Stellar Magnetic Fields

In article , "Robert L.
Oldershaw" writes:


[Mod. note: this paper suggests that the X-ray emission comes from the
corona of the star or from star-disc interactions; they certainly do
not say it is a 'point source at the center of the star' -- which is
of course impossible -- or that it is associated with the jets. -- mjh]

It is true that I "jumped the shark" a bit on my characterization of
the X-ray data.

That should probably be "jumped the gun" (a metaphor arising from track
and field sports where one should not start before the starting gun is
fired). "Jump the shark" refers to an episode of 1970s sitcom "Happy
Days" (which was set in the 1950s) where the Fonz character did indeed
jump a shark while waterskiing. It has since come to refer to an event
which is so lame that it is clear to all that there is no hope left
(usually within the context of television serials). Well, maybe you did
jump the shark here. :-)

[Mod. note: I've allowed this because it's informative and amusing,
but let's try to stay on topic -- mjh.]

On Dec 19, 8:15*am, Phillip Helbig---undress to reply
wrote:
In article , "Robert L.

Solar models are so detailed and so well checked that, after the
experiments were deemed good enough, people decided on "new physics"
(hence confirmed: neutrino oscillations, implying that neutrinos have
mass) rather than doubt the models.

But can these "so detailed" and "so well checked" models explain how
the Sun gets its magnetic field, and can these models tell us what is
going on with the Sun's enigmatic 22-year solar magnetic cycle, in
which the global dipole field and the sunspots flip polarity roughly
every 11 years?! Only with many untested assumptions and a whole lot
of mathematical hand-waving can the theorists come up with something
halfway plausible. No one regards these problems as solved with
present models. In astrophysics, many things can be explained; many
things cannot be explained. We would do well to keep an open mind
regarding the extent of our knowledge, and the lack thereof.

Most importantly, let us not pre-judge the outcome of the definitive
prediction before the testing is done. I say the jets of PB Piscium
will be traced to within 10 km of its geometric center. Conventional
astrophysics says that is completely impossible. Perfect! Now let us
allow NATURE to say who is right.

[Mod. note: how exactly do you propose to 'test' this proposition? -- mjh]

RLO
www.amherst.edu/~rloldershaw

[Mod. note: how exactly do you propose to 'test' this proposition? -- mjh]


In qualitative terms, exactly the same way as the jets in the giant
elliptical galaxy M87 were gradually traced to the very center of the
galaxy.

[Mod. note: M87 is transparent to photons at a wide range of
wavelengths. A star is not -- mjh]

And exaxctly the same way that "totally unobservable" atoms
can now be, at least indirectly, observed.

To be perfectly honest I have no idea what methods that are currently
well-known and/or those that are currently unknown will be required to
test this prediction.

However, I have very little doubt that the definitive prediction will
be tested. Hopefully direct tests will be possible, but if not, then
at least indirect testing will be posible.

Perhaps very sophisticated stellar seismology will be required to be
developed and then utilized in the case of BP Piscium. Perhaps clever
research scientists will figure out a way to test this prediction
using methods we know about but have never considered applying in this
type of context.

Bottom line: The deep internal structure of stars is far too important
a research area to remain largely unexplored. If there is a will, then
a way will be found.

RLO
www.amherst.edu/~rloldershaw

Quick Version: The central regions of some "coreless" planetary
nebulae should contain Kerr-Newman ultracompact objects and/or neutron
stars.

Longer Version: Planetary nebulae offer a good class of test systems
for testing the definitive prediction that all stellar objects have K-
NU nuclear objects at their centers. In these systems the star has
ejected one or more plasma envelopes, which have such beautiful and
highly suggestive morphologies (a comparison with the morphologies of
the electronic wavefunctions of atoms is quite remarkable). Note that
the energies involved in PNs are are roughly 6 orders of magnitude
lower than the energies of supernova. Therefore, according to
conventional astrophysics, K-NU nuclei and neutron stars are 'not
supposed to form' in PN events.

In some cases a low-mass star could conceivably eject all of its
plasma envelopes and the only thing remaining at the center would be
one of the hypothesized K-NUs or neutron stars. It would not be a
trivial matter to identify such an object at the center of a PN
because the PN are very large and many candidate central sources would
have to be asessed and ruled out. However, this test is definitely
feasible now with existing technology.

Some relevant information:

(1) A significant fraction of PN do not have confidently identified
central objects. Some are referred to as "coreless". These would be
good target systems.

(2) The lower the mass of the original star, the higher the
probability of an event that removes everything but he hypothesized K-
NU nucleus.

(3) The recently (2008?) discovered undesignated "Cygnus Bubble" PN,
which is very faint and almost perfectly spherical, is a very
interesting test system. After detective work by astronomers, a very
blue stellar object was detected at geometric center. Isolated neutron
stars also have been found to be blue in color when they have been
imaged. Obviously, this central object needs to be looked at very
carefully, but I have not yet found a really thorough scientific study
of it.

(4) The hyothesized K-NU nuclei would be expected to be potential
emitters of Gamma-rays, X-rays and radio waves, depending on their
state of excitation and mode of de-excitation. Therefore the Chandra
and Fermi data might provide very useful identification and diagnostic
information.

(5) If one neutron star turned up near the center of a "coreless" PN,
one could not infer too much about it. But if many ultracompact
objects were found at the centers of "coreless" PN, then random chance
could rapidly be ruled out.

Happy Solstice,
RLO
www.amherst.edu/~rloldershaw

At this point I would like to refine the R and B estimates used to
arrive at the 1/R^2 scaling for the global dipole B fields of
"magnetic" subclasses of several major classes of stars.

The equation under consideration is: B = B* / (R/R*)^2 , where
the * designates the average values of B and R for neutron stars.

In log form the equation is: log B = 13.25 - 2 log R/R*

For neutron stars: log R* = 6.0 and log B* = 13.25

For white dwarf stars: log R = 9.0 and log B = 6.0

For M dwarfs: log R = 10.3 and log B = 3.5

For beta Cepheids: log R = 11.3 and log B = 2.2

For O,B,A,F,G Giant stars: log R = 11.9 and log B = 0

When you plot this up, you get a straight line that is approximated by
the log equation given above.

If one should doubt that the R and B values I use are appropriate,
I would appreciate being directed to empirical data that would suggest
other R and B values that might be more appropriate.

Happy Holidays,
RLO
www.amherst.edu/~rloldershaw

[[Mod. note -- I've taken the liberty of changing the subject line from
" Stellar Magnetic Fields" to "planetary nebulaa and neutron stars",
since this article really doesn't have much to do with stellar magnetic
fields.
-- jt]]

If you read "Central Stars of Planetary Nebulae:...catalogue" which
can be obtained at this link: http://arxiv.org/PS_cache/arxiv/pdf/...010.5376v1.pdf
,

then you know that:

(1) of roughly 3,000 PNs that are known, the majority of their central
stars have not been identified and spectroscopically studied,
and
(2) of the the central stars that have been studied, a significant
percent are classified as "blue" objects.

Isolated neutron stars have been observed optically, for example see:
http://iopscience.iop.org/1538-4357/..._588_1_L33.pdf
and the Nature paper of 1997 by Walter and Matthews. One can also
search on Mignani's research on the spectroscopy of neutron stars via
arxiv.org.

The main point is that the above references note that neutron stars
are observed as being very "blue" objects when they can be observed in
the optical range.

My question, and here I need more than a little help from experienced
astrophysicists, is as follows. Could the "blue" objects at the
centers of many (some) planetary nebulae be neutron stars? If one
compares the spectroscopic (and other) data for the two classes of
"blue" objects, might there be a provocative overlap?

If there is a significant overlap, then I think we have something to
write home about, so to speak.

Happy New Year (but I suggest that you drink fine coffee instead of
that crankcase oil),
RLO
www.amherst.edu/~rloldershaw

In article
,
"Robert L. Oldershaw" writes:

(1) of roughly 3,000 PNs that are known, the majority of their central
stars have not been identified and spectroscopically studied,

OK.

and
(2) of the the central stars that have been studied, a significant
percent are classified as "blue" objects.

OK.

Isolated neutron stars have been observed optically, for example see:
http://iopscience.iop.org/1538-4357/..._588_1_L33.pdf
and the Nature paper of 1997 by Walter and Matthews. One can also
search on Mignani's research on the spectroscopy of neutron stars via
arxiv.org.

The main point is that the above references note that neutron stars
are observed as being very "blue" objects when they can be observed in
the optical range.

OK.

My question, and here I need more than a little help from experienced
astrophysicists, is as follows. Could the "blue" objects at the
centers of many (some) planetary nebulae be neutron stars? If one
compares the spectroscopic (and other) data for the two classes of
"blue" objects, might there be a provocative overlap?

If there is a significant overlap, then I think we have something to
write home about, so to speak.

Save your stationery. Most have not been observed. Some have been
observed. Neutron stars are blue. It's a big jump to assume that the
unobserved ones are neutron stars. Lots of stellar objects are blue.
More significantly, those that have been observed are NOT neutron stars.

I don't know who owns most of the expensive cars in my town. The few
owners I do know are rich. NBA players are rich. Should I assume that
most of the expensive cars in my town are owned by NBA players?

On Jan 3, 11:15 pm, (Phillip Helbig---
undress to reply) wrote:

I don't know who owns most of the expensive cars in my town. The few
owners I do know are rich. NBA players are rich. Should I assume that
most of the expensive cars in my town are owned by NBA players?


Be my guest. But these quaint analogies bear no resemblance to my
reasoning, thank you.


Save your stationery. Most have not been observed. Some have been
observed. Neutron stars are blue. It's a big jump to assume that the
unobserved ones are neutron stars. Lots of stellar objects are blue.
More significantly, those that have been observed are NOT neutron stars.

If one has an adequate understanding of the new paradigm I work
within, then one knows that I expect the overwhelming majority of PN
nuclei to compact high-temperature stars, as is observed in the small
fraction of PN nuclei that have been studied carefully.

The case wherein all of the original star's shells have been ejected,
leaving a bare neutron star-like nucleus, should be far less probable.
Perhaps only 1% to 10% of PNN will be of this type. So it is very
premature for you to assume that my prediction is ruled out. It most
certainly has not been ruled out, if we are deciding by scientific
methods.

The type of system I am predicting: a planetary nebula with a neutron
star-like nucleus will most likely be found at the center of faint
spherical PN such as the Soap Bubble Nebula PN G75.5+1.7, which was
mentioned earlier in this thread.

When we have characterized the PN nuclei of 100 faint systems, and at
least 100 of the more typical PN systems, then we will have enough
hard data to say with some scientific confidence, rather than bluster
or wishful thinking, whether or not there is a definite overlap
between the observed properties of isolated neutron stars and some PN
nuclei.

RLO
www.amherst.edu/~rloldershaw

PS: If anybody wants to see a graph showing that the B and B-max
values for various star classes fit my 1/R^2 conjecture rather well,
send me an email and I will attach the graph to the return email.

In article ,
"Robert L. Oldershaw" writes:
(2) of the the central stars that have been studied, a significant
percent are classified as "blue" objects.

"Blue" isn't quantitative, but all PN central stars should have
temperatures above 30000 K.

Could the "blue" objects at the
centers of many (some) planetary nebulae be neutron stars?

Nothing I know rules out a PN central star having a neutron star
companion, but I don't see how a neutron star (only a few km in
diameter) could produce enough ionizing photons to keep the nebula
ionized. Central star temperatures are known from the nebular line
ratios, so you can't do it just by cranking up the temperature.

This is aside from pretty good stellar evolution theory.

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA

In article ,
"Robert L. Oldershaw" writes:
I am formally proposing that the central nuclei
of a subset of PNae will consist of SINGLE objects, and that these
nuclei can be approximated by unaccompanied neutron stars.
.....
Let's do the observational testing FIRST

Perhaps you might have another look at the part about ionizing
photons. Where do you think they're coming from, if the central
object is something like a neutron star?

--
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA