Absolute brightness and distance.

Typical Energy outputs :
Sun : 3.9 x 10^33 erg/second.
SN type II : 10^47 erg/second ( ? ). ( Peak )
SN type Ia : 10^49 erg/second ( ? ). ( Peak )

Using Bolometric magnitudes and luminosities, we have the well known equations :
a). log( L/Ls ) = 0.4*( Ms - M )
b). M = m - 5*log(d) + 5
where
L = Luminosity, Ls = Sun's Luminosity, Ms = Sun's absolute magnitude ( +4.72 ), M = absolute magnitude,
m = apparent magnitude, d = distance in parsec and 1 parsec = 3.2616 light years.

SN 1999cb in Mrk 881 ( Peak ) :
M = m - 5*log(d) + 5
Using m = 15.7 and if Z = 0.02881 ( V = 8637 km/s ) gives a distance of 1.20*10^8 parsec, then
M = -19.7
=========
Compared with the sun, we have L/Ls = 5.9*10^9




Type Ia Supernovas have an unique brightness profile ( graph ) depending on their maximum absolute magnitude, M peak. Bright type Ia supernovas are slower to brighten and fade, while fainter ones do so at a faster than normal rate. It is then possible to find a supernova's M graph and use it together with m as a distance indicator deep into the universe.
ref. Sky & Telescope Jan 1996 p.27

Spectrogram of SN1999cb.

Spectrogram by Peter Garnavich and Perry Berlind 14.4.May 1999 UT. using the FAST Spectrograph on the 1.5m Tillinghast telescope at Mt.Hopkins.

The spectrum shows a deep, broad Na I absorption line ( 5860 Ångstrøm ) and iron features in the blue, which suggest that this is a type Ia supernova about a month past maximum brightness ( IAUC 7169 ).



Image file : spektrum.gif




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