star temperature/life cycle

• The HR Diagram is a graph that compares the surface temperature of a star with its magnitude or how bright the would be if they were all the same distance from Earth.

• Luminosity is a term that measures how much energy leaves a star in a certain period of time.

• General Rule: As luminosity increases, brightness increases.

Temperature

Luminosity

Spectral Class

Magnitude

• Temperature: As temperature increases, luminosity increases.

• Size: As size increases, luminosity increases.

• Most Luminous? Large and Hot

• Least Luminous? Small and Cool

• All stars begin life as dust in a nebula.

• Gravity begins to form masses of hydrogen in the nebula.

• When the heat in the protostar reaches 15,000,000 C, nuclear fusion starts and a star is born!

This is the Pillars of Creation within the Eagle Nebula, part of M16, viewed by the Hubble Telescope

The mass of the star that forms in the nebula determines how the star will burn fuel:

--small stars burn their fuel more slowly and reach lower temperatures.

--large stars burn through their fuel rapidly and reach higher temperatures.

All Stars begin life as a H -> He fusing Main Sequence star.

No matter the mass of a star, as its hydrogen supply begins to run low, the core cools and the star takes on a red color, forming either a Red Supergiant or a Red Giant.

Large stars can end up as black holes or pulsars.

Small stars can end up as a Nova, Supernova or a Black Dwarf.