The Colours of Stars and Planets ~ An Accurate Representation?

Today during third block, we conducted an experiment where we burnt a range of metal chlorides to see the different colours that could be produced as a result of our actions. We were presented with a range of colours from pale green to bright pink - below are the following substances we tested and the colour they produced.

     

   

Above - Lithium Chloride ~ Bright Pink

     

Above - Copper Chloride ~ Ghostly Green with a Blue Outline

   

Above - Potassium Chloride ~ Bright Red/Pink with a slight yellow flame in the middle

   

Above - Strontium Chloride ~ Bright yellow flame with a strong red outline

Was this an accurate representation of the science behind the colour of stars and planets?

I believe this was an inaccurate representation, I say this because we hadn't changed the type of the flame which then shows how each metal chloride reacted differently with the same temperature. This limits us when we want to compare our findings to actual stars and planets, when we know the colour is determined by the temperature of the planet or star.

Although we didn't change the temperature, each substance could represent matter from different stars/planets and this has allowed us to discover and compare these substances. By knowing the colour of flames as a result of burning these substances, we can compare these to as if they were a star due to the colour that was produced. By comparing these to a star, we are able to explore different colours produced by burning these substances and give them a temperature range based on their colour.

HOWEVER as we stated before we didn't actually change the temperature of the flame which then makes me wonder why these metal chlorides have different colour flames when being heated at the same temperature; e.g. strontium chloride being red/yellow and copper chloride being green/blue.

So what causes these metals salts to burn different colours? What could this mean in comparison to stars and planets? Is it just the temperature that affects the colour if so what else contributes? - These are my next questions