# HR Diagram of Star Clusters

In this exercise we will plot 3 HR diagrams of 3 star clusters. From the graphs we will be able to answer these three questions: (1) Rank the cluster from youngest to oldest, (2) Rank the cluster from closest to farthest, and (3) for each cluster, count/classify how many stars are main sequence, giant, and white dwarf. See below for the data to graph:

Read the lab “lab-HRDiagram.pdf”. You can find this in our lab package under “Syllabus”. Basically you need to plot the HR-Diagram for three clusters and answers the three questions above. You can plotting these three clusters by hand using this graph:

However plotting using Jupyter/Colab notebook will earn more credit. See Colab guidance below:

Next Watch Python Essential Training section and write a ~ 1 page review on sections 7 & 8 .

Finally answer this math question (2 points) : We observed the light from the start with wavelength λ’ = 656 nm. We know that in our lab this light has a wavelength of λo = 656.3 nm. Find the velocity of the star using the formula for Doppler shift of light in term of wavelength. See the formula in the link below

λ’ (light we see from star) = 656 nm

λo (same light we see from lab) = 656.3 nm

Co = speed of light = 3.0*10^8 m/s

Is the start moving toward or away from us?