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 IceInSpace Supernovae Type 1a Distance Modulus
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#1
28-08-2017, 05:32 AM
 RetEng Registered User Join Date: Aug 2017 Posts: 2
Supernovae Type 1a Distance Modulus

On website http://web.mit.edu/8.286/www/ps05/e9p5b.html tabular data for redshift and distance moduli are given for almost 200 SN 1as, taken from an earlier paper by Adam Reiss, et al. No specific definition is given for the distance moduli provided but when the data are fed to a standard
distance-modulus-to-distance converter, the distances calculated seem wrong. e.g for SN 1997ff the table value for distance modulus is 45.53
Using a converter formula
10 to the power of (((distance modulus -25)/5))
the calculated distance is 12764 mpc or 41.6 billion light years ! Impossible ! Can anyone suggest how to calculate actual distances from the distance moduli referenced above ? My thanks in advance for a reply.
#2
30-08-2017, 11:25 AM
 Dave2042 (Dave) Registered User Join Date: Feb 2010 Location: Newtown, Sydney, Australia Posts: 164
Quote:
 Originally Posted by RetEng On website http://web.mit.edu/8.286/www/ps05/e9p5b.html tabular data for redshift and distance moduli are given for almost 200 SN 1as, taken from an earlier paper by Adam Reiss, et al. No specific definition is given for the distance moduli provided but when the data are fed to a standard distance-modulus-to-distance converter, the distances calculated seem wrong. e.g for SN 1997ff the table value for distance modulus is 45.53 Using a converter formula 10 to the power of (((distance modulus -25)/5)) the calculated distance is 12764 mpc or 41.6 billion light years ! Impossible ! Can anyone suggest how to calculate actual distances from the distance moduli referenced above ? My thanks in advance for a reply.
Not really an expert, but
1. a) I think your calculation is correct
2. b) Remember the metric expansion of space. While the light has only had ~14bn years to travel to us, the distance between us and distant objects has grown as space has expanded since. I think the resulting diameter of the observable universe is ~90bn ly as a result, which amply accommodates your result.

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