The violent birth of neutron stars

[stephen63]

(Phys.org) —A team of researchers at the Max Planck Institute for Astrophysics conducted the most expensive and most elaborate computer simulations so far to study the formation of neutron stars at the center of collapsing stars with unprecedented accuracy. These worldwide first three-dimensional models with a detailed treatment of all important physical effects confirm that extremely violent, hugely asymmetric sloshing and spiral motions occur when the stellar matter falls towards the center. The results of the simulations thus lend support to basic perceptions of the dynamical processes that are involved when a star explodes as supernova.

Read more at: http://phys.org/news/2013-06-violent-bi ... s.html#jCp

[neufer]

(Phys.org) —<<A team of researchers at the Max Planck Institute for Astrophysics conducted the most expensive and most elaborate computer simulations so far to study the formation of neutron stars at the center of collapsing stars with unprecedented accuracy. These worldwide first three-dimensional models with a detailed treatment of all important physical effects confirm that extremely violent, hugely asymmetric sloshing and spiral motions occur when the stellar matter falls towards the center. The results of the simulations thus lend support to basic perceptions of the dynamical processes that are involved when a star explodes as supernova.

Click to play embedded YouTube video.

[b][color=#0000FF][size=150]Shallow Water Analogue of Shock Instability[/size] Credit: Thierry Foglizzo, Laboratoire AIM Paris-Saclay, CEA[/color][/b]

---

Many Terabytes of simulation data had to be analysed and visualized before the researchers could grasp the essence of their model runs. What they saw caused excitement as well as astonishment. The stellar gas did not only exhibit the violent bubbling and seething with the characteristic rising mushroom-like plumes driven by neutrino heating in close similarity to what can be observed in boiling water. The scientists also found powerful, large sloshing motions, which temporarily switch over to rapid, strong rotational motions. Such a behavior had been known before and had been named "Standing Accretion Shock Instability", or SASI. This term expresses the fact that the initial sphericity of the supernova shock wave is spontaneously broken, because the shock develops large-amplitude, pulsating asymmetries by the oscillatory growth of initially small, random seed perturbations. So far, however, this had been found only in simplified and incomplete model simulations.

"My colleague Thierry Foglizzo ... has constructed an experiment, in which a hydraulic jump in a circular water flow exhibits pulsational asymmetries in close analogy to the shock front in the collapsing matter of the supernova core." This phenomenon was named "SWASI" ("Shallow Water Analogue of Shock Instability") and allows one to demonstrate dynamical processes in the deep interior of a dying star by a relatively simple and inexpensive experimental setup of table size of course without accounting for the important effects of neutrino heating. For this reason many astrophysicists had been sceptical that this instability indeed occurs in collapsing stars.

The "SWASI" experiment demonstrates the dynamical processes in the supernova interior by a circular water current that is fed by a ring-shaped reservoir and flows radially over a curved surface towards a central pipe, where it exits the experimental setup. The deceleration before entering the pipe leads to a backwater step in the water flow, a so-called hydraulic jump. The water corresponds to the collapsing gas in the supernova core, the pipe mimics the matter accreting neutron star, and the hydraulic jump plays the role of the stagnant supernova shock in the stellar core. For ideal conditions the hydraulic jump stays nearly circular. When the water flow is increased, the symmetry is broken because an instability leads to the oscillatory growth of violent sloshing motions or spiralling motions of the whole region enclosed by the hydraulic jump. This "SWASI" phenomenon is an analogue of the SASI instability occurring in the supernova core, but it is one million times smaller and about one hundred times slower than its astrophysical counterpart.>>

[geckzilla]

There's a simulation video in the middle of that article that's amazing.

[JohnD]

Indeed!
Horribly repellant, like a raidly mutating fungus, or a cancer growing.

Got to be an APOD candidate!
JOhn

[neufer]

Click to play embedded YouTube video.

Indeed!

Horribly repellant,

like a rapidly mutating fungus, or a cancer growing.

[Beyond]

Well... that was sure sumtin

[JohnD]

Actually, that was a pretty good translation of a laparotomy into a dramatic scenario.
Very simplified, and the incision is in fact made in stages through the layers of the abdominal wall, rather than one slash.
And even current robotic surgery kit is several light years in advance of what was shown, which was more like an amusement arcade crane game.
But the rapid fire wound stapler would be a real advance on sometimes slow surgeons!

Joke is, that pair of tongs that came down and pulled out the alien ?foetus? looks to have been made from an actual pair of obstetric forceps, for gripping the head of a baby when complications of normal delivery mean that the baby needs help to rotate and progress out into the world.

Maybe I'm hardened, but surgery is surgery, and it's not horrific at all. And a lot slower than that!
That scene was IMHO nothing like as horrible as that neutron star simulation, which gave every appearance, unlike the mini-squid, of malign and purposeful life.

John

[neufer]

.

Maybe I'm hardened, but surgery is surgery, and it's not horrific at all.
And a lot slower than that!

• Tell that to Noomi Rapace.

That scene was IMHO nothing like as horrible as that neutron star simulation,
which gave every appearance, unlike the mini-squid, of malign and purposeful life.

<<Squidward Quincy Tentacle is careless, ill-tempered, pretentious, cynical, and grouchy. He intensely despises his neighbors for their perpetual laughter and constant boisterous, noisy behavior and play. Squidward lives in a neverending state of self-pity and misery, aggravated and unhappy with the lifestyle he currently leads, and yearns for celebrity status and a far more glamorous and distinguished career as a celebrated musician or painter, with a passion for Art and playing the clarinet. However, he is left to endure through the lowly status as a fast-food cashier at the Krusty Krab restaurant, a position which he deeply resents, irritated by both his cheap and greedy employer Mr. Krabs and having SpongeBob as a co-worker.>>

[JohnD]

Ah! You refer to the film "The Girl with the Dragon Tattoo", in which you might not have bene so surprised by the violence if it had retained the original Swedish title, "Men who hate women". Anyway that was ACTING, neufer. Surgery isn't acting, though it does involve prima donnas, and that neutron star ain't acting, neufer, it IS evil!

John

[neufer]

Ah! You refer to the film "The Girl with the Dragon Tattoo", in which you might not have been so surprised by the violence if it had retained the original Swedish title, "Men who hate women".

Click to play embedded YouTube video.

<<Noomi Rapace is also known for playing lead role of Dr. Elizabeth Shaw in the Ridley Scott science fiction film Prometheus (2012). A medical scan reveals that Shaw, despite being sterile, is pregnant. Fearing the worst, she uses an automated surgery table to extract a squid-like creature from her abdomen.>>

Anyway that was ACTING, neufer. Surgery isn't acting, though it does involve prima donnas, and that neutron star ain't acting, neufer, it IS evil!

Without properly accounting for the effects of neutrino heating the dynamical processes in the deep interior of a dying star shown at:
http://phys.org/news/2013-06-violent-bi ... s.html#jCp

might just represent OVER-ACTING!

[geckzilla]

Abridged surgery may have had somewhat correct bits but the girl's anatomy was so wrong and the situation was so absurd I almost laughed out loud at that scene in the theater.

[bystander]

The Violent Birth of Neutron Stars
Max Planck Institute for Astrophysics | 2013 Jun 27

SASI Activity in Three-Dimensional Neutrino-Hydrodynamics Simulations of Supernova Cores - F. Hanke et al

• Astrophysical Journal 770(1) 66 (2013 Jun 10) DOI: 10.1088/0004-637X/770/1/66
  arXiv.org > astro-ph > arXiv:1303.6269 > 25 Mar 2013 (v1), 19 Jun 2013 (v2)

A Shallow Water Analogue of the Standing Accretion Shock Instability:
Experimental Demonstration and Two-Dimensional Model - Thierry Foglizzo et al

• Physical Review Letters 108(5) 051103 (Feb 2012) DOI: 10.1103/PhysRevLett.108.051103
  arXiv.org > astro-ph > arXiv:1112.3448 > 15 Dec 2011

[neufer]

Abridged surgery may have had somewhat correct bits but the girl's anatomy was so wrong and the situation was so absurd I almost laughed out loud at that scene in the theater.

The Violent Birth of Neutron Stars
Max Planck Institute for Astrophysics | 2013 Jun 27

SASI Activity in Three-Dimensional Neutrino-Hydrodynamics Simulations of Supernova Cores - F. Hanke et al

• Astrophysical Journal 770(1) 66 (2013 Jun 10) DOI: 10.1088/0004-637X/770/1/66
  arXiv.org > astro-ph > arXiv:1303.6269 > 25 Mar 2013 (v1), 19 Jun 2013 (v2)

A Shallow Water Analogue of the Standing Accretion Shock Instability:
Experimental Demonstration and Two-Dimensional Model - Thierry Foglizzo et al

• Physical Review Letters 108(5) 051103 (Feb 2012) DOI: 10.1103/PhysRevLett.108.051103
  arXiv.org > astro-ph > arXiv:1112.3448 > 15 Dec 2011