Thursday, November 01, 2007

New Spin on Stars


The "Angular Momentum Problem" is yet another puzzle of astrophysics. Since the time of Pierre Laplace, scientists have believed that stars collapse from rotating disks of gas. If the disk angular momentum were conserved, a star would spin itself apart before igniting. Where does the angular momentum go? One big clue is the powerful jets seen erupting from infant stars. The jets follow magnetic field lines, as if angular momentum were powering huge electric dynamoes.

In the November 1 issue of NATURE, astronomers from the Anglo-Australian Observatory put forth a model where the jets carry away angular momentum. Infrared observations of protostar HH135-36 in the Carina Nebula show jets extending billions of kilometres. The photo of HH 135-36 is a bit fuzzy because infrared wavelengths are long. This model is also recounted in Space.com. The exact mechanism turning angular momentum to magnetism is still considered a mystery.

Twin jets following magnetic field lines are signs of a Black Hole. Today's Washington Post recounts how astronomers realised that Black Holes are at the centre of galaxies. This conclusion took decades of work. "Something very profound is going on here, and the formation of Black Holes and galaxies is related in some way," states astrophysicist Juna Kollmeier. It may take more decades to figure out that a Black Hole is in the second last place humans would expect. It may be rising in front of our faces every morning.

Like an electron, a Black Hole can be described by just three numbers: Mass, spin and electric charge. In an electron, these numbers are quantized into discrete values. As if they were produced on an assembly line, every electron has the same charge and mass! Researchers like Carl Brannen are hot on the trail of particle masses. Black Holes, on the other hand, can have almost any mass.

Lower than a certain mass Black Holes are prone to evaporate in Hawking radiation. There is almost no upper limit to Black Hole size; they could be huge enough to clear A Hole in the Universe. For that reason Black Holes are likely to form a majority of the "dark" mass. They could be ubiquitous, seeding formation of galaxies, stars and even smaller objects. The protons, neutrons and electrons that form life compose only 4.507034% of the Universe. It is amazing that we add up to that much.

More Space news is in the new Carnival of Space!

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3 Comments:

Anonymous Anonymous said...

The work of Chrysostomou et al was also mentioned in a comment on Carl Brannen's guest blog on Tommaso's blog, so if it is OK (if not because of duplication, please feel free to delete this) here are some things I said there about helical magnetic fields.

According to an ESO web page at www.eso.org/public/outreach/press-rel/pr-2006/phot-45-06.html
“… Spatial, three-dimensional distribution of galaxies in a slice of the Universe as it was 7 billion years ago, based on the VVDS study … the galaxy distribution - the ‘building blocks’ of the large scale structure - takes the shape of a helix at this primordial epoch …”,
so
it may be that helical magnetic fields might be involved in galaxy formation as well as in star formation.

Further, Battaner et al, in in astro-ph/9801276, astro-ph/9802009, and astro-ph/9911423, suggest that the simplest network pattern for distribution of superclusters of galaxies that is compatible with magnetic field constraints is made up of octahedra contacting at their vertexes,
which is related to a tiling of 3-dim space by cuboctahedra and octahedra,
and also to the heptaverton of Arthur Young( www.arthuryoung.com/ ) in his book The Reflexive Universe (Robert Briggs Associates 1978), and octonionic structures of Onar Aam.

Further, with respect to the angular momentum problem, it is interesting that, for astronomical things from stars to asteroids, there seems to be a nice linear relationship between mass and angular momentum.

Still further, there also seems to be a nice linear relationship between angular momentum and magnetic dipole moment. It may even extend to laboratory-scale phenomena. AFAIK, the latest experimental discussion was by Saul-Paul Sirag in a 2000 paper in which he said in part:
"... The most straightforward test ... would be to measure directly the magnetic field of a rotating neutral body (which is not also a ferromagnetic substance). Blackett ... suggested that a 1-meter bronze sphere spun at 100 Hz would do nicely, except that this is the maximum safe speed, and there are severe problems in nulling out extraneous magnetic fields. With modern SQUIDs and mu-metal shielded rooms, such an experiment can be attempted. Exactly such an experimental design ... was described at the SQUID '85 conference in Berlin. However, the results of this experiment have not been published. ...".
Such a relationship would connect Gravity with ElectroMagnetism in interesting ways, and may be related to work of Tajmar et al in gr-qc/0603033 where they say that the effects they observe are "... are 30 orders of magnitude higher than what general relativity predicts classically ...".

Some relevant material (including graphs) are on my web pages at
tony5m17h.net/angmomemag.html
and
tony5m17h.net/Mar2006Update.html#ogvphtn

Tony Smith

7:50 PM  
Blogger L. Riofrio said...

Interesting as always, tony. There is also a direct relationship between galaxy bulge and Black Hole mass, which may apply to smaller objects as well. Linear mass relationships seem to apply to many objects, from small planets up. The difference between planets, brown dwarves and stars could be just a matter of mass.

8:04 PM  
Blogger Matti Pitkanen said...

I realize of having managed to pass by the angular momentum problem for all these years! Thank you for opening my eyes!

In TGD framework I find it easy to believe in dynamo explanation: angular momentum would be transferred to em fields and dark matter particles at the flux quanta of these fields defining the "field body" of the object. Funny that the angular momentum problem has not been seen as a direct evidence for the presence of dark matter.

TGD based model for the asymptotic state of star (gravitational four-momentum conserved locally that is curvature scalar for induced metric extremized) indeed predicts dynamolike structure with E and B orthogonal from the mere simplifying assumption that CP_2 projection is 2-D.

Also the existence of string like magnetic flux tube around rotation axis is predicted and jets would flow naturally along them. Many-sheetedness allows several symmetry axes (axis of rotation and symmetry axis of jet are not identical for Earth or supernovas).

A further prediction is the concentration of mass strongly at the surface of the star. Together with the notion of many-sheeted space-time one ends up to predict an onionlike structure consisting of mass shells corresponding to different p-adic length scales: the analogy with atomic shells is suggestive and supported by macroscopic quantum coherence of dark matter in astro scales.

The linear relationship between mass and angular momentum follows naturally if cosmic strings (in TGD sense) gradually thicknened to magnetic flux tubes during cosmic evolution are the basic objects. The Universe is very "stringy" but in a sense different from what superstring hegemony would like it to be.


Matti

10:53 PM  

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