APOD: The Mysterious Rings of Supernova 1987A (2012 Feb 26)

[bystander]

http://asterisk.apod.com/viewtopic.php?f=31&t=27501

[Interested Observer]

Does anyone else, besides me, think the rings are bubbles of superheated gas which are escaping along the field lines of the star's magnetic poles? Sort of like an aurora but in reverse.

It seems to me that the poles of a star going supernova would be the first place from which the explosion would escape, given that the field would provide the least resistance at the poles. The lack of resistance might also mean the bubbles travel faster than the shock wave emanating along the plane of the ecliptic.

Also, the study of bursting bubbles has shown they become rings of smaller bubbles as they expand.

To me, these two concepts seem to adequately explain what has been observed. It doesn't seem so mysterious to me but, I'd appreciate any feedback, in case there's something I've missed.

[neufer]

Does anyone else, besides me, think the rings are bubbles of superheated gas which are escaping along the field lines of the star's magnetic poles? Sort of like an aurora but in reverse.

It seems to me that the poles of a star going supernova would be the first place from which the explosion would escape, given that the field would provide the least resistance at the poles. The lack of resistance might also mean the bubbles travel faster than the shock wave emanating along the plane of the ecliptic.

Also, the study of bursting bubbles has shown they become rings of smaller bubbles as they expand.

To me, these two concepts seem to adequately explain what has been observed. It doesn't seem so mysterious to me but, I'd appreciate any feedback, in case there's something I've missed.

You probably have the basic general idea correct.

However, it is very long road from having a correct basic general idea
to explaining the bewildering variety of observed Planetary Nebula.

[500pesos]

It's like seeing an hourglass from below.

[Chris Peterson]

You probably have the basic general idea correct.

However, it is very long road from having a correct basic general idea
to explaining the bewildering variety of observed Planetary Nebula.

It is perhaps confusing to introduce planetary nebulas here. The object in this APOD is not a planetary nebula, and its structure probably comes about by very different mechanisms.

[Chris Peterson]

Does anyone else, besides me, think the rings are bubbles of superheated gas which are escaping along the field lines of the star's magnetic poles?

Almost certainly, the structure seen in supernova remnants derives from asymmetries in the parent star or star system, which includes the fact that there is an axis of rotation, and a magnetic axis. The magnetic field is probably important in influencing the initial direction some material is ejected in. That said, I think that the magnetic field falls off rapidly, and is probably not a major factor in influencing subsequent structure.

[neufer]

You probably have the basic general idea correct.

However, it is very long road from having a correct basic general idea
to explaining the bewildering variety of observed Planetary Nebula.

It is perhaps confusing to introduce planetary nebulas here. The object in this APOD is not a planetary nebula, and its structure probably comes about by very different mechanisms.

I'm guessing that it is strongly connected to planetary nebula except that it is a "planetary nebula" made visible by a supernova/neutron star rather than a by UV radiation from a white dwarf.

[Chris Peterson]

I'm guessing that it is strongly connected to planetary nebula except that it is a "planetary nebula" made visible by a supernova/neutron star rather than a by UV radiation from a white dwarf.

I don't doubt that there are at least some similar mechanisms involved in producing the range of structures observed around both planetary nebulas and supernovas. But that doesn't change the fact that there is no planetary nebula here. Planetary nebulas are the result of a series of gentle expulsions of material from a lower mass star over a long period. The material in a supernova remnant is ejected violently and suddenly. High mass stars don't produce planetary nebulas.

Like I said, I think it is confusing to conflate planetary nebulas and supernova remnants.

[BMAONE23]

Just a supposition (hypothesis): The ring structure could be caused by Strong Magnetic activity from the progenitor star's being at solar maximum during the time of the event.
Could magnetic activity from the belts of Sun Spots above and below the stellar equator cause the ring effect noticed above and below the equatorial ring? The stronger magnetic field at the equator could hold the material to a lower velocity forming a slower propagating torus around the center of the hourglass.

[neufer]

I'm guessing that [the rings are] strongly connected to planetary nebula except that it is a "planetary nebula"
made visible by a supernova/neutron star rather than a by UV radiation from a white dwarf.

I don't doubt that there are at least some similar mechanisms involved in producing the range of structures observed around both planetary nebulas and supernovas. But that doesn't change the fact that there is no planetary nebula here. Planetary nebulas are the result of a series of gentle expulsions of material from a lower mass star over a long period. The material in a supernova remnant is ejected violently and suddenly. High mass stars don't produce planetary nebulas.

High mass stars don't produce the white dwarfs necessary to fully illuminate planetary nebulas.

The material that this supernova ejected violently and suddenly in 1987 is mostly
still inside all the rings under consideration here (which were expelled 20,000 years ago).

[Chris Peterson]

High mass stars don't produce the white dwarfs necessary to fully illuminate planetary nebulas.

Exactly. Nor do they produce planetary nebulas to be illuminated.

[neufer]

High mass stars don't produce the white dwarfs necessary to fully illuminate planetary nebulas.

Exactly. Nor do they produce planetary nebulas to be illuminated.

Semantics (again).

[Chris Peterson]

High mass stars don't produce the white dwarfs necessary to fully illuminate planetary nebulas.

Exactly. Nor do they produce planetary nebulas to be illuminated.

Semantics (again).

Sorry, I'm really trying to understand the point you're trying to make, and I can't. I don't follow how you are connecting planetary nebulas to this APOD.

Planetary nebulas are produced by successive waves of shells shed by low to middle mass stars at the end of their lives, which are then illuminated by the core of that star once it is exposed.

SN 1987A was a Type II (core collapse) supernova. The progenitor is now a neutron star or black hole, and is not illuminating the supernova remnant. Thus, this APOD is unrelated to planetary nebulas in two ways: a supernova, by definition, can't produce a planetary nebula, and a planetary nebula requires a central illumination source, which is not present in 1987A.

Perhaps you could help me to understand how discussing planetary nebulas makes anything about 1987A easier to understand.

[neufer]

Sorry, I'm really trying to understand the point you're trying to make, and I can't.

I believe that is a first for me.

I don't follow how you are connecting planetary nebulas to this APOD.

Planetary nebulas are produced by successive waves of shells shed by low to middle mass stars at the end of their lives, which are then illuminated by the core of that star once it is exposed.

SN 1987A was a Type II (core collapse) supernova. The progenitor is now a neutron star or black hole, and is not illuminating the supernova remnant. Thus, this APOD is unrelated to planetary nebulas in two ways: a supernova, by definition, can't produce a planetary nebula, and a planetary nebula requires a central illumination source, which is not present in 1987A.

Perhaps you could help me to understand how discussing planetary nebulas makes anything about 1987A easier to understand.

If nothing else:

If we can't figure out all the different planetary nebula morphologies I don't see how we can begin to figure out the morphology of the SN 1987A remnant (especially if these two are totally unrelated).

[Interested Observer]

Thanks for the feedback, guys.

I wasn't trying to understand or classify all types of nebulae. I am not an expert so, I'll leave that to the professionals. However, some of them believe that the shape of a nebula bears some relation to the magnetic field of the star which created it, regardless of how it died.

I was only discussing the formation of "hourglass/diabolo/dumbell" nebulae thought to be associated with supernovae, specifically relating to 1987A and its "mysterious" rings.

The hypothesis I was suggesting is that, during the "rebound" phase of the core collapse, matter escapes more easily from the magnetic poles of the star than from its equator. This matter would escape as two "bubbles", one at each pole. As the bubbles travelled away from the star, they would expand. Eventually, the bubbles would "burst" and break down into rings of smaller bubbles. These rings would continue travelling away from the star along the polar axis, expanding in diameter and circumference until they eventually dissipate. (The best analogy I can use for this is blowing smoke rings. A smoke ring persists long after it has left the initial conditions which created it.)

As for the thicker central ring, this is probably composed of matter expelled from the core after the initial phase of collapse, when the force of the shock wave is sufficient to overcome all resistance - gravitational and magnetic. The rotation of the star would likely cause this matter to escape in the form of a spinning and rolling torus, which would also expand in diameter and circumference until dissipation.

This hypothesis seems to explain the observed phenomena, hence my head-scratching at the use of the word "mysterious". To my mind, the real mystery is: why has the equatorial ring started glowing? Any thoughts?

[neufer]

This hypothesis seems to explain the observed phenomena, hence my head-scratching at the use of the word "mysterious". To my mind, the real mystery is: why has the equatorial ring started glowing? Any thoughts?

The fastest gaseous parts of the 1987 supernova explosion rammed into slow debris from 20,000 years ago.

[Chris Peterson]

The hypothesis I was suggesting is that, during the "rebound" phase of the core collapse, matter escapes more easily from the magnetic poles of the star than from its equator...

I think that the actual situation is extremely complex, and can't be broken down into any simple scenario like this. AFAIK the research that has been done on structure in supernovas has largely involved the use of supercomputers and finite-element analysis. Models show these lobed structures emerging as the result of an extremely complex interplay between many parameters. You can't point at any single thing to explain it.

[Interested Observer]

Ok, all this head-scratching is causing my hair to fall out.

Is it believed that the rings formed prior to the star going supernova? That is truly mysterious. How did the number "20,000 years ago" come about? Is that based on computer modelling?

Just as an aside, how's this for some symmetry? The large lobed structures observed as supernovae remnants look very similar to one type of electron orbital(d_z²). Weird.

[neufer]

[size=175][color=#0000FF]Eta Carinae [/color][/size][url=http://en.wikipedia.org/wiki/Wolf-Rayet_star][size=175]Wolf-Rayet star[/size][/url]

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Is it believed that the rings formed prior to the star going supernova? That is truly mysterious.

Giant & Supergiant stars with nuclearly unstable cores and gravitationally unstable surfaces are constantly shedding gas.

How did the number "20,000 years ago" come about?
Is that based on computer modelling?

Probably based upon Doppler measurements of radial speed.

Just as an aside, how's this for some symmetry? The large lobed structures observed as supernovae remnants look very similar to one type of electron orbital(d_z²). Weird.

Wolf-Ra(m)yet star