The Life Of A Star

The Life of Star

Space may seem empty, but actually it is filled with thinly spread gas and dust. This gas and dust is called interstellar medium. The atoms of gas are mostly hydrogen which is H2, and the gas atoms are typically about a centimeter apart. The dust is mostly microscopic grains and combines only a few percent of the matter between stars. The dust is mostly carbon and silicon. In some places, this interstellar medium is collected into a big cloud of dust and gas known as a nebula. This is the birthplace of stars because the gas and dust is what makes up a star.

Small Stars:

Stage 1- Stars are born in a region of high density which is located within the Nebula, and condenses into a huge sphere-like shape of gas and dust and contracts under its own gravity within a central pull.

Stage 2 - A region of condensing matter will begin to heat up and start to glow forming a Protostar. If a protostar contains enough matter of hydrogen the central temperature reaches 15 million degrees centigrade.

Stage 3 - At this temperature, nuclear reactions in which hydrogen fuses to form helium will start.

Stage 4 - The star begins to ...

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Small Stars:

Stage 3 - At this temperature, nuclear reactions in which hydrogen fuses to form helium will start.

Stage 4 - The star begins to release energy, stopping it from contracting even more and causes it to shine. This means that it is in its main sequence in its life as a star.

Stage 5 - A small star will be remaining in its main sequence for about 10 billion years, until all of the hydrogen has fused to form helium.

Stage 6 - The helium core now starts to contract further and reactions begin to occur in a shell around the core.

Stage 7 - The core is hot enough for the helium to fuse to form carbon. The outer layer and then begins to expand, cool and shines less brightly. The expanding star is now called a Red Giant.

Stage 8 - The helium core runs out, and the outer layers drift and go far from the core as a gaseous shell, this gas that surrounds the core is called a Planetary Nebula.

Stage 9 - The remaining core is now in its final stages. The core becomes a White Dwarf the star eventually cools and dims. When it stops shining, the now dead star is called a Black Dwarf.

Massive Stars:

Stage 1 - Massive stars evolve in a similar way to a small star until it reaches its main sequence stage. The stars shine steadily until the hydrogen has fused to form helium, it takes billions of years in a small star, but only millions in a massive star.

Stage 2 - The massive star then becomes a Red Supergiant and starts off with a helium core surrounded by a shell of cooling, expanding gas.

The massive star is much bigger in its expanding stage.

Stage 3 - In the next million years a series of nuclear reactions occur forming different elements in shells around the iron core.

Stage 4 - The core collapses in less than a second, causing an explosion called a Supernova, in which a shock wave blows off the outer layers of the star. The actual supernova shines brighter than the entire galaxy for a short period time!

Stage 5 - Sometimes the core survives the explosion. The surviving core is small contracts to become a tiny, very dense Neutron Star. If the core has a much greater mass, the core contracts to become a Black Hole.

Peer Reviews

Here's what a star student thought of this essay

pictureperfect

28th of Jul 2012

Quality of writing

The layout of this piece of work makes it difficult to follow at times, firstly, the writing is in a bullet point format, which is not something I would recommend as it can make an essay feel jumpy and at this level of qualification you should be able to write scientific information in continual prose, you should at least attempt to do so as this is the accepted way to write a scientific essay. Secondly, the way in which the candidate has placed images throughout their work means that the information is constantly jumping form side to side and this again makes the essay very difficult to follow. If you plan to include images, then you should make sure you do so in a way that is not intrusive to the essay. That said, the candidate does use appropriate scientific terms throughout their work and with the exception of the essay title, which should be ‘The life of a star’ there are no issues with spelling or grammar.

Level of analysis

Though the information the candidate has given is accurate, which demonstrates a good understanding of this topic, they have given a fairly brief description of each of the stages of the life cycle of a star. Had they taken the time to throughly research this topic, they could have provide more detail, this would make the essay more enjoyable to read and it would have given the candidate the opportunity to expand their knowledge, which shows enthusiasm and dedication to your subject. However, if you do take the time to undergo some research, you must include a bibliography stating the resources you have used, so that you can avoid accusations of plagiarism. On another note, this piece of work comes to an abrupt end as the candidate has not concluded their work, a conclusion is vital for any type of essay, as this allows you draw your essay to a close and it gives you a chance to leave the reader with a good impression of your work. When writing your conclusion, you should give a summary of the most important points you have mentioned in your essay and you should state why these are important, as this allows you to tie together any lose ends. You also need to give a personal response to your topic, this could be what you learnt from writing your essay, this is important, as your teacher/examiner is interested in what you have to say.

Response to question

The candidates response is fairly straightforward, they haven’t provided a great deal of detail and their are several areas for improvement. One of which is the lack of a clear introduction, you should always write an introductory paragraph for this type of work. It is important that your introduction states exactly what you plan to discuss within your essay so that the premise of your work is clear. You also need to briefly introduce your topic, in this case you should state what a star is and perhaps state something along the lines of ‘All stars are formed in space’ and ‘The formation for a star takes place in nebulae.’ You can then use your first paragraph to go into more detail.

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