Starship Asterisk*

[quote="fastartceetoo"]say that a small asteroid has been spotted some distance from Earth, but its trajectory has not yet been determined. It would be quite correct, then, to state, "the odds of it impacting in your back yard are very very low".[/quote]I dont see how errors in our observations/measurements translate into probabilities for event.

hello
fastartceetoo

Your right,,,,,,,,,,,the only problem we have is that we need more info.

Until than your opinion is just as good as others.

I agree with you with the line axis,,,,,,,,,,,,,,,,you have a very good point.

[quote="makc"][quote="fastartceetoo"]If we were considering all nova & supernova, maybe. But we are talking here about just one particular supernova, so the odds... are very very low.[/quote]But we do talk about "all nova & supernova", "odds" do not exist at all for "just one particular supernova".

You would see similar echo pattern around most of exploded stars, were "the odds" better, BUT it is BECAUSE "the odds are very very low" you see it only with this "one particular supernova" out of all of them.[/quote]

Hi again, makc,

Not to quibble (too much ;-) ), but you *can* speak of 'odds' for single events. For example, say that a small asteroid has been spotted some distance from Earth, but its trajectory has not yet been determined. It would be quite correct, then, to state, "the odds of it impacting in your back yard are very very low".

But back to the main issue, the target pattern around SN 1987A.... I think two different phenomenon are being discussed in this thread:

-- there is an hour-glass shaped phenomenon that is evident in a different set of rings that have been well documented. These rings are somehow created by the shock waves from the supernova. They do not appear to us as concentric rings (and they are elliptical in shape) because the axis of this hour-glass shape does not point toward Earth. An image of these rings can be seen at:
http://csep10.phys.utk.edu/guidry/violence/sn87a.html

-- then there are the 'light echo' rings that form the 'target' pattern. I was referring to *this* set of rings when I asked if they might be caused by light from the supernova progressively illuminating pre-existing spheres of debris that were shed by the star long before the supernova occurred.

Thanks to all for replies.

[quote="fastartceetoo"]If we were considering all nova & supernova, maybe. But we are talking here about just one particular supernova, so the odds... are very very low.[/quote]But we do talk about "all nova & supernova", "odds" do not exist at all for "just one particular supernova".

You would see similar echo pattern around most of exploded stars, were "the odds" better, BUT it is BECAUSE "the odds are very very low" you see it only with this "one particular supernova" out of all of them.

I think they are using the Hubble telescope to make more observation.

maybe later with more info we maybe able to say more.

Bu! do not close doors on options until the cow comes home.

[quote="makc"][quote="fastartceetoo"]I don't think the 'hourglass' explanation works. Yes, it can result in multiple circles, but in order for such circles to appear in a 'target' pattern, the axis of the hourglass would have to be pointing directly at the earth ...which is extremely unlikely.[/quote]why? it's really big universe. so that number_of_stars x small_probability could be very well more than 1.[/quote]

Hi makc,

If we were considering all nova & supernova, maybe. But we are talking here about just one particular supernova, so the odds that the axis of an hourglass formation around SN 1987A would point directly at Earth are very very low.

There's got to be some other explanation.

Art

The options could be many.

I say one option being the hour glass which is quite normal. Facing us like a bulls eye is not so rare. There are many examples

can someone bring another option to the table.

All ears
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edit
see link
http://antwrp.gsfc.nasa.gov/apod/ap970124.html
quote"When observed by the Hubble Space Telescope (HST) in 1994, large strange rings were discovered whose origin is still mysterious, although thought to have been expelled even before the main explosion"

and link

http://hubblesite.org/newscenter/newsdesk/archive/releases/1997/03/

This link confirms my previous posting of the hour glass.

[quote="fastartceetoo"]I don't think the 'hourglass' explanation works. Yes, it can result in multiple circles, but in order for such circles to appear in a 'target' pattern, the axis of the hourglass would have to be pointing directly at the earth ...which is extremely unlikely.[/quote]why? it's really big universe. so that number_of_stars x small_probability could be very well more than 1.

I don't think the 'hourglass' explanation works. Yes, it can result in multiple circles, but in order for such circles to appear in a 'target' pattern, the axis of the hourglass would have to be pointing directly at the earth ...which is extremely unlikely.

And the other posited explanation -- back scatter and re-scatter -- would produce a haze, not a target pattern.

Come on... there has to be a professional astronomer out there who knows the exact cause of this phenomenon. I still think that it is supernova light illuminating old planetary nebulae.

Goodhaddow your comments are OK.

as for the rings
see link

http://antwrp.gsfc.nasa.gov/apod/ap970124.html

there are many other links of similar hour glass if you snoop around,,,,,,,,,smile

http://antwrp.gsfc.nasa.gov/apod/ap971023.html

http://www.spacetelescope.org/

look for hour glass images just before the star explodes, notice the gravitational electromagnetic shape created by the inner core of the sun.
This is the main cause of the rings

If the light is reflected from a minute particle, it is reflected in multiple directions, including directly back where it came from, so it is going to be reflected again from the particles it missed the first time by.
Gord

Fastartceeto0

Maybe you are right.

Thanks for all the links, Harry... I looked at each and every one.

A single (not a binary or a triple) star's planetary nebula is roughly spherical. I'm wondering if this star went through several cycles of casting off its outer layers, forming a set of nested spheres. Then, when it went supernova, the light burst, as it expanded, illuminated the already-existing nebulae ...which we see as a set of circles.

before a star explodes it will form an hour glass object and after you may get multiple explsions.

This maybe causing the rings

see links

http://antwrp.gsfc.nasa.gov/apod/ap970124.html
http://antwrp.gsfc.nasa.gov/apod/ap971023.html
http://antwrp.gsfc.nasa.gov/apod/ap971024.html
http://www.aao.gov.au/images/general/supernova_frames.html
http://hyperphysics.phy-astr.gsu.edu/hbase/astro/snovcn.html#c3
http://antwrp.gsfc.nasa.gov/apod/ap041229.html
http://antwrp.gsfc.nasa.gov/apod/ap050204.html


http://antwrp.gsfc.nasa.gov/apod/ap041219.html

http://antwrp.gsfc.nasa.gov/apod/ap031101.html
http://antwrp.gsfc.nasa.gov/apod/ap050311.html
http://www.aao.gov.au/images/general/planetary_frames.html
http://antwrp.gsfc.nasa.gov/apod/ap051124.html

http://antwrp.gsfc.nasa.gov/apod/ap031207.html

But ! there is much more

this is indeed caused by the light being reflected off dust and gas present around the star which is not uniformly distributed, whether this gas and dust has been ejected from the same star is debatable

Hi Wolf,

Thanks for the reply... but no 'cold one' yet! If you project a sphere of some thickness (like a bubble with a thick membrane) on a plane, you would get a ring, most dense at the 'edge' of the sphere (as we see it), and less dense as you move toward the center, with the lowest density at the center.

I don't at all see how a projected sphere yields multiple rings unless you are talking about interference patterns... which isn't the case here.

My conjecture, now, is that the light front from the supernova has illuminated several planetary nebulae rings -- previously not observable -- which were ejected by the star at very long intervals in the past.

When you project a three dimensional object ( a sphere ) onto a two dimensional photographic plate, you get rings...........pass the ice cold one :D

I don't understand the 'target' appearance of the reflecting light echos. Why doesn't the reflecting echo appear as a *single* expanding ring?