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StarLab
2004-Oct-15, 07:05 PM
Magnetic Stars Puzzle Solved by Astrophysicists (http://www.spaceref.com/news/viewpr.html?pid=15294)

Check out the above paper, which I found on SpaceRef.

Here is their brief: How does one explain the enormous magnetic field strengths of the so-called magnetic stars? This question concerning magnetic fields in the cosmos, first posed half a century ago, has now been answered by scientists of the Max Planck Institute.

VanderL
2004-Oct-15, 09:03 PM
Hi Starlab,

Thanks for this article, I had seen this item in German, glad you found it in English.
All in all I am far from convinced that the model is true. I have trouble believing in fossil magnetic fields, it is a bit comparable to dark matter, imo. In both cases there is an observation (magnetism or the rotation curves of galaxies), that can't be matched to current theory (the one's we apply to local phenomena). The apparent solution then is to explain it using "new physics" (all the dark matter candidates, and in this case fossil magnetic fields). It doesn't convince me, all the more because it will be very hard to experimentally confirm the role of magnetic fields in the formation of stars. Anyway, that's my thoughts,

Cheers.

zephyr46
2004-Oct-16, 04:21 AM
Any idea what the connection is to Soft Gamma Ray Repeaters (http://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search?Magnetars)? Anomalous X-ray Pulsars (http://antwrp.gsfc.nasa.gov/apod/ap010901.html) and SGRS, same thing?

I know that light is effected by magnetism, are X and gamma rays effected in the same way?

Thanks for the topic :)

I am still trying to understand the objects associated with LBV 1806 - 20 (http://www.solstation.com/x-objects/1806-20.htm), which includes a SGR (1806 -20)


The cluster includes at least two carbon-rich, Wolf-Rayet stars (WC9d and WCL), two blue hypergiants, and a neutron star, the soft gamma-ray repeater SGR 1806-20

Eikenberry et al (http://www.solstation.com/x-objects/1806-20.htm) (cited Solstation)

Fascinating! :)

wstevenbrown
2004-Oct-18, 05:03 PM
Enclosed, find a letter I sent 15 Dec. 03 to a prominent supernova expert at a local University. He never replied, being a very busy man. Bypassing history for the moment, I never found it necessary to invoke fossil fields. In an ionizing environment (such as a thermonuclear device: a star, for instance), the positive and negative charges, however briefly separated they would have been in low-or-no-gradient electrical field, are both subject to the diurnal rotation of the object. Moving electrical charges result in a magnetic field where none was before, because charges of different polarities have different self-interaction with their own fields, as well as different geodesics from interacting with any pre-existing field. Thus, as soon as the charges begin to segregate, the field can bootstrap itself.


Dear Prof. Chevalier:
I am a new correspondent, with a naive question for the astrophysical community at large. Has anyone managed to link the magnetic field of a white dwarf to the shape of the planetary produced, or the microvariability of the central object? In Kaler's excellent book , Extreme Stars, he mentions that whether the dwarf is DA or non-DA, the outer atmosphere is highly, almost totally ionized. I infer that whatever rotation the original star had will have been increased by the shrinking of its radius; whatever magnetic field it had will have been intensified by the shortened interpolar distance. We then seem to have a lot of conduction electrons being subjected to a strong, rotating magnetic field-- they will move, but how? I suggest that they travel in repetitive closed paths (Hamiltonians) both on and under the surface, that these paths are phase-locked to the rotation (not necessarily 1:1), and form essentially standing waves whose rotation period is trigonometrically related to that of the stellar surface. Different depths will have differing densities/ionizations/conductivities, so differing, but qualitatively similar patters must persist in the interior. If such patterns exist, they will be observable in at least one, and possibly two ways: radiation will be anisotropic, and from the observer's point of view this will manifest as microvariability on a timescale of minutes, due to the rotation. There may be a similar fluctuation in the polarization of the emitted radiation, though I would expect a weaker signal, probably swamped by the merely sonic effects of intermittent nuclear ignition in such a small, dense body. I note from the literature that such microvariability as has been observed is usually ascribed to starspots, but I find this unconvincing as a complete explanation.

I see a number of planetaries that appear to be tetrapolar, almost tetrahedral in shape. During the final collapse of the star (and its magnetic field), the last stable conduction pattern prior to the cataclysmic blowoff might have been a closed loop shaped like the seams of a baseball, which has that kind of symmetry. Spherically symmetric planetaries could be caused by more complex tiling patterns, whose details would be washed out by ordinary turbulence. Bipolar nebulae could be caused either by opposed equatorial loops, or by close companion stars. Eta Carinae, for example, does not appear to have a close companion, and its 5.5 year companion is too far out to cause the bifurcation without leaving a ruffled surface on the bipolar ejecta which would be amplified over time. I do suggest, however, that its orbit is aligned with the plane of symmetry. Finally, of course, there are a lot of weird objects that admit of no easy explanation.

I would appreciate any comment you might have on these armchair musings. Thank you, in any case, for the time already spent.

Yours truly, Steve Brown


Back to the present. It occured to me in l'esprit de escalier (literally, spirit of the stairs-- what the French call that feeling you have when you come up with the witty comeback after the door has closed behind you), that starspots are magnetic phenomena which could be frozen in place by a larger-scale magnetic field, also phase-locked to the rotation. But, hey-- that's my style. I always backfill the details later.

I would appreciate comments from an astrophysicist, and of course all the other members present-- does any of this stuff make sense to you? Thanks, S.

zephyr46
2004-Oct-20, 04:32 AM
Thats way over my head! Can you draw me a picture? :D

While your at it, can some one help me?

I am trying to figure out the distance to the "Mouse (http://chandra.harvard.edu/photo/2004/mouse/index.html)" (see also Galactic center (http://rsd-www.nrl.navy.mil/7213/lazio/GC/)).

(16000 ly, :rolleyes: )

This document (http://www.jb.man.ac.uk/~drl/publications/cmgl02.pdf) puts it at less than 5.5 kpc and a sqiggly equal sign 2kpc, so are we talking roughly 6000 light years?

om@umr.edu
2004-Dec-05, 09:20 AM
Thanks for the interesting post, StarLab.

I cannot endorse VanderL's response.

Originally posted by VanderL@Oct 15 2004, 09:03 PM
I have trouble believing in fossil magnetic fields, it is a bit comparable to dark matter, imo.
In fact, Professors Stig Friberg, Barry Ninham and I concluded that the Sun's magnetic fields must also be "deep-seated remnants of ancient origin."

See: “Superfluidity in the solar interior: Implications for solar eruptions and climate”, Journal of Fusion Energy volume 21 (2003) pages 193-198
*
http://www.umr.edu/~om/abstracts2003/jfe-s...perfluidity.pdf (http://www.umr.edu/~om/abstracts2003/jfe-superfluidity.pdf)
*
I do not know of another viable explanation for the long-term memory of solar magnetic fields.

With kind regards,

Oliver
http://www.umr.edu/~om

Duane
2004-Dec-05, 11:38 PM
A tip of my hat to you Oliver, although the mechanism you propose for the fossle magnetic field is different, it seems you did indeed get the idea correct.

In fact, in reading this paper, I suggest the deep seated solar magnetic field probably arose in the same basic manner as that for the WD & NS simulations done in this study. That is, the magnetic field arose in the cloud of gas forming the sun and is a "relic" of those field lines.

VanderL, you don't like it because it doesn't support the EU theory of star formation. Also you are just wrong when you call it "new physics", the idea of relic magnetic fields has been a topic of hot study for years. It certainly meets our current understandings of physics better than most of the other theories I've seen.

Steve, that seems like an interesting treatise. I can;t say I have the background to give a yay or nay, but it sounds intrigung.

om@umr.edu
2004-Dec-06, 12:36 AM
Originally posted by Duane@Dec 5 2004, 11:38 PM
A tip of my hat to you Oliver, although the mechanism you propose for the fossil magnetic field is different, it seems you did indeed get the idea correct.
Thanks, Duane.

As usual in science, a large part of the credit for this idea properly belongs to earlier researchers.

1. Reference #25 is to a quote by Dr. Marcia Neugebauer, "There may be something asymmetric about the Sun's interior, perhaps a deep-seated lump of old magnetic field", in a JPL news release on 1 February 2000.

http://www.appliedmeditation.org/The_Heart...cosmic_sun.html (http://www.appliedmeditation.org/The_Heart/cosmic_sun.html)

2. Reference #2 is to Professor Barry W. Ninham's (ANU) startling conclusion in 1963 that fresh supernova debris may undergo Bose-Einstein condensation of the iron-rich, zero-spin material into a superfluid superconductor.

Barry W. Ninham, Physics Letters, volume 4 (1963) pages 278-279.

With kind regards,

Oliver
http://www.umr.edu/~om