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? 1 millionth the mass of the Sun? 1 thousandth the mass of the Sun? Our Sun is an average star.
What Makes a Star a Star? Fusion More Likely • A body that satisfies two conditions: • It is bound by self-gravity • It radiates energy supplied by and internal source An introduction to the theory of stellar structure and evolution by Dina Prialnik HotterCore Central Pressure Gravity After detailed calculations, 0.08 Solar Mass is the smallest mass to start core fusion of Hydrogen. Mass
Could a Star Have a Maximum Mass? Compared to our Sun, how much mass could a star possibly have? Maximum mass of a star is an estimated 150 Solar Masses Our Sun is an average star. Radiation Pressure Winds - Mass loss!
Brighter Mass = Destiny These stars pop off in an astronomical blink of the eye These stars, once made, will basically last forever Dimmer Hotter Cooler
150 Msun 120 Msun 100 Msun Hotter Cooler Wolf-Rayet Brighter Luminous Blue Variable Supernova? Blue Super Giant Fusing core He, then core C, Fusing H (CNO) All that takes around 3-4 million years Dimmer
Carinae What do we know? Brightened 10 fold in 5 years (1840’s) Most luminous known star in our galaxy What have we inferred? Distance is ~ 7500 light years Lost 5 solar masses in 1840’s event Puts out as much energy in 6 seconds that our Sun does in 1 year Mass ~100-150 Msun 30-60 Msun star orbiting every 5.5 years Stellar winds ~100 billion times the Sun’s
Carinae “We really don’t understand the behavior and evolution of 100 Msun stars” Nathan Smith (University of Colorado)
Further Reading Thanks! Ask me questions! 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
How heavy is a Star Compared to our Sun, how much mass could a star possibly have? Betelgeuse is ~14 times the Mass of the Sun Size of Betelgeuse Size of Earth’s Orbit Size of Jupiter’s Orbit