Download Chapter 13 Notes – The Deaths of Stars

Chapter 13 Notes – The Deaths of Stars
Astronomy
Name:
Date:
I. The End of a Star’s Life
 When all the __________________ fuel in a star is used up, _______________ will win over
pressure and the star will die
 High-mass stars will die ______________, in a gigantic explosion called a
____________________
 Less massive stars will die in a less dramatic event called a _____________.
II. Red Dwarfs
 Stars with less than __________ solar masses are completely convective.
 Hydrogen and helium remain well _______________ throughout the entire star
 No phase of _____________ burning with expansion to ______________
 Not hot enough to ignite ____________ burning
III. Sunlike stars
 0.4 to _________ solar masses
 develop a ________________ core
 Expansion to red giant during hydrogen burning ____________ phase
 Ignition of ___________ burning in the Helium core
 Formation of a _______________ and oxygen core
IV. Mass Loss from Stars
 Stars like our sun are constantly losing mass in a ______________ wind (solar wind)
 The more massive the star, the _______________ its stellar wind
V. Planetary Nebulae (final breaths of sun-like stars)
 Remnants of stars with 1 to ______________ solar masses
 Radii: _________ to 3 light years
 Expanding at about 10 to ________________
 Less than ____________________ years old
 Have nothing to do with _________________!
 Slow wind from a ____________________ blows away cool, outer layers of the star
 Fast wind from hot, inner layers of the star overtakes the slow wind and __________________
it -> planetary nebula
 Often asymmetric, possibly due to:
o Stellar ________________
o ________________ fields
o _____________ disks around the stars
VI. White Dwarfs (remnants of sun-like stars)
 sunlike stars build up a C, O core, which does not ignite ________________ fusion
 He-burning shell keeps dumping C and O onto the core until it _______________ and the
matter becomes degenerate, forming a White Dwarf
 _______________ stellar remnant (C, O core)
 Extremely dense: 1 ______________ of WD material has a mass of ________ tons!
 Mass = _______________
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Temp = _________________
Luminosity = ________________
White dwarfs are found in the _____________________ corner of the H-R diagram
Eventually, a white dwarf will run out of fuel and form a ____________ dwarf
Nova Explosions:
o ____________________, accreted through the accretion disk (from
__________________ star), accumulates on the surface of the white dwarf
o Very hot, dense layer of non-_____________ hydrogen on the WD surface
o Explosive onset of ___________ fusion
o Nova explosion
VII. The Fate of our Sun and the End of Earth
 Sun will expand to a red giant in ______________ billion years
 Expands to ______________ radius
 Earth will then be ___________________
 Sun MAY form a ________________ nebula (but uncertain)
 Sun’s C, O core will become a ______________ dwarf
VIII. The Deaths of Massive Stars: Supernovae
 Final stages of fusion in high-mass stars ( ___________ solar masses) leading to the formation
of an ___________ core, happen extremely rapidly: _________ burning only lasts for about
_______ day
 Iron core ultimately _________________, triggering an explosion that destroys the star: A
__________________!
 Several hundreds to ________________ of years later, the ejected material from supernovae is
still visible as Supernova _______________.
 The shocks of supernova remnants accelerate _______________ and electrons to extremely
high, relativistic energies and are called _______________ Rays.
 Nearby supernovae (less than __________ light years) could kill many life forms on Earth
through __________________ radiation and high-energy particles.
 At this time, no star capable of producing a supernova is less than 50 ly away.
 Most massive star known (about __________ solar masses) is _________________ light years
from Earth.