Astronomy Today: Stars and Galaxies: Chapter 20
Cooler
Compared to other stars on the HR diagram, red giant stars are so named because they are
White dwarf
A high mass star will evolve off the main sequence to become a
triple-alpha process
3 He -> C + energy
contact binary
A binary star system in which both members fill their Roche lobes. The binary system now consists of two nuclear burning stellar car surrounded by a continuous common envelope.
white dwarf
A set of the dwarf star with a surface temperature that is hot, so that the object glows white. White dwarfs are typically about the size of the earth with a mass comparable to the sun.
After the helium flash
A star is located on the asymptotic giant branch of the H-R diagram when
white dwarf
A star like the sun will end up as a
Most of the hydrogen in its core
A star will evolve off the main sequence when it uses up
Useful is studying he evolution of stars, a table of numerical values, useful in studying the interiors of stars
A stellar model is
Protons
A white work and supported by the pressure of tape packed
Hotter
After the core of the sun like star starts to fuse helium on the horizontal branch, the core becomes
helium flash
And explosive event in the post-main-sequence evolution of a low-mass star. When helium fusion begins in a dense stellar core, the burning is explosive in nature. He continues until the energy released is enough to expand the car, at which point the star achieve stable equilibrium again.
Cooler and brighter
As a star exhaust the hydrogen in its core and the core contracts, the star becomes
Begins to fade and drop down to become a white dwarf
As the fusion process dies out, the star begins to do what on the H - R diagram?
When the central temperature reaches the nearly 100,000,000 K necessary.
At what temperature does a helium flash occur?
CNO cycle
Chain of reaction is that converts hydrogen into helium using carbon, nitrogen, and oxygen as catalysts.
Denser
Compared to the sun, stars planted near the bottom left of the H - R diagram are much
hydrostatic equilibrium
Condition in a star or other fluid body in which gravity is in word Paul is exactly balance by internal forces due to pressure
No the universe is not yet old enough to form black dwarfs
Do mini black dwarfs if exist in our galaxy?
CNO cycle
For more massive stars with higher central temperatures what is the dominant process is?
hydrogen shell burning
Fusion of hydrogen in a shell that is driven by contraction and heating of the helium core. Once hydrogen is depleted in the core of a star, hydrogen burning stops and the core contracts due to gravity, causing the temperature to rise, heating the surrounding layers of hydrogen in the star, and increasing the burning right there.
Helium burning shell
Shell of burning heilium gas surrounding a nonburning stellar core of carbon ash.
Very slow
Since a white dwarf star is very dense the continued calling is
By determining which of the stars have already left the main sequence
How can astronomers Measure the age of a star cluster?
For a few hours
How long can a star like the sun keep burning hydrogen in its core?
Two
How many reactions are there and the proton - proton cycle?
Greater than
In the hydrogen fusion process what occurs in normal stars, the total mass of the material that goes into the reaction is____the mass of what comes out
False
Main sequence stars like the sun swell into giant stars when the rate of hydrogen fusion increases dramatically in their cores
More rapidly than the sun
On the main sequence, massive stars burn their hydrogen fuel
Increases
Over the stars life span as a main sequence star the luminosity of the star slowly
asymptotic giant branch
Path on the H-R diagram corresponding to the changes that a star undergoes after helium burning ceases in the core. At this stage, the carbon core shrinks and drives the expansion of the envelope, and the star becomes a swollen red giant for a second time.
About 100 times its current size. This is the equivalent to about 70,000,000 km or almost half an AU
Roughly how big will the Sunday come when it enters the red giant phase?
blue straggler
Star found on the main sequence of the H - R diagram, but which should already have evolved off the main sequence, given its location on the diagram; thought to have form from mergers of lower mass stars.
red-giant branch
That section of the evolutionary track of a star that corresponds to continued healing from rapid hydrogen shell burning, which drives a steady expansion and calling of the outer envelope of the star. As the star gets larger in radius and its surface temperature cools, it becomes a red giant.
White Dwarf Region
The bottom left-hand corner of the H - R diagram, where the white dwarf stars are plotted
False
The central star of the planetary nebula is a white dwarf
planetary nebula
The ejected envelope of a giant red star, spread over a volume roughly the size of our solar system.
Black Dwarf
The end-point of the evolution of an isolated, low-mass star. After the white dwarf stage, the star cools to the point where it is a dark "clinker" in interstellar space.
core hydrogen burning
The energy burning stage for main sequence stars, in which they helium is produced by hydrogen fusion in the central region of the star. A typical star spends up to 90% of its lifetime in Hydrostatic equilibrium brought about by the balance between gravity and the energy generated by core hydrogen burning.
Proton-proton cycle
The energy for the thermal pressure in a star like the sun, that counteract the forces of gravity, is supplied by a hydrogen fusion reaction called the
Up and to the left
The evolutionary track of a massive star's starting point (stage seven) would be
mass transfer
The flow of gases from one star in a binary system to the other.
zero age main sequence (ZAMS)
The location of a star on the main sequence when it first becomes stable
electron degeneracy pressure
The pressure produced by the resistance of electrons to compression once they are squeeze to the point of contact.
Hydrogen
The primary constitute of most stars is
Neutrinos
The products of nuclear fusion reactions that most easily escape the interior of a star are
Subgiant branch
The section of the evolutionary track of a star that corresponds to changes that occur just after hydrogen is depleted in the core, and the core hydrogen burning Caesars. Shell hydrogen burning weeds the outer layers of the star, which causes a general expansion of the stellar and below.
Proton-proton cycle and CNO cycle
The two primary processes that provider energy for main sequence stars are?
Red Giant Region
The upper right-hand corner of the H - R diagram, we are red giant stars are plotted
Roche Lobe
The volume of space a star controls gravitationally within a binary system.
Supergiant
What is the lowest density star
Proton-proton cycle
What process is where one hydrogen nucleus fuses with another hydrogen nucleus?
Proton-proton cycle
When does central temperature of a main sequence star is less than 16,000,000 K the dominant process is?
CNO cycle
When protons collide with too much energy to permit fusion causing other atoms to serve a catalytic roll to permit what process?
Triple-alpha process
When temperatures in the helium which core of a star exceeded 100 million Kay, the healing begins to fuse in what process?
90% hydrogen and 10% helium
When the star first become stable, the core of the story is about
Mercury
When the sun becomes a red giant, it's photosphere may reach the orbit of
The upper right of the HR diagram
When the sun is on the red giant branch, it will be found at
Red giant
When the sun leaves the main sequence it's next stage in evolution is to become a
Brighter
When the sun leaves the main sequence, it will become
To the extreme left as a bright O star
Where does the central star of the planetary nebula plot on the H - R diagram?
Lower edge of the main sequence
Where is the zero age main sequence on the H-R diagram?
True
Whitehorse do not produce new energy they just radiate away excess energy as they cool
They are very small and therefore faint and hard to observe
Why are white dwarfs hard to observe?
It signifies the star jumping from stage 9 to stage 10
Why is the depletion of hydrogen in the core of a star such an important event?
red giant
a large, reddish star late in its life cycle that fuses helium into carbon or oxygen
horizontal branch
a region on the H-R diagram defined by stars burning helium to carbon in a stable core
Subgiant
helium core but no fusion occurring, grows in size. Star on the sub giant branch of the H - R diagram.
main-sequence turnoff
location in the H-R diagram where stars begin to leave the main sequence