What is the net result of the CNO cycle?
Four hydrogen nuclei are transformed into one helium nucleus, two neutrinos, and energy.
What is the net result of the proton proton chain?
The net effect is
to convert hydrogen to helium
, with the energy released going into the particles and gamma-rays produced at each step of the sequence.
When two atomic nuclei come together to form a new species of atom what force must be overcome?
At large distances, two nuclei repel one another because of the repulsive electrostatic force between their positively charged protons. If two nuclei can be brought close enough together, however, the electrostatic repulsion can be overcome by
the attractive nuclear force
, which is stronger at close distances.
What forces are in mechanical balance for a star to be on the main sequence quizlet?
While self-gravity pulls the star inward and tries to make it collapse,
thermal pressure (heat created by fusion) pushes outward
. These two forces cancel each other out in a main sequence star, thus making it stable.
What is the significance of the proton proton cycle and the CNO cycle?
The proton-proton chain and the CNO cycle both convert four hydrogen nuclei into one helium nucleus, releasing energy. The CNO cycle is different from the proton-proton chain because it requires carbon to be present to act as a catalyst.
Which is the final result of the proton-proton chain quizlet?
The proton-proton chain is a set of three reactions that, in the end,
change 4 protons (Hydrogen) into 1 Helium
. There are also two neutrinos created during the formation of Helium.
Where does the CNO cycle occur?
It also occurs at temperatures of 4*10^6 Kelvin (4 million). The Carbon-Nitrogen-Oxygen cycle (or CNO cycle) occurs in
stars that are approximately 1.3 times the mass of the sun
.
What results from the fusion of nuclei and nucleus B?
Nuclear fusion is a reaction in which two nuclei are combined to form a larger nucleus. It
releases energy when light nuclei are fused to form medium-mass nuclei
. being the principal sequence of energy-producing reactions in our Sun.
Is cold fusion possible?
Cold fusion is a hypothesized type of nuclear reaction that would occur at, or near, room temperature. …
There is currently no accepted theoretical model that would allow cold fusion to occur
.
What is the net fusion reaction that produces energy in the core of the sun?
In the core of the Sun hydrogen is being converted into helium. This is called
nuclear fusion
. It takes four hydrogen atoms to fuse into each helium atom. During the process some of the mass is converted into energy.
What happens in the carbon nitrogen oxygen CNO cycle quizlet?
A chain of nuclear reactions, involving carbon as a catalyst and including nitrogen and oxygen as intermediaries, that transforms
four hydrogen nuclei into one helium nucleus with a resulting release in energy
. The CNO cycle is important only in stars hotter than the Sun.
What are the outward forces that act on a star What are the inward forces How do these compare?
the outward force that acts on a star is thermal pressure. the inward force that acts on a star is
gravity
.
What two forces must be in balance for a star to be stable?
Stars live out their lives in an exquisitely detailed equilibrium, or balance, between two powerful forces
— outward pressure and the inward pull of gravity
. The gravity force is a property of the mass of the star, and in order to support itself against gravity the star generates energy in its core.
What is the net result of the CNO cycle?
CNO Cycle:
The result is a
net conversion of 4 protons into 1 Helium nucleus
, with a release of energy in the form of gamma-ray photons, neutrinos, and positrons.
What is the CNO cycle astronomy quizlet?
The CNO cycle is
a nuclear fusion cycle involving carbon, nitrogen, and oxygen
. It is a more ecient way of fusing hydrogen into helium and is used by stars more massive than our Sun.
What does the CNO cycle produce?
The ‘CNO cycle’ refers to the Carbon-Nitrogen-Oxygen cycle, a process of stellar nucleosynthesis in which stars on the Main Sequence fuse hydrogen into helium via a six-stage sequence of reactions. This sequence proceeds as follows: A carbon-12 nucleus captures a proton and emits a gamma ray, producing
nitrogen-13
.
What happens to the lost mass in the proton proton cycle?
In the proton-proton cycle, the helium atom and neutrino have less mass than the original hydrogen. What happens to the “lost” mass?
It is recycled back into hydrogen. It is ejected into space.
Why is it called the CNO cycle?
For more massive stars the PP chain can still occur, but
there is another sequence of reactions that becomes more favorable for converting hydrogen to helium
. It is called the CNO cycle, which stands for the carbon-nitrogen-oxygen cycle.
What is it about the Sun’s corona that astronomers don’t understand quizlet?
What is it about the Sun’s corona that astronomers don’t understand?
The corona is much hotter than layers of the Sun that are closer to the solar interior
. … They are extremely hot, but cooler than the surrounding areas of the Sun.
What are the three final options for a star when it dies?
When the helium fuel runs out, the core will expand and cool. The upper layers will expand and eject material that will collect around the dying star to form a planetary nebula. Finally,
the core will cool into a white dwarf and then eventually into a black dwarf
. This entire process will take a few billion years.
Which reactions or decays take place in the hot CNO cycle?
Energy production and nucleosynthesis in the cold CNO cycles depend critically on the reaction rates of the various proton capture processes, but in the hot CNO cycles, they are characterized by the
β-decay rates of 14O, 15O, and 18Ne (12)
.
Why does not CNO cycle occur in stars like our Sun?
The proton-proton chain reaction is dominant in our Sun and stars smaller than about 1.3 solar masses. This reaction is Hydrogen → Deuterium → Helium-3 → Helium-4. The CNO cycle uses Carbon as a catalyst.
The Sun isn’t hot enough to make this efficient
so it only generates about 10% of its output from CNO.
Which of the following is the main result of nuclear fission?
Nuclear fission is a reaction in which the nucleus of an atom splits into two or more smaller nuclei. The fission process often produces
gamma photons
, and releases a very large amount of energy even by the energetic standards of radioactive decay.
What is the fusion equation?
An important fusion reaction for practical energy generation is that between deuterium and tritium (the D-T fusion reaction). It produces helium (He) and a neutron (n) and is written
D + T → He + n
. To the left of the arrow (before the reaction) there are two protons and three neutrons. The same is true on the right.
How does nuclear fusion result in a release of energy?
In a fusion reaction,
two light nuclei merge to form a single heavier nucleus
. The process releases energy because the total mass of the resulting single nucleus is less than the mass of the two original nuclei. The leftover mass becomes energy. … Fusion can involve many different elements in the periodic table.
Why fusion is impossible on Earth?
Normally, fusion is not possible because
the strongly repulsive electrostatic forces between the positively charged nuclei prevent
them from getting close enough together to collide and for fusion to occur.
How is energy produced in the sun’s core quizlet?
Energy is made
through the process of nuclear fusion
. This is when two hydrogen nuclei join to make helium. This occurs in the sun’s core where there is very high pressure and temperature.
Which best describes a chain reaction associated with a nuclear reaction quizlet?
Which best describes a chain reaction associated with a nuclear reaction?
Neutrons released during a fission reaction cause other nuclei to split
. … Disposal of radioactive waste is a major concern in nuclear power production.
Why don t stars collapse under their own gravity?
Stars don’t collapse under their own weight because
the inward force of gravity balances the equal and opposite outward force of nuclear fusion
.
What is hot fusion?
Nuclear fusion occurring at
very high temperatures
, especially as a controlled process viewed as a potential source of energy.
Who discovered cold?
Martin Fleischmann
, who in 1989 claimed to have discovered cold fusion, died in his home in England on Friday, August 3rd, following a long battle with Parkinson’s disease.
Why does a star become a red giant?
Stars spend most of their lives fusing hydrogen nuclei in their core to create helium. When the hydrogen in the centre of a star runs out, the star begins to use hydrogen further out from its core. This causes the
outer layers of the star to expand and cool
. … The star is now a red giant.
Why do stars shine?
Stars shine because
they are extremely hot
(which is why fire gives off light — because it is hot). The source of their energy is nuclear reactions going on deep inside the stars. In most stars, like our sun, hydrogen is being converted into helium, a process which gives off energy that heats the star.
What will the sun’s approximate luminosity be during the Subgiant stage?
Hence, approximate luminosity corresponding to subgiant stage is
10 solar unit
.
What types of stars end their lives with supernovae quizlet?
ANSWER:
Both low- and high-mass stars
end their lives in supernovas and leave behind neutron stars or black holes.
What happens to a high mass star when core helium fusion ceases quizlet?
It is only a matter of time until a helium core-fusion star converts al its core helium into carbon. When the core helium is exhausted,
fusion will again cease
, and the star will once again go out of energy balance.
What is the outward force in a main sequence star?
The simple model of any main sequence star is of a dense gas/fluid in a state of hydrostatic equilibrium. The inward acting force, gravity, is balanced by outward acting forces of
gas pressure and the radiation pressure
.
What are the inward and outward forces on a stable star in the main sequence?
A star on the main sequence is stable because it is steadily fusing hydrogen into helium in the core. … While self-gravity pulls the star inward and tries to make it collapse,
thermal pressure (heat created by fusion) pushes outward
. These two forces cancel each other out in a main sequence star, thus making it stable.
Why do stars leave the main sequence?
Eventually,
a main sequence star burns through the hydrogen in its core
, reaching the end of its life cycle. At this point, it leaves the main sequence. … Then the pressure of fusion provides an outward thrust that expands the star several times larger than its original size, forming a red giant.
Where does the CNO cycle occur?
It also occurs at temperatures of 4*10^6 Kelvin (4 million). The Carbon-Nitrogen-Oxygen cycle (or CNO cycle) occurs in
stars that are approximately 1.3 times the mass of the sun
.
How does stellar nucleosynthesis occur?
Stellar nucleosynthesis is the process by
which elements are created within stars by combining the protons and neutrons together from the nuclei of lighter elements
. … Fusion inside stars transforms hydrogen into helium, heat, and radiation. Heavier elements are created in different types of stars as they die or explode.
What is stellar nucleus?
Definition. Stellar nucleosynthesis is
the process involving nuclear reactions through which fresh atomic nuclei are synthesized from pre-existing nuclei or
nucleons. The first stage of nucleosynthesis occurred in the hot, early Universe, with the production of H, He, and traces of Li-7 (primordial nucleosynthesis).
