# Doppler shift

1. May 15, 2012

### dingo_d

1. The problem statement, all variables and given/known data
Supernovae type Ia has a red shift z=1.1. Observed luminosity of the star has changed in the interval of 60 days. What time interval would an observer measure in the near vicinity of the star? What is the speed that the star is moving away from us? What is the distance of the star from us ($h\approx 0.7$)

2. Relevant equations

Red shift:

$z=\sqrt{\frac{1+\beta}{1-\beta}}-1$

$\nu_o=\sqrt{\frac{1-\beta}{1+\beta}}\nu_e$

o is for observed, and e is for emitted light.

Hubble law:

$v=H_0 d\approx 100 h d$

3. The attempt at a solution

Using the provided formulas I got:

$\beta=0.630314$
$d=2692.34 Mpc$
$T_e=28.5715 days$

Is this correct?