in either direction.
Calabash Lives: Thus
the planetary nebulae Calabash evolves; Calabash lives! The expelled particle
jet encounters the low pressure of free space, expansion as a gas cloud occurs
as in the jet of a rocket, into a parabola of rotation. Similar jets occur
as we see in either end of this dying star, Calabash. A precursor, faint,
far ahead of the main plume and nearly on the projected spin axis, is seen
a signature of the "trigger" fission explosion responsible for generating
this impressive display. And we now know the evolution of the hour glass pattern
of planetary nebulae.
10 February, 2008 AJC.