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Author Topic:   Falsifying a young Universe. (re: Supernova 1987A)
Sylas
Member (Idle past 5250 days)
Posts: 766
From: Newcastle, Australia
Joined: 11-17-2002


Message 272 of 948 (194906)
03-28-2005 6:37 AM
Reply to: Message 271 by peaceharris
03-28-2005 5:38 AM


Re: The Math of the Matter?
The claim that the ring around sn1987a was formed before the star exploded has zero evidence.
That is incorrect.
The explosion was seen in 1987. The rings were first seen a few years later, as soon as Hubble was operational and able to get clear pictures. If the rings were formed in the explosion, the expansion rate would be easily detectable in the 15 years or so since. No such expansion of the ring has been seen; which proves that they were in place well before the explosion.
In fact, the speed of expansion of the rings was inferred from the spectral analysis of the light echo from the explosion, and found to be about 10 km/sec on the inner ring. Its size is 0.6 ly in radius, so it had been expanding for about 20,000 years prior to the explosion. This also is consistent with the rings remaining at the same size.
The speed of the ejecta from the explosion was also able to be found by spectral analysis, and based on this, and the size of the ring, a prediction was made in 1994 (Luo and McCray) that ejecta from the explosion would be seen to collide with the outer rings about 9 to 15 years after the explosion; in 1999 +/- 3 years. This prediction was spectacularly confirmed, as the rings have been lighting up from this predicted collision. This also is proof that the rings were in place well before the explosion and of the measured size.
SN1987A is the most carefully studied supernova ever. The evidence is unambiguous about distance and size and velocity of the material involved.
Cheers -- Sylas

This message is a reply to:
 Message 271 by peaceharris, posted 03-28-2005 5:38 AM peaceharris has replied

Replies to this message:
 Message 274 by peaceharris, posted 03-28-2005 7:49 PM Sylas has replied

  
Sylas
Member (Idle past 5250 days)
Posts: 766
From: Newcastle, Australia
Joined: 11-17-2002


Message 280 of 948 (195119)
03-29-2005 2:30 AM
Reply to: Message 274 by peaceharris
03-28-2005 7:49 PM


Re: The Math of the Matter?
The expansion rate of the ring would be detected easily if it continued to expand at velocities more than 1000km/s. But the ring expands at such high velocities only for the first few months, after that the expansion velocity decreases. This has been observed for nova cygni 1992. (refer table 3 of AJ Vol 121, pg 1636).
The model peaceharris requires is physically ludicrous, and nothing like what was observed with cygni 1992. Peaceharris requires the SN1987a ring to pretty much stop dead after 3 months; because we detect no expansion in the apparent size of the ring at all over the last 15 years. In the model used by scientists, on the other hand, the ring has been expanding for 20,000 years, and so the apparent motion is expected to be negligible.
The rings mostly likely are slowing due to interactions with the ISM (though they are now being torn apart). In the same way, the Cygni 1992 rings are still moving. Making the SN1987A rings as fairly nearby would require that the rings have stopped dead. This is inconsistent with behaviour of Cygni 1992, physically nonsensical, and in conflict with all available evidence of SN1987A.
peaceharris writes:
Harris: The calculations of Luo, McCray and Slavin (ApJ Vol 430, pg 264) predict that a "A bright arc will suddenly appear at the near side of the ring and grow into an entire ring about 11 months later."
A tilted circular ring would look like an ellipse to us. The nearest and farthest side is along the minor axis of the ellipse. Could you show me a picture of the ring with a bright spot at the minor axis? 5.5 months later, half of the ellipse should be bright and the other half dark. The boundary separating these would be the major axis. Could you please tell me where I can find this photo? Please do tell me when exactly the bright arc appeared. I would like to compare the images taken on this date with an image taken 11 months later.
These images are famous. Dick McCray has an excellent on-line book. See Lesson 6, on supernovae; and section 6 on SN1987A. This includes a series of 15 images of the collisions of the explosion ejecta with the ring around SN1987a, taken from Sept 24 1994 to Nov 28 2003. Note that there is a small star at 5 o'clock in the images, which looks like a hot spot in the ring. You should ignore this; it has nothing to do with the collision.
Bear in mind that the ring is not moving in perfect lock step. It has been moving 20,000 years, and it has a small but noticable lumpiness. There are regions with lumps of gas just a bit closer to the main central star; these are the first to collide with the expanding supernova remnant. The ejecta is also not all moving at the exact same speed, and some parts of the ejecta will arrive at the ring a bit before the main bulk of material. This means that the ring does simply all light up at the exact same instant. There are a series of hot spots from clumpiness of the ring, and illumination of the ring will grow and fade again over about seven years. Since first illumination was around 2000 to 2002, we can expect the main show to until 2009 or thereabouts.
This collision is with the smaller inner ring. The ring is 0.6 light years in diameter, and because of the angle, light from one end of the minor axis takes an additional length of time to reach us of about 11 months. You can see in the images that the upper part of the ring tends to light first, so this is probably the part that has the smaller light travel distance. Since the ring has thickness and since the ejecta is a bit spread out, the collision at any point is a gradual brightening over time, and it starts at a series of hot spots where the ring has material that is closest to the central star. You can never get a simple dark semi circle, nor should this be expected.
In 1999 the first spot appears, then in 2000 the first spots on the further side. we start to see more collision spots appearing around the ring. In 2003 the whole ring is a blaze of light. The sequence can also be viewed as a movie.
Finally, note that peaceharris wants this supernova to be less than 5000 light years away. This is actually less than the distance to cygni 1992! As has been noted, peaceharris's notion is immediately seen to be invalid just by density and luminosity of stars. It has no merits whatsoever.
Cheers -- Sylas
This message has been edited by Sylas, 03-29-2005 03:54 AM

This message is a reply to:
 Message 274 by peaceharris, posted 03-28-2005 7:49 PM peaceharris has replied

Replies to this message:
 Message 281 by peaceharris, posted 03-29-2005 5:22 AM Sylas has replied

  
Sylas
Member (Idle past 5250 days)
Posts: 766
From: Newcastle, Australia
Joined: 11-17-2002


Message 282 of 948 (195131)
03-29-2005 6:32 AM
Reply to: Message 281 by peaceharris
03-29-2005 5:22 AM


Re: The Math of the Matter?
The first spot (at position angle 31 degrees) appeared in 1997. Refer ApJ Vol 492, L 139.
Yeah... but this hardly shows up in the images. You can just make it out, if you look. I was not being technical, but commenting on what shows fairly clearly in the photos. This first spot seems to be a lump well inside the main bulk of the ring; you can even see a slight prominence in the photos. The main ring does not really get going until later. But yes, you are right; the first signals of the collision were detected in 1997.
Could you explain how you come to this conclusion. I do not believe that the ring stopped expanding after 3 months.
The ring has subtended the same arc in the sky for the last 15 years; yet it grew to that size in three years according to peaceharris's notions. Stars don't do that. Any expansion rapid enough to make the ring in three years would still be proceeding at a rate to see some difference in the next fifteen. But we don't.
On the other hand, we have timed the material in the ejecta now colliding with the ring, using Lyman alpha lines. It is moving at 15,000 km/sec. This is another confirmation of the ring size being 0.6 light years in radius.
Cheers -- Sylas
This message has been edited by Sylas, 03-29-2005 06:40 AM

This message is a reply to:
 Message 281 by peaceharris, posted 03-29-2005 5:22 AM peaceharris has replied

Replies to this message:
 Message 290 by peaceharris, posted 03-29-2005 9:15 PM Sylas has not replied

  
Sylas
Member (Idle past 5250 days)
Posts: 766
From: Newcastle, Australia
Joined: 11-17-2002


Message 284 of 948 (195140)
03-29-2005 8:04 AM
Reply to: Message 283 by RAZD
03-29-2005 7:14 AM


How the ring should appear when lit
RAZD writes:
I am saying you are wrong in your use of an ellipse with a major and minor axis and the illumination occuring on the minor axis first.
Actually, this bit is pretty much correct.
He is not saying it "is" an ellipse. The form of the ring is an elipse because the circle is at an angle of about 43 degrees to our line of sight. He is also correct that we should expect one end of the minor axis to light up first, and the other end to light up last.
The major axis is pependicular to us, and the minor axis is a line at an angle of 43 degrees, so it appears 70% shorter and gives the ring its elliptical shape in the sky. One end of the the minor axis is the closest point to us; the other is the most distant. The whole ring lights up at the same instant in proper time; but we see the closer end of the minor axis first, and most distant end last, becuse of the time difference for the light to get here.
If it was a perfect circle, and if all the ejecta traveled at the same speed, then we would indeed have the ring light up in the sky starting at one end of the minor axis, and then extending back around to the other end when the whole ring become lit.
It does not quite look like that, because there are clumps in the ring, and what gets lit first at the lagging clumps just inside the main body of the ring. So you don't get a perfect ring of fire so much as a string of beads. Even so, there is a tendency for the first beads to appear near one end of the minor axis, and for the last part of the ring to have beads of light to be at the other end of the minor axis, 11 months later.
11 months is cos(43 degrees) * 12 months * 1.2 light years diameter.
Cheers -- Sylas

This message is a reply to:
 Message 283 by RAZD, posted 03-29-2005 7:14 AM RAZD has replied

Replies to this message:
 Message 285 by RAZD, posted 03-29-2005 8:09 AM Sylas has not replied

  
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