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Fraser
2005-Aug-18, 05:09 PM
SUMMARY: One of the most famous supernovae in recent memory is SN 1987A, which exploded in the Large Magellanic Cloud. Before its death, the star produced a ferocious stellar wind that carved out a large bubble in the surrounding, colder gas. When it went supernova, a shockwave traveled out in space, and astronomers have been waiting in anticipation for the shockwave to slam into the edge of this bubble. New images from NASA's Chandra X-Ray Observatory shows that this stage now appears to be underway.

View full article (http://www.universetoday.com/am/publish/chandra_xray_supernova_1987a.html)

What do you think about this story? Post your comments below.

om@umr.edu
2005-Aug-18, 05:58 PM
Another great story, Fraser.

The axial directed explosion of SN1987A was a major astronomical discovery.

Before his death, Dr. Sabu and I were anxiously awaiting each new result from that event.

With kind regards,

Oliver
http://www.umr.edu/~om

Eric Vaxxine
2005-Aug-19, 09:14 AM
There is something to be said about being able to watch an event that happened 160,000 light years ago.
Time travel.
If we travelled far away enough, we would be able to observe how the earth was formed, maybe?
(we'd need to take hubble and chandra with us)

om@umr.edu
2005-Aug-19, 10:28 AM
Originally posted by Eric Vaxxine@Aug 19 2005, 09:14 AM
There is something to be said about being able to watch an event that happened 160,000 light years ago.

Time travel.

If we travelled far away enough, we would be able to observe how the earth was formed, maybe?
Thanks, Eric, for the message.

You are exactly right.

We know a supernova exploded 5 billion years ago, at the birth of the solar system and a lot of the debris (short-lived elements, isotopic anomalies, chemical variations) were inherited by the material that formed meteorites and planets here.

We suspect that an axially directed SN explosion was involved, since this might not mix the SN debris completely.

That is exactly why Dr. Sabu and I were delighted to have a nearby supernova exploding in this fashion.

We wanted to see how the solar system formed.

With kind regards,

Oliver
http://www.umr.edu/~om

Eric Vaxxine
2005-Aug-19, 02:05 PM
Oliver, How long will you have to wait to see what you want?

:rolleyes:

Guest_om@umr.edu
2005-Aug-19, 04:51 PM
Originally posted by Eric Vaxxine@Aug 19 2005, 02:05 PM
Oliver, How long will you have to wait to see what you want?

:rolleyes:
We have already see a great deal of what we expected.

Perhaps a while longer for events measured by short-lived isotopes.

For example, some refractory grains in meteorites formed within 1-2 million years after a supernova.

In terms of geological time, that is darn short.

In terms of our lifespan, it is almost an eternity.

With kind regards,

Oliver
http://www.umr.edu/~om

Astra
2005-Aug-19, 07:04 PM
If we travelled far away enough, we would be able to observe how the earth was formed, maybe?
(we'd need to take hubble and chandra with us)

I don't think you could see that far back, could you :blink:

Jerry
2005-Aug-19, 09:01 PM
...the star lost most of its outer layers in a slowly moving stellar wind that formed a vast cloud of gas around it; before the star exploded, a high-speed wind blowing off its hot surface carved out a cavity in the cool gas cloud.

That's one guess, but IAOTO not the best one:

http://arxiv.org/PS_cache/astro-ph/pdf/031...311/0311484.pdf (http://arxiv.org/PS_cache/astro-ph/pdf/0311/0311484.pdf)

John Middleditch & others argue >95 of supernova explosions, including 1987A, are binary events, and the proof is in both the focused 'gamma rays from hell", and the donut shape of the expansion ring.

It is very difficult to impossible to model either the ring, or the gamma ray, in a single star collapse, while with binary events, the gamma ray focusing and ringed expansion are the predicted, natural consequences. The high percentage of binary systems 'out-there' mean binary collapses are inevitable. What do they look like, if not ringed supernova?

Double neutron star binaries are being observed today, and there is a possibility one of these events will be observed as it occurs in our lifetimes...If the big scope time is granted for monitoring these events.

http://arxiv.org/abs/astro-ph/0405068

Stay tuned...

cran
2005-Aug-20, 01:49 AM
I believe the 'ring' is also a predicted outcome of a single star event; as the 'main sequence' nears its end, the massive star enters a 'pulse' phase where it blows off much of its outer layers - a series of releases several orders of magnitude greater than coronal mass ejections... there are some stars within our own galaxy (and in near neighbours) that we are now observing in this process... the 'pulse' phase ends usually with the final core collapse... it may be that the supernova shockwave's interaction with these outer layers leads to the formation of CAIs, and other turbulence-induced compounds... providing the 'seeds' for further accretion... :unsure:

Jerry
2005-Aug-22, 05:09 PM
Originally posted by cran@Aug 20 2005, 01:49 AM
I believe the 'ring' is also a predicted outcome of a single star event; as the 'main sequence' nears its end, the massive star enters a 'pulse' phase where it blows off much of its outer layers - a series of releases several orders of magnitude greater than coronal mass ejections... there are some stars within our own galaxy (and in near neighbours) that we are now observing in this process... the 'pulse' phase ends usually with the final core collapse... it may be that the supernova shockwave's interaction with these outer layers leads to the formation of CAIs, and other turbulence-induced compounds... providing the 'seeds' for further accretion... :unsure:
...

I would be happier with either model if anyone had used it to predict ring, rather than spherical, expansion BEFORE the ring was observed...in fact, for a loooong time after the ringed structure of 1987 was visually apparent, we were told the rings were 'optical illusions', and the 'true' expansion was actually spherical. (I think you may still hear this explanation at a planetarium show - I have heard a TA use it as recently as Fall '2004'.)

om@umr.edu
2005-Aug-22, 05:55 PM
Originally posted by The Messenger@Aug 22 2005, 05:09 PM
I would be happier with either model if anyone had used it to predict ring, rather than spherical, expansion BEFORE the ring was observed...in fact, for a loooong time after the ringed structure of 1987 was visually apparent, we were told the rings were 'optical illusions', and the 'true' expansion was actually spherical. (I think you may still hear this explanation at a planetarium show - I have heard a TA use it as recently as Fall '2004'.)
Hi, Messenger.

The ring around the collapsed supernova core is indeed intriguing.

Do you think it might be related to the rocky planets found orbiting Pulsar 1257+12?

With kind regards,

Oliver
http://www.umr.edu/~om

cran
2005-Aug-22, 05:56 PM
Yes, I heard (or read) that one, too... ;) and there may still be some part of the story in that...
but more recently, I came across an article (now buried among thousands of similar interesting bits of news :blink: ) describing the remnant nebula of another supernova explosion ... the silicates and organics predominated in sort of clumpy broken donut (the ring, I guess) around the core remnant (a neutron star, I think... :huh: ) and the ferrics seemed to predominate in two diffuse and spreading 'polar' (I use that term nervously, to indicate locations at opposite points from the origin, I don't know if there is any connection with the star's rotational poles) lobes ... and then there was something about why it might have happened that way... that the outer layers were shed first (the 'pulse' phase - but I'm sure there's a better term for it... probably named after whoever first described it... :unsure: ) ... and the ferrics were released in the final collapse... :mellow: ... soooo, it might be that the actual supernova explosion is roughly spherical but the signal indicators from the less dense material overwhelms the indicators from any ferrics...? :unsure:

cran
2005-Aug-22, 05:59 PM
:blink: of course, it might have been the other way &#39;round :rolleyes: ... until (unless?) I find the original article I read, that uncertainty will bug me....>thinks< rotten unpredictable memory&#33; :angry:

om@umr.edu
2005-Aug-22, 06:14 PM
Originally posted by cran@Aug 22 2005, 05:56 PM
1. . . . more recently, I came across an article (now buried among thousands of similar interesting bits of news :blink: ) describing the remnant nebula of another supernova explosion ... the silicates and organics predominated in sort of clumpy broken donut (the ring, I guess) around the core remnant (a neutron star, I think... :huh: ) and the ferrics seemed to predominate in two diffuse and spreading &#39;polar&#39; (I use that term nervously, to indicate locations at opposite points from the origin, I don&#39;t know if there is any connection with the star&#39;s rotational poles) lobes ... and then there was something about why it might have happened that way... that the outer layers were shed first (the &#39;pulse&#39; phase - but I&#39;m sure there&#39;s a better term for it... probably named after whoever first described it... :unsure: ) ... and the ferrics were released in the final collapse... :mellow:

2.... soooo, it might be that the actual supernova explosion is roughly spherical but the signal indicators from the less dense material overwhelms the indicators from any ferrics...? :unsure:
Hi, Cran.

1. An axial explosion would likely produce minimal mixing of material in the equatorial plane, leaving supernova debris orbiting the collapsed supernova core.

An axial explosion might also leave unmixed clumps of organics and silicates and iron (ferrics) in the newly formed accretion disk (somewhat like the accretion disk that formed our planets?).

2. I don&#39;t buy that the explosion was symmetric. More likely the iron (ferrics) dominates the spectrum from the &#39;polar&#39; material ejected axially, but not in the ring, because

a.) The axial explosion completely mixed iron (ferrics) into the small amounts of organics and silicates in that direction.

b.) The ring retained chemical heterogeneities from the parent star.

With kind regards,

Oliver
http://www.umr.edu/~om

cran
2005-Aug-22, 06:26 PM
Hi Oliver,
yes, you said it better :D

om@umr.edu
2005-Aug-23, 04:36 AM
Hi, Cran.

Do you think an axial supernova explosion might leave isotopes made by different nuclear reactions in the parent star (e.g., He-burning, r-process, s-process, p-process, e-process) unmixed, like the "unmixed clumps of organics and silicates and iron (ferrics) in the newly formed accretion disk"?

With kind regards,

Oliver
http://www.umr.edu/~om

cran
2005-Aug-23, 06:08 AM
Oliver, hi... :)

I think you have me confused with a smart person... :blink:

I begin by saying I have little to no idea about the interactions (turbulence, vertical convection cells, latitudinal plasma streams, or otherwise), flow regimes, and possible mixing zones within a star, especially a star of sufficient mass to lead to a supernova - I&#39;m not all that thrilled with the differentiated layering I&#39;ve seen in some descriptive diagrams - but I understand that these were exceedingly simplified... <_<

So, if an axial (that was the term I was scratching for&#33;) supernova explosion was really that (and not an artifice of observation/measurement), then I would have to imagine that the controlling mechanism for release is analogous to that of other polar jets (ie, related to or influenced by magnetic or rotational controls) ... this should encourage some mixing during the release, but I would not consider it homogenous nor isotropic at any level of scale ... nor am I really comfortable with the concept that the heavier elements will be released and remain as individual ions in an expanding cloud ... turbulence leading to thermal and density gradients should encourage aggregation of elements into affinity groups (even if no other sorting or clumping occurs) as seems to be the case with CAIs and other silicates and organics (I recently read somewhere about some &#39;presolar&#39; and immediately post-supernova (ie within 2 million years) dates for meteoritic CAIs and olivines)... :blink:

So, I think my answer is &#39;yes&#39;; but it would be &#39;yes&#39; even if it were not an axial explosion... the idea of a smoothly expanding sphere of horizontally differentiated ionic particles and electrons would imply (or require?) that all flow is laminar (ie, no turbulence) and that all elements respond equally to the environment (ie, all particles proceed in standard vectors without influencing nor being influenced by the mass of surrounding particles and/or the medium traversed) neither of these conditions fit any observation or experiment of which I am aware... so I&#39;m comfortable with the idea that expelled matter will first be influenced by turbulence to aggregate (rather quickly) into affinity groups of similar masses and PT responses, and the overall geometry and population density will be influenced by the surrounding environment... :blink:

Well, that was my starting point for AIT (accretion in transit), to get away from the smooth homogenous isotropic slowly rotating collapsing presolar nebula that needed &#39;sticky&#39; dust to start accreting ... and the &#39;sticky&#39; dust seemed to know just which elements to pack together in just the right ratios to get the minerals and compounds that built the rocks that... etc. :rolleyes:


Does that make any sense? :unsure:

om@umr.edu
2005-Aug-23, 11:40 AM
Hi, Cran.

Let me begin with a quote, "To know that you do not know is best. To pretend to know what you do not know is a disease."

You are "a smart person" precisely because you do not assume so.

The less smart live in fear that others will discover the secret they themselves publicly announce everytime they call someone else a "crackpot".

Your "AIT (accretion in transit)" concept seems to be exactly what is needed to explain the links observed between chemical and isotope variations in meteorites and planets that exactly match those expected in supernova debris.

That issue has been hotly debated in the scientific literature since 1975, with the majority naming the observations, e.g., FUN anomalies, Ne(A.), Ne(B.), Ne(C.), Ne(D.), etc. or suggesting that it is impossible for SN debris to form planetary solids, instead of offering an explanation for the observations.

You seem to be exactly the kind of person needed in science now.

With kind regards,

Oliver
http://www.umr.edu/~om

cran
2005-Aug-23, 04:41 PM
Thank you, Oliver...
I&#39;ve always enjoyed finding the questions... and then seeing what answers might fit, preferably without the need for applying new &#39;laws&#39; or &#39;realities&#39;.
When I submitted my 2001 essays (which included a brief description of AIT), I suggested that "... the evolution of a branch of science, such as cosmology, is the result of many branches of study contributing the means to tackle the core questions.
"Cosmology begins with the disciplines of Philosophy (exemplified by, but not restricted to, the ancient Greeks) and naked-eye astronomy (principally for navigation and chronometry). Advances came through geometry (such as Eratosthene&#39;s demonstration of the curvature of the Earth&#39;s surface, and from that a close approximation to the size of the planet) and engineering (such as the construction of astronomical observatories and equipment, most especially the telescope), and mathematics and physics (such as Newton and Einstein and Hawking), and chemistry (such as Mendeleyev) without which, spectroscopy would have been nothing more than an explanation for rainbows, and biology (such as Pasteur and Darwin and Avery), and most recently planetary geology.
"Is that the end of it? No. Is there room, or need, for any other branches of science to contribute? Most certainly. One might &#39;predict&#39; that the next major contribution to our understanding of the universe and our place in it will come from disciplines which most understand the properties of large- and small-scale fluid interactions, of currents and density differences, of how discrete particles behave in waves and turbulence, and of how all these things come together in a total complex system; in short, from oceanography and meteorology."
And by sharing ideas, and taking any new (for me) findings on board... I have learned so much more than if I had simply made up my own mind, and shut out any others.
With all of the &#39;eyes&#39; and instruments we have searching the universe, from the very small to the very large... the picture gets stronger and clearer... and I have felt very chuffed whenever a new discovery has been announced that neatly fits the mental jigsaw puzzle I&#39;ve been building over the last 30 years or so... very few times, have I had to knock down part of my own design and reconfigure it to accomodate some finding... it is a most fantastic time to be alive and wondering about the universe&#33;
Now... if I can only get a better handle on the maths and the Greek alphabet... I might be able to convey concepts more accurately and clearly... :blink:
That is why I may always be an undergrad science student, and not someone with &#39;PhD (Geol)&#39; after his name... :(
But it doesn&#39;t stop me asking questions, and offering answers... :D

om@umr.edu
2005-Aug-23, 06:56 PM
Sorry, Cran

I replied, but somebody eliminated my posting.

Anyway, hang in there, my friend. You are on the right track&#33;

With kind regards,

Oliver
http://www.umr.edu/~om

cran
2005-Aug-23, 07:20 PM
The meaning of life and the search for truth (or God if one is so inclined) seem indistinguishable to me. And to me, Oliver, and to me...
at the risk of running &#39;off-topic&#39;, I was pleased that my first year supervisor, Dr Craig Simmons, at Flinders University began his very first lecture with...
"QUESTION EVERYTHING&#33;"
Frightened the hell out of most of the young ones, but I knew right then, I was in the right place at the right time... :D

And with Hubble, Chandra, ion microprobes, and all of the best equipment we can bring to bear on &#39;the great out there&#39;, we really are putting together a workable explanation for our evolution ... we are indeed &#39;stardust&#39; ... and a natural result of an increasingly apparent common set of circumstances ... massive stars with short (10^7) main sequences ... stupendous turbulent clouds of raw materials ... E=mc^2 and the intrinsic relationship of space-time-gravity ... how arrogant and parochial it must seem to believe that we are unique to this universe ... how frustrating to have to wait for generational change ... for understanding and then acceptance to catch up with evidence ... for the mind capable of translating our interpretations into the universal language of mathematics ... and for the will to push against the inertia of traditional comfort zones.

Being able to study events like SN1987A in &#39;real time&#39; (+140,000 years) is a treasure beyond counting&#33; I hope I never lose my inner child - always eager for the next new discovery; always asking the questions ... I know I must grow old, I am determined never to &#39;grow up&#39;&#33; :lol:

Guest
2005-Aug-23, 08:01 PM
Originally posted by cran@Aug 23 2005, 07:20 PM

The meaning of life and the search for truth (or God if one is so inclined) seem indistinguishable to me. And to me, Oliver, and to me... at the risk of running &#39;off-topic&#39;, I was pleased that my first year supervisor, Dr Craig Simmons, at Flinders University began his very first lecture with...
"QUESTION EVERYTHING&#33;"
Frightened the hell out of most of the young ones, but I knew right then, I was in the right place at the right time... :D

And with Hubble, Chandra, ion microprobes, and all of the best equipment we can bring to bear on &#39;the great out there&#39;, we really are putting together a workable explanation for our evolution ... we are indeed &#39;stardust&#39; ... and a natural result of an increasingly apparent common set of circumstances ... massive stars with short (10^7) main sequences ... stupendous turbulent clouds of raw materials ... E=mc^2 and the intrinsic relationship of space-time-gravity ... how arrogant and parochial it must seem to believe that we are unique to this universe ... how frustrating to have to wait for generational change ... for understanding and then acceptance to catch up with evidence ... for the mind capable of translating our interpretations into the universal language of mathematics ... and for the will to push against the inertia of traditional comfort zones.

Being able to study events like SN1987A in &#39;real time&#39; (+140,000 years) is a treasure beyond counting&#33; I hope I never lose my inner child - always eager for the next new discovery; always asking the questions ... I know I must grow old, I am determined never to &#39;grow up&#39;&#33; :lol:
It sounds like Dr Craig Simmons was a wise teacher.

We are indeed fortunate, Cran, to live in these exciting times. Yes, we will all grow old, but what better way is there to spend our allotted time than trying to decipher the new findings from

"Hubble, Chandra, ion microprobes, and all of the best equipment we can bring to bear on &#39;the great out there&#39; " ?

Life is a great&#33;

With kind regards,

Oliver
http://www.umr.edu/~om

cran
2005-Aug-23, 08:37 PM
We are indeed fortunate, Cran, to live in these exciting times. Yes, we will all grow old, but what better way is there to spend our allotted time than trying to decipher the new findings from "Hubble, Chandra, ion microprobes, and all of the best equipment we can bring to bear on &#39;the great out there&#39; " ? None at all, Oliver... :D
...unless someone wants to offer me a seat on the first starship heading out there to study one up close, of course...&#33; :lol:

om@umr.edu
2005-Aug-23, 11:55 PM
Hi, Cran.

Starship travel is not required&#33;

There is a star nearby on which we have many puzzling observations, including two that Nobel Laureate William A. Fowler identified as "problems in the most basic concepts".

Since old Sol is the model for other stars in the cosmos, there is no need to waste time in travel. Let&#39;s decipher this one first and then perhaps we will better understand the signals from distant objects.

With kind regards,

Oliver
http://www.umr.edu/~om

cran
2005-Aug-24, 12:14 AM
>sigh< Oliver, you are right, of course :)
... but the thought of flying off to an impending supernova and capturing some &#39;before&#39; and &#39;after&#39; specimens... >sigh< :D

Guest
2005-Aug-24, 03:30 PM
Hi, Cran.

"The grass always looks greener on the other side of the fence", as the cow claimed, but the iron-rich ball of dirt beneath your feet is your "after" specimen.

So far as I know nobody doubts that the equilibrium process (e-process) near the center of a supernova made the iron isotopes that now comprise about 40% of Earth, the material on which you now stand &#33;

Hester et al. of Arizona State University recently announced that the early solar system also had live Fe-60 from the core of a supernova &#33;

If you want a closer view of the "after", you might move to Mercury. It&#39;s a little warmer there, but elements from the core region of a supernova would then comprise about 60% of the material beneath your feet &#33;

Instead of "flying off to an impending supernova", Cran, you need to get out your shovel and start digging.

Best wishes,

Oliver
http://www.umr.edu/~om

cran
2005-Aug-24, 06:08 PM
Instead of "flying off to an impending supernova", Cran, you need to get out your shovel and start digging.
Yes, but... I want it all&#33; :D
I want to see the changes that occur inside a star...
I want to sample the ejected material...
I want to see the explosions...
I want to capture bits of the raw stuff...
before it has cooled...
before it has accreted...
before it is further altered by nuclear decay...
before it is differentiated...
I want to see that instant when chemistry
becomes biology...
I want to see if the first oceans are liquid
or supercritical fluid...
I want to see a collection of silicates, organics, and ices
accumulate until that critical mass is achieved
and the protoplanet begins to gorge itself
on hydrogen and helium...
I want to sample the surrounding material
just before and just after
a new star bursts into glorious light
and watch the growing bubble of its influence
and ride the wave of its first wind
I want to see and to feel
the flow of energies
the dance of vortices
the wondrous parade of evolution&#39;s possibilities
because that&#39;s what I am...
amateur scientist... professional dreamer :lol:
and yes, I do dig into the dirt...
and I watch the drill and touch the cores
and marvel at the colours and patterns within
and I watch the needle tremor
and try to picture the flow of partial melt
and revel in every new detail that emerges
about the dynamics within the mantle
the shape and structure of the core
and the endless slow dance of its crystals
even as I struggle to follow the water
from air to soil to rock to river to sea
how it flows and how it changes
the character of what it flows through
and over... and under
how it freezes and melts and vaporises
how it takes a mountain
and makes it a molehill
and wherever I have followed water
here there be life&#33;
in forms and fashions beyond counting
from too small to see
to too big to see in its entirety
complex interacting amazing ecosystems
in a single drop of water
or in world-girdling biosphere
I want to see it all&#33;
Even if I understand none&#33;
:)

om@umr.edu
2005-Aug-24, 06:16 PM
Then, Cran, I recommend that you start by learning about stable isotope mass spectrometry.

In spite of the big words and the "bamboozle" usually associated with such, isotopes have in fact retained a record of many of these events.

It is the closest thing to time travel available.

Best wishes,

Oliver
http://www.umr.edu/~om

Duane
2005-Aug-24, 10:18 PM
Hester et al. of Arizona State University recently announced that the early solar system also had live Fe-60 from the core of a supernova &#33;

A deliberate misquote. Hester et al conclude the Fe60 came from a supernova or supernovas after the solar system had already formed.

Nice try Oliver.

om@umr.edu
2005-Aug-24, 11:41 PM
Originally posted by Duane@Aug 24 2005, 10:18 PM

Hester et al. of Arizona State University recently announced that the early solar system also had live Fe-60 from the core of a supernova &#33;

A deliberate misquote. Hester et al conclude the Fe60 came from a supernova or supernovas after the solar system had already formed.

Nice try Oliver.
Sorry, Duane.

But you are mis-informed again.

The Science article concerned The Cradle of the Solar System, where the solar system formed.

With kind regards,

Oliver
http://www.umr.edu/~om

Duane
2005-Aug-25, 01:06 AM
Originally posted by om@umr.edu @Aug 24 2005@ 04:41 PM
But you are mis-informed again.

Oh really. Quotes from the article:


Rather, like most low-mass stars (4), the Sun formed in a high-mass star–forming region where one or more stars went supernova. Credit: 21 MAY 2004 VOL 304 SCIENCE


Low-mass stars that form around an HII region should pass through a well-defined sequence: (i) A shock driven in advance of an ionization front compresses molecular gas around the periphery of an HII region, compressing dense cores and causing them to become unstable to gravitational collapse (6). (ii) These cores are overrun by the advancing ionization front within ~105 years. As cores emerge into the HII region interior, they go through a short-lived (~104 year) phase during which the dense core itself photoevaporates. This is* the “evaporating gaseous globule” or EGG phase best seen in Hubble Space Telescope (HST) images of the Eagle Nebula (7). (iii) EGGs that do not contain stars are dispersed, but when a star-bearing EGG evaporates, the circumstellar disk inside is exposed directly to UV radiation from the massive stars. The object transitions into an “evaporating disk” phase, best seen in HST images of “proplyds” in the Orion Nebula (8). (iv) The evaporating disk phase is also
short-lived (9). Within a few tens of thousands of years, photoevaporation erodes
the gaseous disk to within a few tens of astronomical units of the central young stellar object (YSO) (10). (v) The young star and its truncated disk then reside within the ionized, low-density interior of the HII region for the remainder of the few million-year lifetime of the region. This is the environment in which planetary systems such as our own form. (vi) When the massive stars exciting the region go through a high mass-loss “Wolf-Rayet” phase and/or go supernova, the protoplanetary disks surrounding nearby low-mass YSOs are pelted with ejecta. Such events are responsible for the short-lived radionuclides found in meteorites in our own solar system. Credit: 21 MAY 2004 VOL 304 SCIENCE Emphasis added by Duane

As I said, yours is a misquote.

cran
2005-Aug-28, 04:15 PM
Well, while I don&#39;t know all the proper names for these things, Duane, your quoted summary seems to gel very well with what I understand our solar system&#39;s formative history to be... as refined over time with new observations and findings... :D

>thinks< "...a high mass-loss “Wolf-Rayet” phase..." must remember that... ;)