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rgatley
2007-Feb-23, 03:01 PM
Concerning the two faint rings surrounding the "string of pearls" light echo: Are we looking at a light echo from an earlier event? Think Eta Carinae geometry.

trinitree88
2007-Feb-23, 03:57 PM
Concerning the two faint rings surrounding the "string of pearls" light echo: Are we looking at a light echo from an earlier event? Think Eta Carinae geometry.

rgatley. Welcome to the forums. The geometry of Type 2 core collapse supernovae (1987a...morphological characteristics) is fairly well understood. Most remnants are devoid of pulsars. Free ranging pulsars are seen in pulsar surveys(Lyne, Harrison, Cordes). Radio maps of supernovae remnants indicate they are predominantly barrel-shaped 48/60 (R.N. Manchester, M.J. Kesteven, Aust. J. of Physics, Molonglo Observatory Synthesis Telescope, Epping, N.S.W.circa 1988..) .
The evidence indicates inherent asymmetry in type 2's. They are not spherical and their use as standard candles requires adjustment for viewing angles. They only look spherical when viewed along the barrel axis. Their progenitor's stellar winds are also suspected of being bipolar emission similar to 'planetary' nebulae.
The expectation that the detonation of a type-2 is asymmetrical is built on the theoretical underpinnings of parity effects in weak interactions, a universal effect in weak decays. (T.D.K.Lee, and C.N. Yang. Columbia 50's). Proponents of using them as standard candles have overlooked the inherent asymmetry often. The geometry of Eta C is clearly a good model for the progenitor's pre-explosion shape.
The asymmetry is sometimes large enough to eject the pulsar from the galaxy's gravitational field, at velocities approaching 1% c. Escape velocity runs ~400 km/sec for most galaxies. Other,slower pulsars are bound to their host galaxies. Pete.

rgatley
2007-Feb-23, 04:51 PM
Thanks Pete....one event then with an asymmetric explosion, the light echo illuminating an "hourglass geometry"? Seems like there is a denser annular torus? normal to the long axis of the explosion also (the bright ring) or could it be of a different composition? Apologies if these questions illuminate my own ignorance... Rick.

StupendousMan
2007-Feb-23, 09:15 PM
The expectation that the detonation of a type-2 is asymmetrical is built on the theoretical underpinnings of parity effects in weak interactions, a universal effect in weak decays. (T.D.K.Lee, and C.N. Yang. Columbia 50's).

I agree with Pete that some Type II supernovae show clear asymmetry in their explosions, or their remnants. However, the papers I read ascribe the asymmetry to very large-scale factors, such as the rotation of the progenitor, or the presence of a binary companion, or random variations in the progress of the nuclear burning through the core, or turbulence in and around the shock layer. I do not understand how parity effects at the sub-atomic level could show themselves in the very macroscopic realm of supernova ejecta.

Could you please explain, Pete?

satori
2007-Feb-23, 09:49 PM
what about magnetic fields ,88 ?

trinitree88
2007-Feb-24, 01:27 PM
I agree with Pete that some Type II supernovae show clear asymmetry in their explosions, or their remnants. However, the papers I read ascribe the asymmetry to very large-scale factors, such as the rotation of the progenitor, or the presence of a binary companion, or random variations in the progress of the nuclear burning through the core, or turbulence in and around the shock layer. I do not understand how parity effects at the sub-atomic level could show themselves in the very macroscopic realm of supernova ejecta.

Could you please explain, Pete?

StupendousMan. OK. Years ago, I gave a talk at Vassar College.(AAPT Meeting, Nov.92)..Parity, Pulsars and Supernova Remnants. In it I showed a scatter plot from an article, "A Survey of Southern Pulsars " from I believe MNRAS (I'll check). It showed a plot of observed transverse velocities in km/sec versus residual magnetic field strength ~ 1011 to 1013 Gauss. The coefficient of correlation for the scatter plot was ~0.7...anything higher than 0.3 is statistically significant. That means there's a component of a pulsars' birth velocity that is coupled to the field strength.
It is generally believed that as a pulsar forms, the residual field in the progenitor is locked in, so one can infer that the stronger the field during core collapse, the higher the transverse velocity. As it happens, the Russian theorists, Leinson, and Oraevskii, published in the Soviet Journal of Nuclear Physics an article on neutrino bimodal scattering in core collapse supernovae. The primary scattering involved neutrino/quark-gluon bag scattering, and was symmetrical. The secondary scattering was neutrino/magnon scattering (spin waves), contributed an additional 30% to the overall scattering and enabled them to produce an explosion which solved the Supernova problem...escape velocity was reached. The crosssection here is coupled to the B field. It is asymmetrical due to parity effects.
Parity effects are universally seen in all weak interactions, every experiment, every run (nobody had bothered to check when T.D.K.Lee and C.N. Yang made their hypothesis). One can define an asymmetry here as Nnorth-Nsouth/Nnorth+Nsouth. MIT had run a parity experiment at the Bates Linear Accelerator on He-3, circa 1992. In it they used a partially polarized gaseous target. The neutrons anti-align and cancel out, so the effect in the proton could be measured..~ 4%., and that's in the electromagnetic interaction. It can be as large as 40% in the weak interaction. So I added it to the Leinson-Oraevskii Secondary Scattering (neutrino/magnon) to see where the numbers would go. It yields a maximum transverse velocity of ~ 3000 km/sec, order of magnitude close to the observations, assuming a 10% scattering transfer of energy and momentum (J.Cronin, Notre Dame). As an added plus, one can predict that the pulsar will always be ejected from the same magnetic pole of the precursor....bottle of Chianti, Vassar. You can even with some confidence predict the elements of orientation of future pulsars, and their transverse/radial velocity components from the field strengths of their progenitors. (I gave a pair of talks on this at the Bates Accelerator and the Laboratory for Nuclear Science, Cambridge at MIT during the summer of 93 while on a NSF TRAC Fellowship, and a follow-up activity at the Harvard AAPT Meeting the following spring.) Pete

StupendousMan
2007-Feb-24, 03:00 PM
The paper Pete refers to in his post above is "The proper motions of six southern radio pulsars", by Bailes et al., published in MNRAS, vol 247, p 322 (1990). You can find a link to its abstract and full text on the ADS system:

Look for yourself at the paper (http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1990MNRAS.247..322B&db_key=AST&page_ind=0&plate_select=NO&data_type=GIF&type=SCREEN_GIF&classic=YES)

The crucial point of this paper for Pete's claim is its Figure 3, on page 325. Look for yourself. There does appear to be a correlation, but it's not a particularly strong one.

There has been a lot of work in this field over the past fifteen years. For example, here are a list of papers describing the proper motions of pulsars measured recently.

ADS query for pulsar proper motions (http://adsabs.harvard.edu/cgi-bin/nph-abs_connect?db_key=AST&db_key=PRE&qform=AST&sim_query=YES&ned_query=YES&aut_logic=OR&obj_logic=OR&author=&object=&start_mon=&start_year=2002&end_mon=&end_year=&ttl_logic=OR&title=&txt_logic=OR&text=pulsar+proper+motions+magnetic+moment&nr_to_return=100&start_nr=1&jou_pick=ALL&ref_stems=&data_and=ALL&group_and=ALL&start_entry_day=&start_entry_mon=&start_entry_year=&end_entry_day=&end_entry_mon=&end_entry_year=&min_score=&sort=SCORE&data_type=SHORT&aut_syn=YES&ttl_syn=YES&txt_syn=YES&aut_wt=1.0&obj_wt=1.0&ttl_wt=0.3&txt_wt=3.0&aut_wgt=YES&obj_wgt=YES&ttl_wgt=YES&txt_wgt=YES&ttl_sco=YES&txt_sco=YES&version=1)

There has also been quite a bit of research into the source(s) of the initial kicks given to pulsars when a supernova explodes. Here are the results of an ADS search using keywords "pulsar kick supernova:"

Recent papers discussing pulsar "kicks" (http://adsabs.harvard.edu/cgi-bin/nph-abs_connect?db_key=AST&db_key=PRE&qform=AST&sim_query=YES&ned_query=YES&aut_logic=OR&obj_logic=OR&author=&object=&start_mon=&start_year=2002&end_mon=&end_year=&ttl_logic=OR&title=&txt_logic=OR&text=pulsar+kick+supernova&nr_to_return=100&start_nr=1&jou_pick=ALL&ref_stems=&data_and=ALL&group_and=ALL&start_entry_day=&start_entry_mon=&start_entry_year=&end_entry_day=&end_entry_mon=&end_entry_year=&min_score=&sort=SCORE&data_type=SHORT&aut_syn=YES&ttl_syn=YES&txt_syn=YES&aut_wt=1.0&obj_wt=1.0&ttl_wt=0.3&txt_wt=3.0&aut_wgt=YES&obj_wgt=YES&ttl_wgt=YES&txt_wgt=YES&ttl_sco=YES&txt_sco=YES&version=1)

Perhaps we all ought to do some reading; it looks like there are quite a few ideas.

trinitree88
2007-Feb-24, 04:00 PM
Stu. Thanks for the link. That's the scatter plot I used. Correlation is not causation, but suggests it. As a gambling man, I figured I had nothing to lose except my reputation as a physicist, and as I'm a chemist, I still had that to fall back on..lol. So I stuck my neck in the guillotine of scientific inquiry willingly, and predicted the effect. Since it's presumably due to an asymmetry in the weak interaction, and the pulsar recoils from it, I named it in honor of the late Gene Roddenberry...the Weak Asymmetric Recoil Phenomenon...or W.A.R.P. Drive. Except this is real, not Trekkie fantasy.
Considering a typical pulsar of approximately ~ one solar mass, roughly one million Earth masses, forming in about 5-10 seconds...(as evidenced by the length of the prompt neutrino burst from 1987a, even though higher core densities could allow faster collapse, and a slight time-delayed burst). It accelerates at ~ 104 g's. This is real. I called the speed of light c, WARP 10 to stay within SR, and the ejecta can reach ~c/10 or.. WARP 1(Fillipenko, 1987a, Ap.J.)...that's several percent of the energetics of the explosion for a big one ~20 solar masses, and the pulsar gets ~ WARP 0.08
Since escape velocity for the galaxy runs ~ 470/km/sec tops, and some pulsars are faster than this......high gravitational redshift objects, can, and do escape nearby galaxies. There's even a remote chance a million mph pulsar will run through the roof of your house in the next million years, but I wouldn't lose any sleep over it.;) Pete.