Evolution of Stars

Main Factor of Life Cycle Beginning mass

Nebulae Huge clouds of dust and gas

M16 – Eagle Nebula

M16 – Eagle Nebula

Stars forming in Trifid Nebula M20

½ light year long twisters in Lagoon Nebula M8 in Sagittarius

Protostar Hot, contracting cloud of dust and gases

When the temp. reaches 10,000,000 °C, a star is born

Star forming region in NCG 2366

Star forming region of NCG604

Medium-sized Stars Most common star type Our sun

Red Giant Most of the hydrogen is used up Outer shell begins to expand

As it expands, it cools and becomes red

Core gets hotter – up to 200,000,000 °C – where helium is fused into carbon

Gas drifts off forming a planetary nebula

Eskimo Nebula – NCG2392

MyCn18 – young planetary nebula 8000 light years away

Stingray Nebula – youngest nebula known

Ring Nebula – planetary nebula around a white dwarf

White Dwarf Extremely dense White hot

M4 – comparison of ground based observation to HST

Massive Stars Start like medium-sized stars Become supergiants after red giant stage

Temp can reach 600,000,000 °C Carbon atoms fuse and eventually form iron

Betelgeuse – red supergiant

Supernova Tremendous explosion Heat can reach 1,000,000,000 °C

Iron atoms fuse to form heavier elements Can light up our sky

Southern Crab Nebula

Supernova remnant – Veil Nebula – NGC6992

Neutron Stars Often less than 16 km in diameter Spin very rapidly

Energy is given off in narrow beams Pulsars – appear to give off pulses of energy

2 X-ray pulsars, Geminga and Crab Pulsar

Neutron star

Black Holes Incredibly massive stars Gravity becomes so strong that even light cannot escape

Artist concept of a black hole

Black hole candidate in M87

Black hole in NGC4261