APOD: Supernova Cannon Expels Pulsar J0002 (2019 Aug 13)

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neufer
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tiniest imbalance?

Post by neufer » Tue Aug 13, 2019 8:47 pm

Chris Peterson wrote:
Tue Aug 13, 2019 7:58 pm
BDanielMayfield wrote:
Tue Aug 13, 2019 7:32 pm

So then to compute the violence of this canon shot we also need to know the duration (time) it took to accelerate the stellar remnant. How long might this have taken?
Well, if it's a core collapse SN, most of the energy is released in the form of neutrinos, perhaps 1046 joules (with maybe 1% of that released in the kinetic energy of ejecta, and a tiny fraction as electromagnetic radiation). Most of this energy is released over a few hundred seconds. So really, just the tiniest imbalance of radiation could result in huge momentum imbalances of ordinary matter.
Note that the TOTAL momentum in ALL directions of 1046 newton meters worth of neutrinos

is 1046/c = 33.3 x 1036 newton seconds

or only about ten times more than that of today's APOD cannonball in a SINGLE direction.
https://en.wikipedia.org/wiki/Supernova#Asymmetry wrote:
<<A long-standing puzzle surrounding Type II supernovae is why the remaining compact object receives a large velocity away from the epicentre; pulsars, and thus neutron stars, are observed to have high velocities, and black holes presumably do as well, although they are far harder to observe in isolation. The initial impetus can be substantial, propelling an object of more than a solar mass at a velocity of 500 km/s or greater. This indicates an expansion asymmetry, but the mechanism by which momentum is transferred to the compact object remains a puzzle. Proposed explanations for this kick include convection in the collapsing star and jet production during neutron star formation.

One possible explanation for this asymmetry is large-scale convection above the core. The convection can create variations in the local abundances of elements, resulting in uneven nuclear burning during the collapse, bounce and resulting expansion.

Another possible explanation is that accretion of gas onto the central neutron star can create a disk that drives highly directional jets, propelling matter at a high velocity out of the star, and driving transverse shocks that completely disrupt the star. These jets might play a crucial role in the resulting supernova. (A similar model is now favored for explaining long gamma-ray bursts.)

Initial asymmetries have also been confirmed in Type Ia supernovae through observation. This result may mean that the initial luminosity of this type of supernova depends on the viewing angle. However, the expansion becomes more symmetrical with the passage of time. Early asymmetries are detectable by measuring the polarization of the emitted light.>>
Art Neuendorffer

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Chris Peterson
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Re: tiniest imbalance?

Post by Chris Peterson » Tue Aug 13, 2019 9:17 pm

neufer wrote:
Tue Aug 13, 2019 8:47 pm
Chris Peterson wrote:
Tue Aug 13, 2019 7:58 pm
BDanielMayfield wrote:
Tue Aug 13, 2019 7:32 pm

So then to compute the violence of this canon shot we also need to know the duration (time) it took to accelerate the stellar remnant. How long might this have taken?
Well, if it's a core collapse SN, most of the energy is released in the form of neutrinos, perhaps 1046 joules (with maybe 1% of that released in the kinetic energy of ejecta, and a tiny fraction as electromagnetic radiation). Most of this energy is released over a few hundred seconds. So really, just the tiniest imbalance of radiation could result in huge momentum imbalances of ordinary matter.
Note that the TOTAL momentum in ALL directions of 1046 newton meters worth of neutrinos

is 1046/c = 33.3 x 1036 newton seconds

or only about ten times more than that of today's APOD cannonball in a SINGLE direction.
But that does seem to assume that the neutrinos are radiated uniformly in all directions. I don't know if that's necessarily the case. This isn't my area of expertise. I wonder, though, if any supernova models support an asymmetry not just in the ordinary matter, but in the neutrino release.
Chris

*****************************************
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Cloudbait Observatory
http://www.cloudbait.com

Beotian

Re: APOD: Supernova Cannon Expels Pulsar J0002 (2019 Aug 13)

Post by Beotian » Wed Aug 14, 2019 12:22 pm

Speaking of cannonball and cannon
I wonder what kind of sling effect would result of a highly fast rotating binary star going SN ?

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Re: APOD: Supernova Cannon Expels Pulsar J0002 (2019 Aug 13)

Post by BDanielMayfield » Wed Aug 14, 2019 4:01 pm

Beotian wrote:
Wed Aug 14, 2019 12:22 pm
Speaking of cannonball and cannon
I wonder what kind of sling effect would result of a highly fast rotating binary star going SN ?
That is not a bad suggestion at all Beotian. The system could have started as a binary in which first one star goes SN, leaving a pulsar in an orbit about about another Star also destined to go SN. Some SN are expected to result in total disruption of the star, leaving no stellar core at all. If the second SN was of that type it would release the first star’s core to fly off in a straight line at the velocity of its orbit.

Bruce
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neufer
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Re: APOD: Supernova Cannon Expels Pulsar J0002 (2019 Aug 13)

Post by neufer » Wed Aug 14, 2019 8:51 pm

BDanielMayfield wrote:
Wed Aug 14, 2019 4:01 pm
Beotian wrote:
Wed Aug 14, 2019 12:22 pm

I wonder what kind of sling effect would result of a highly fast rotating binary star going SN ?
That is not a bad suggestion at all Beotian. The system could have started as a binary in which first one star goes SN, leaving a pulsar in an orbit about about another Star also destined to go SN. Some SN are expected to result in total disruption of the star, leaving no stellar core at all. If the second SN was of that type it would release the first star’s core to fly off in a straight line at the velocity of its orbit.
The fastest perihelion velocity a pulsar could have orbiting a pre- core collapse super-giant star is something like 350 km/s.
Art Neuendorffer

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Re: APOD: Supernova Cannon Expels Pulsar J0002 (2019 Aug 13)

Post by BDanielMayfield » Thu Aug 15, 2019 1:23 am

neufer wrote:
Wed Aug 14, 2019 8:51 pm
BDanielMayfield wrote:
Wed Aug 14, 2019 4:01 pm
Beotian wrote:
Wed Aug 14, 2019 12:22 pm

I wonder what kind of sling effect would result of a highly fast rotating binary star going SN ?
That is not a bad suggestion at all Beotian. The system could have started as a binary in which first one star goes SN, leaving a pulsar in an orbit about about another Star also destined to go SN. Some SN are expected to result in total disruption of the star, leaving no stellar core at all. If the second SN was of that type it would release the first star’s core to fly off in a straight line at the velocity of its orbit.
The fastest perihelion velocity a pulsar could have orbiting a pre- core collapse super-giant star is something like 350 km/s.
Ah shucks then. Well there goes that idea Beotian.
"Happy are the peaceable ... "

Beotian

Re: APOD: Supernova Cannon Expels Pulsar J0002 (2019 Aug 13)

Post by Beotian » Thu Aug 15, 2019 4:15 pm

BDanielMayfield wrote:
Thu Aug 15, 2019 1:23 am
neufer wrote:
Wed Aug 14, 2019 8:51 pm

The fastest perihelion velocity a pulsar could have orbiting a pre- core collapse super-giant star is something like 350 km/s.
Ah shucks then. Well there goes that idea Beotian.
I'll get over it. It's not the first good looking one that goes so fast.
Thank you for your answers.