The distance of supernova remnant 1987A is computed directly: the diameters of the main ring is computed from the time of propagation of light from the star to the ring, and the angular diameters of the ring are deduced from the observations.

Michael E., McCray R. et al (ApJ 593, 809 (2003)) observed in its spectrum a "Lyman forest" similar to the forests observed in the spectra of the quasars. Applying the interpretation of the Lyman forest of the quasars, the remnant is very, very far, very, very big.

Where is the error ?

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JMB

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"Stupidity gets denser in a crowd" - Old Finnish saying. [My website and My BLOG] [Nimblebrain forums]

Well, the Lyman alpha emission from this supernova remnant is not that "similar" to the Lyman alpha forest, which is a whole bunch of absorption lines at different locations in a spectrum, corresponding to absorbing hydrogen clouds at different distances, hence different redshifts. For quasars at higher redshift the number of lines in the forest is higher. In Sn 1987A, the Lyman-a emission is at a single location in the spectrum.

As the paper states, "This emission comes from hydrogen in the debris that is excited and ionized as it passes through the remnant's reverse shock." Exciting hydrogen raises the energy of its electron, which then quickly drops back to its ground state. As it drops, it releases a photon of a certain wavelength. When there are lots of such photons, they are detectable in spectra as emission lines. Specifically, Lyman-alpha relates to the photons released when the electron energy level goes from 2 back to 1, the ground state. I expect the spectral location in the referenced Lyman-a emission corresponds to the distance of Sn 1987A.

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Everyone is entitled to his own opinion, but not his own facts.

That was put poorly... or wrongly. Best just to check out that link re the Lyman Series.

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Everyone is entitled to his own opinion, but not his own facts.

As I understand it, the researchers are assuming the 'more redshifted' spectra are reflected off of, or originate in, the expansion zone moving in the opposite direction. This is a somewhat curious explanation, because reflected spectra should be badly blurred; so they have added the parametric supposition that the original event was highly unsymmetric, producing brighter spectra in preferred directions.

Although the explanations for the phenomenon may be a little weak, this is not a good example of evidence of non-doppler redshifts. There is too much uncertainty about the underlying mechanisms, and too much matter being naturally distributed at extremely high velocities.

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jwj

It's a big universe out there...is it really unwinding, really burning out?