• You can examine the star by studying the light came from it

• Split light into its wavelength

• Measure the intensity absorbed at each wavelength

• There is specific minimum wavelength of particular star due to its atomic properties

• But minimum wavelength obtained is different,so if there difference is negative then start is moving towards the earth & if it is positive then start is moving away from the earh

#Stellar Motion

load starData
nObs = size(spectra,1)
lambdaStart = 630.02
lambdaDelta = 0.14

#Make the array of wavelength with difference of lambdaDelta

lambdaEnd = lambdaStart + (nObs-1)*lambdaDelta
lambda = (lambdaStart:lambdaDelta:lambdaEnd)

#Get the spectra of HD STAR

s = spectra(:,2)


#plot lambda VS spectra

plot(lambda,s,".-")
xlabel("Wavelength")
ylabel("Intensity")

#Find minimum intensity & its wavelength

[sHa,idx] = min(s)
lambdaHa = lambda(idx)

#Add the plot

X = lambdaHa
Y = sHa
hold on
plot(X,Y,"rs",MarkerSize=8)
hold off

#Calulate red shift factor and speed

z = (lambdaHa/656.28)-1
speed = z*299792.458**