The life cycle of StarsThe life cycle of Stars

Where do stars formWhere do stars form

Stars form in clouds of gas (a nebula)Stars form in clouds of gas (a nebula) These are called diffuse nebula or These are called diffuse nebula or

star forming nebula.star forming nebula. A single nebula can form hundreds or A single nebula can form hundreds or

even thousands of starseven thousands of stars Let’s see what they look like!!Let’s see what they look like!!

M8 – The Lagoon Nebula M16 – The Eagle Nebula

Star Forming RegionsStar Forming Regions

M17 and M20M17 and M20

What happens when What happens when stars start forming in stars start forming in nebulasnebulas Stars often form in groups called “clusters”Stars often form in groups called “clusters” There are two types of clustersThere are two types of clusters

1. open clusters usually have only a 1. open clusters usually have only a few few hundred stars and are found hundred stars and are found inside inside galaxiesgalaxies

2. globular clusters have hundreds of 2. globular clusters have hundreds of thousands of starsthousands of stars

Open cluster - M45Open cluster - M45

The Pleiades – The Seven Sisters

Globular clustersGlobular clustersM13 and M15M13 and M15

These globular clusters can These globular clusters can be very densely packedbe very densely packed

What happens at the end What happens at the end of the stars life?of the stars life?

Average stars produce planetary nebulaAverage stars produce planetary nebula When the core of the star starts a fusion When the core of the star starts a fusion

reaction with the helium ash, the temperature reaction with the helium ash, the temperature increases dramatically causing the outer layers increases dramatically causing the outer layers to be puffed off.to be puffed off.

Big stars produce supernova explosionsBig stars produce supernova explosions When larger stars start to produce iron at their When larger stars start to produce iron at their

core, it marks the beginning of the end. The core, it marks the beginning of the end. The core collapses and then rebounds in a massive core collapses and then rebounds in a massive explosion called a supernova!explosion called a supernova!

A glimpse at our A glimpse at our futurefuture

M27 – The dumbell Nebula M57 – The ring Nebula

More PlanetariesMore Planetaries

M97 - The owl nebulaM97 - The owl nebula NGC 7293 – The Helix Nebula

What about supernovasWhat about supernovas

This star is in thelarge Magellaniccloud and becamevisible to the nakedeye in 1987 but it actually explodedabout 180,000 yearsago

How do we anything How do we anything about stars?about stars?

From their spectrumFrom their spectrum We know the composition of the atmosphereWe know the composition of the atmosphere We know how fast the object is movingWe know how fast the object is moving We know the strength of its magnetic fieldWe know the strength of its magnetic field

How do we know the How do we know the temperaturetemperature

By looking at the colorBy looking at the color

RED = 2000 degreesRED = 2000 degreesYellow = 6000 degreesYellow = 6000 degreesBlue = up to 100,000 degreesBlue = up to 100,000 degrees

How did we figure the life How did we figure the life cycle of stars?cycle of stars?

We use an HR diagramWe use an HR diagram The HR diagram compares temperature The HR diagram compares temperature

to brightnessto brightness