Download Stages of stars - University of Dayton

Megan Garmes
Betsy Nichols
Stars are hot bodies of glowing gas that start their life in
Nebulae.
Career of a star depends mostly on its mass.
The more massive the star, the more pressure is built
up inside.
Stars radiate energy in all directions into space, allowing
us to unravel the secrets of our universe.
Different Types of Stars
A. Giants
D. Supergiants
B. White Dwarfs
E. Sun
C. Main Sequence
It shows that the temperature coincides with the luminosity, the hotter the star the higher
the luminosity the star has. You can also tell the size of each star from the graph as
the higher the radius the higher the temperature and luminosity.
Vary in size, mass, and temperature
The color of a star is determined by its temperature
Hottest stars are blue and the coolest are red
Nuclear fusion in the stars core produces the star’s energy
Brightness is measured in magnitude (the brighter the star, the lower
the magnitude)
There are two types of magnitude:
Apparent magnitude-brightness seen from Earth
Absolute magnitude-brightness seen from a standard distance of
36.2 light years
Life of a small star
Stage 1:
Stars are born in a region of high density Nebula, and condenses into a huge
globule of gas and dust and contracts under its own gravity.
Stage 2:
A region of condensing matter will begin to heat up and start to glow forming
Protostars. If a protostar contains enough matter the central temperature reaches
15 million degrees centigrade.
Stage 3:
At this temperature, nuclear reactions in which hydrogen fuses to form helium can
start.
Outflow=red
Protstar=green
Stage 4:
The star begins to release energy, stopping it from contracting even more and
causes it to shine. It is now a Main Sequence Star.
Stage 5:
A star of one solar mass remains in main sequence for about 10 billion years, until
all of the hydrogen has fused to form helium.
Stage 6:
The helium core now starts to contract further and reactions begin to occur in a
shell around the core.
Stage 7:
The core is hot enough for the helium to fuse to form carbon. The outer layers begin
to expand, cool and shine less brightly. The expanding star is now called a Red Giant.
Stage 8:
The helium core runs out, and the outer layers drift of away from the core as a
gaseous shell, this gas that surrounds the core is called a Planetary Nebula.
Stage 9:
The remaining core ( 80% of the original star) is now in its final stages. The core
becomes a White Dwarf the star eventually cools and dims. When it stops shining, the
now dead star is called a Black Dwarf.
Is an expanded small star, this happens because the helium
is hot enough to convert into carbon, and the outer layers of the core
begin to expand and shine less brightly.
Life of a massive star (10 solar masses)
Stage 1:
Massive stars evolve in a similar way to a small stars until it reaches its main
sequence stage. The stars shine steadily until the hydrogen has fused to form
helium ( it takes billions of years in a small star, but only millions in a massive star).
Stage 2:
 The massive star then becomes a Red Supergiant and starts of with a helium core
surrounded by a shell of cooling, expanding gas.
Just like in the process of a small star, a massive star
expands into a large mass called a red super giant
Stage 3:
In the next million years a series of nuclear reactions occur forming different
elements in shells around the iron core.
Stage 4:
The core collapses in less than a second, causing an explosion called a
Supernova, in which a shock wave blows of the outer layers of the star. (The actual
supernova shines brighter than the entire galaxy for a short time).
The star going into a stage called Supernova and contracting to become a neutron
star
Final Stage
Stage 5:
Sometimes the core survives the explosion. If the surviving core is
between 1.5 - 3 solar masses it contracts to become a a tiny, very dense
Neutron Star. If the core is much greater than 3 solar masses, the core
contracts to become a Black Hole.
Sky above 39°6'6"N 84°30'34"W at Mon 2004 Apr 5 19:37 UTC
Explain symbols in the map.
Burnout and Death of Stars
Death of Low Mass Stars:
>May remain on main sequence for up to 100 billion
years
>Never evolve to become bloated red giants
>Remain as stable main sequence stars until they
consume their hydrogen fuel and collapse into white
dwarfs
Death of Massive Stars:
>Have relatively short life spans
>Terminate in an explosion known as a supernova
>During this event, a star becomes millions of times
brighter when it consumes most of its nuclear fuel
>Predictions say that stars condense into very hot
bodies known as neutron stars
•White Dwarfs
-Extremely small stars with densities greater than any known
terrestrial material
•Neutron Stars
-remnants thought to be of supernova events
•Black Holes
-massive star that has collapsed to such a small
volume that its gravity prevents the escape of all
radiation