Massive Stars:
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Massive Stars:Party Hard, Live Fast, Die Explosively
Phil Rosenfield
How did they come up with this?
Death Star Explosion
Goals of this talk
Understand how mass determines a star’s path to ultimate demise
Appreciate the craziness of very massive stars
Be able to talk about our current understanding of Carinae
How Massive are Stars?
Compared to our Sun, how little mass could a star possibly have to still be considered a star?
Our Sun is an average star.
1 millionth the mass of the Sun?1 thousandth the mass of the Sun?
What Makes a Star a Star?
A body that satisfies two conditions: (a) It is bound by self-gravity(b) It radiates energy supplied by and internal source
An introduction to the theory of stellar structure and evolution
by Dina Prialnik
After detailed calculations, 0.08 Solar Mass is the smallest mass to start core fusion of Hydrogen.
Mass
Gravity
Central Pressure
Hotter Core
Fusion More Likely
Could a Star Have a Maximum Mass?
Compared to our Sun, how much mass could a star possibly have?
Our Sun is an average star.
Maximum mass of a star is an estimated
150 Solar Masses
Radiation PressureWinds - Mass loss!
Mass = Destiny
Hotter Cooler
Dimmer
Brighter
These stars, once made, will basically last forever
These stars pop off in an astronomical blink of the eye
Dimmer
Brighter
Hotter Cooler
100 Msun
120 Msun
150 Msun
Fusing H(CNO)
Blue Super Giant
Luminous Blue VariableWolf-Rayet
Supe
rnov
a?
Fusing core He, then core C,
All that takes around 3-4 million years
CarinaeWhat do we know?
Most luminous known star in our galaxy
Puts out as much energy in 6 seconds that our Sun does in 1 yearStellar winds ~100 billion times the Sun’s
Distance is ~ 7500 light years
Brightened 10 fold in 5 years (1840’s)
What have we inferred?
Lost 5 solar masses in 1840’s event
Mass ~100-150 Msun
30-60 Msun star orbiting every 5.5 years
Carinae
“We really don’t understand the behavior and evolution of 100 Msun stars” Nathan Smith (University of
Colorado)
Further Reading
Naeye, Robert. “Eta Carinae” Sky and Telescope. Oct 2004, p43
Liu, Charles. “Shadowy partner: astronomers may have detected what lurks in the shadow of the giant star Eta Carinae.” Natural History, Oct 2004, p72
Thanks! Ask me questions!
How heavy is a Star
Compared to our Sun, how much mass could a star possibly have?
Size of Betelgeuse
Size of Earth’s Orbit
Size of Jupiter’s Orbit
Betelgeuse is ~14 times the Mass of the Sun
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