Exam 3 Flashcards
(71 cards)
Is there a minimum mass to a planet? A maximum mass?
Both
What provides pressure support for the Sun?
Nuclear fusion
Patterns in the stars tell us their
life stage
The mass of a star controls its rate of
core nuclear fusion
High-mass stars
live fast and die young
What do the bright blue stars in the Pleides tell us about their age?
They are high mass and young
Supernova
Stars born with >10x the Sun’s mass end their lives explosively
What mass of host star would be most likely to have a
planet with life?
0.3 Msun
“Planetary Nebula”
Eventually, stars shed their outer envelopes and only core remains
In a few billion years, the radius of the Sun will
increase
hydrostatic equilibrium
outward pressure must balance inward pull of gravity
Pressure in Sun comes from
H [hydrogen] to He [helium] fusion
4 H atoms
have a little less mass than 1 He atom, and that mass difference was converted directly into energy from fusion
Patterns in temperature vs. luminosity (intrinsic brightness) reveal
the life cycles of stars, where mass is the factor controls how fast star ages
When low-mass stars like the Sun run out of fuel for fusion its radius eventually expands into
red giant
When it is a giant, The Sun will have a radius extending to
Earth’s orbit
Earth is likely to be engulfed by the Sun then, in about
5-6 billion years
Eventually only the core (60% of Sun’s mass) will be left:
white dwarf
White dwarf
has about 60% the Sun’s mass packed into a volume the size of the Earth (1 teaspoon of white dwarf weighs more than a car)
All stars less than 8x the Sun’s mass
first become red giants than end their lives as white dwarfs when they run out of core H & He
In a few billion years, the surface temperature of Earth will
increase
What is the remnant white dwarf mostly composed of?
Carbon/Oxygen
Massive stars have
massive core temperatures
Heavier element fusion requires
hotter core temperatures
