Stellar Evolution

Nuclear fission. It realeases nuclear energy by spitting big atomic nuclei, usually those of uranium. Neutrons are fired at the nuclei. As the neutrons smash into the nuclei they split off more neutrons, which bombard other nuclei, setting of a chain reaction, which makes energy.

The apparent visual magnitude of Beta Herculis is 2.81. It has been known since 1899 that it is in fact a binary star, and modern measurements (including satellite telescope) have resolved the motions and apparent sizes of the two bodies.

Massive stars cannot generate energy from iron fusion because iron fusion does not release energy, rather it absorbs energy. Iron is the most stable element, and fusion of iron requires more energy than it produces, making it an unfavorable process for generating energy in stars. This leads to the collapse of the star's core and triggers a supernova explosion.

If a gamma ray burst hit Earth, it could potentially strip away the ozone layer, leading to an increase in harmful ultraviolet radiation from the sun. This could have catastrophic effects on the environment and life on Earth. However, the likelihood of a gamma ray burst hitting Earth directly is very low.

The remnant core of a star that becomes a supernova will normally be a neutron star, or possibly a pulsar (a rapidly spinning neutron star). The largest of stars would theoretically create a black hole, a singularity containing all of the core's mass at a single point and preventing even light from escaping its massive gravity.

The rapid collapse of the star compresses atoms together and may cause nuclear fusion and make heavier elements.

Thermonuclear fusion is still going on in the core of a red giant, but it is a different type of thermonuclear fusion. The center of the core has reached high enough temperature and pressure that it can now burn helium, producing carbon.

3 4He --> 12C

The large amount of energy released by this type of fusion pushes the outer layers away, making a giant star. The expansion of volume of the surface layer causes it to cool, appearing red. Thus a red giant.

they study the stars the same reason we study most things, to understand.

relly? they studly them because space may hold the awnser to our meaning, how we were created, and how we will end.

The corona is hotter than the photosphere because the sun's magnetic field carries energy upward from the surface and into the chromosphere and corona. The opposite effect is observed when the magnetic fields cause sunspots to form resulting in cooler surfaces.

Our Sun is currently on the Main Sequence stage of it's evolution.

As a G-type star fuses its hydrogen to helium, this helium will gather in the core. As a result, the core will contract under its own weight as hydrogen is being spent. The contraction causes an increased hydrogen fusion rate, increasing the temperature. When insufficient hydrogen remains in the core, the layers above are no longer supported by the outward pressure of radiation, and collapse on top of the core, causing it to contract further, and also initiating hydrogen fusion outside the core. At this point, the star leaves the main sequence, and becomes a red giant. At this stage, the core of the giant may reach critical density for helium fusion to initiate. Since the core is composed of mostly degenerate matter at this stage, there is no regulation of the fusion rate. Also, degenerate matter is less opaque to the energies produced than non-degenerate matter, so conducts them better.

Ehr, to summarize: the helium flash occurs during the red giant stage of G-type stars.

Stars form when enough hydrogen accumulates to cause enough internal pressure and heat to make the ball of hydrogen glow from the fusion of hydrogen to form helium. Depending on the size and temperature of the new star, it will fall along the HR Diagram as a class O,B,A,F,G,K or M star. Class O stars are very big and very hot, giving off blue/white light. Class M stars are small, cool red dwarf stars. Our sun is a class G star, a small star which burns moderately and is yellow.

Depending on the mass of the star, it will burn at different rates. Class O and B stars, although large, burn very fast because they are so hot. Class M stars, being small and cool, can burn for many millions of years longer.

Eventually, all stars run out of fuel and begin to collapse on themselves. What happens next depends on the type of star.

Large, hot stars will explode in a supernova, ejecting their entire blanket of gases into space and leaving behind a small core which will be a pulsar (neutron star), or even a black hole.

Medium stars like our sun will swell their outer layers to become Red Giants (such as Betelguese in Orion). This phase will last for a few million years until the core finally cannot support the outer layers any longer. To give you an idea of size, our sun will eventually send it's outer layers as far out as to engulf Mars.

Once these moderate Red Giants run out of fuel, they collapse and form a white dwarf star, which will be the end result of our sun. After billions of years, they will cease to glow and become black dwarfs. (Do not confuse this with black holes..completely different).

Small red dwarf stars will puff out outer layers in a planetary nebula, but will not have enough energy to explode. They will eventually become small black dwarf stars as they lose their energy and can no longer burn.

This is very brief because this is a very complex process, but I hope this helped.

White dwarf stage. Note that not all stars reach this stage. Some stars experience runaway criticality and go supernova. Also, white dwarf stars in binary systems can still go nova if they are acquiring hydrogen from their partner.

Supernovae are caused by the gravitational collapse of massive stars. When the material in the core of the star reaches the density of an atomic nucleus, nuclear forces (actually "neutron degeneracy pressure," but that's a whole new topic) balance gravity and the collapse is suddenly halted. This creates a shock front between the material that has stopped and the material that is still falling inward. The shock front moves moves outwards (only direction it can go, think about it) through the star and explodes as a supernova.

So, to answer your actual question, that small dense remnant is called a neutron star. If the neutron star can steal some material from somewhere (either another star or perhaps the remains of its parent star), it might become so big that gravity becomes dominant again, and will collapse, this time into a black hole.

Stars have a typical path of development. The details of this path depend on their mass. Smaller stars, like our sun, will gradually grow hotter, until they become a red giant. Ultimately they will shed their outer layers, and a white dwarf remains. Much more massive stars might go nova in stead.

Star clusters are ideal for figuring out certain things of stellar evolution because every star in a cluster is made of basically the same material and therefore has the same composition, they are basically at the same distance from the earth, and they all basically move the same way.

This is ideal because it can be tough to determine whether some stars are closer or farther away (brightness would make you think that a brighter star is closer but this is not always the case) but looking at 2 stars in the same cluster, if one looks brighter, it actually is!

These clusters make it easy for astronomers to see how stars grow up!

Although at the end of a stars life - another "type" of star is born, they are different to the "normal" type of star and are "star" in name only. Most "remnants" of stars should be classed as degenerate stars.

Our Sun (a star) will first turn into a red giant star [See related question] and then a white dwarf star [See related question]

G-type stars, like the sun, will generally go through their main sequence, growing brighter all the time, until they expand to red giants, followed by a helium flash (or possibly several flashes), followed by the shedding of the outer layers of the star, at which time a slowly cooling white dwarf remains, which should, given enough time, cool enough to become a black dwarf.

Stellar evolution states that stars are powered by a hydrogen fusion reaction. When a star has burned up its hydrogen, this reaction runs out, and its core will contract and heat up causing the hydrogen shell to ignite. This causes the star to expand into a giant star. Depending on the solar mass of the star, it will evolve into different objects. If its mass is in the 0.3 to 3 range, its core, now fusing helium will degenerate before the helium has a chance to ignite, and the explosion that results will be absorbed into the star itself. A star with a mass less than 0.4 will evolve into a white dwarf. If its mass is between 0.4 and 0.3, it will become a red giant and then burn out into a white dwarf. Stars that are more massive will collapse explosively as a super nova, and if it is larger than 25 stellar masses, it will be a neutron star.

The collapse of a star is based on its age. When it runs out of "Fuel" its inside contracts as the outside expands. it can then super nova or collapse into a tiny star.

white dwarf. unless you count black dwarf of which none have been observed, only theorized.