supernova rings

Paul Arveson (
Wed, 29 Apr 1998 13:28:28 -0400

>> ... on page 151 of _Supernova! - the Exploding Star
>>of 1987_ by Donald Goldsmith: "Astronomers have been quick to make
>>mathematical models of the situation that gives rise to the light
>>echoes. Their calculations show that the inner ring arises from dust
>>located about 400 light-years from SN1987A, and the outer ring from dust
>>grains some 1,000 light-years from the supernova, all still well within
>>the Large Magellanic Cloud."

>Date: Tue, 28 Apr 1998 23:52:31 -0600
>From: Bill Payne <>

Have you found anything
>to reconcile the ring-diameter discrepancies?


A picture from the Hubble telescope in 1994 is described at

A more recent picture from Feb. 1998 is described at

These captions (also see the pictures) indicate that the rings
were formed from gas shed by the star thousands of years before
it exploded in a supernova. The rings are now several
thousands of light years in radius. Light from the supernova explosion
lit up the dust in the rings, although the rings are now
fading because the central source is fading. The pictures show

The shedding of outer layers is a predicted phenomenon for
some stars, although usually they are not seen because they
are too far away, in other galaxies. Lots of additional
details are given at the web site and in standard textbooks.
There are some questions regarding this supernova, but issues
regarding its distance, the speed of light and relativity are
not among them.

Paul Arveson, Code 724, Research Physicist, Signatures Directorate
Naval Surface Warfare Center, Carderock Division
9500 MacArthur Blvd., West Bethesda, MD 20817-5700
(301) 227-3831 (301) 227-4511 (FAX)