The Life of a Star
- Date: 2007-08-28 - Word Count: 945
Share This!
Stars are familiar objects. We see them every day and every night. A single star, our Sun, makes it possible for life on earth to thrive. Stars live so long that they seem eternal to us. But they all had a beginning, and they'll all have an end, too.
Stars begin their lives in immense clouds of gas and dust called nebulae. Nebulae contain mostly hydrogen gas, with a little helium. In most places, a nebula is often so gossamer-thin that if you walked through one, you'd never notice. However, there are some areas in a nebula where gravity causes the gas and dust to coalesce, getting more and more dense and hot.
As more and more material clumps together in these areas, the temperature inside can get extremely hot-around fifteen million degrees. The gravitational pressure is also so immense that the electrons within the atoms of hydrogen and helium are stripped, leaving only the nuclei. As the gravitational force increases, the atomic nuclei fuse. This event is called nuclear fusion. It creates an enormous outpouring of energy strong enough to counteract the crushing gravitational force. The energy pours out into space as light, heat, and electromagnetic radiation. A new star is born, and it begins to shine.
Throughout its life, a star is caught in a balancing act between the crushing forces of gravity and the explosive forces of nuclear fusion within its core. As long as there is material within the star's core that can undergo the process of nuclear fusion, the star will fight gravity and continue to shine. But when the star runs out of fuel, it dies.
Most stars are the size of our sun or smaller. Our sun is a yellow dwarf star, and it's fairly average within the universe. Stars the size of our sun usually emit light in the yellow or orange spectrum, and they live for about ten billion years.
The process of nuclear fusion converts hydrogen into helium. A star the size of our sun turns all its hydrogen into helium, and then starts converting helium into oxygen and carbon as it ages. The oxygen we breathe, and the carbon that provides the most crucial material for life on earth, was created inside a star like our sun.
As a medium-sized star ages, the central core contracts and the outer envelope expands to many times the star's original size. This changes the star from a yellow dwarf to a red giant. This will happen to our sun someday; it will swell until it encompasses even Jupiter's orbit. Red giants are many times larger than our sun, but they are also cooler.
Eventually, the core contracts as much as possible. The atoms within are packed so tightly that they cannot be further contracted. When that happens, a large amount of energy is released, ripping away the outer envelope of gas and forming a nebula of gas and dust.
The only thing left of the star is the tightly-packed core, called a white dwarf star. White dwarfs still emit heat and light, but they no longer undergo nuclear fusion. Eventually, when they radiate all their heat, they will become cold, lifeless black dwarf stars. There are no black dwarf stars today; the universe has not existed long enough for any white dwarf star to lose all of its heat.
Larger stars have a different fate. A star about three times bigger than the sun will become a red supergiant as it ages-a star many times the size of a red giant. It will run out of hydrogen, then out of helium. It will start converting helium into carbon and oxygen, just like a medium-sized star. When it runs out of helium, it will start converting the carbon and oxygen it produced into heavier elements such as sodium, magnesium, sulfur, and iron.
When such a star dies, the iron core contracts in an instant, sending out a massive shock wave. This is a supernova explosion. Supernovas appear in our sky occasionally, many times brighter than the surrounding stars. The outer layers of gas are ripped away and form an enormous nebula. The explosion also ejects heavier elements such as gold, silver, and other metals.
The core, however, is another story. In most large stars, the core contracts so tightly that even the protons in its remaining atoms are ripped away, leaving only the neutrons. This is called a neutron star. Many are only ten miles or so in diameter, but they have an extremely strong magnetic field.
In stars more than three times larger than our sun, the core is so massive that the gravitational forces pulling it together are too strong to stop. All of the star's remaining mass is crushed into a single point, or singularity, no bigger than a single atom. This is how a black hole is born.
A black hole's gravitational pull is so great that nothing, not even light, can escape. Because of this, black holes cannot be directly observed. However, the matter swirling around a black hole can indicate its position. Scientists believe that black holes lurk at the centers of most galaxies, including ours.
Without stars, the universe would be an empty place. Stars are the furnaces that forge most of the material that makes up our world, from the air we breathe to the metals we build with to the matter that makes up our bodies. Next time you see a beautiful gold necklace, handle a cast-iron skillet, or take a breath of cool air, remember-it came from the fiery heart of a star.
About the author
J Vince is managing director of thanksdarling.com - for more articles and for a range of unusual gifts including ‘name a star' visit http://www.thanksdarling.com/categories/out-of-this-world.htm
Stars begin their lives in immense clouds of gas and dust called nebulae. Nebulae contain mostly hydrogen gas, with a little helium. In most places, a nebula is often so gossamer-thin that if you walked through one, you'd never notice. However, there are some areas in a nebula where gravity causes the gas and dust to coalesce, getting more and more dense and hot.
As more and more material clumps together in these areas, the temperature inside can get extremely hot-around fifteen million degrees. The gravitational pressure is also so immense that the electrons within the atoms of hydrogen and helium are stripped, leaving only the nuclei. As the gravitational force increases, the atomic nuclei fuse. This event is called nuclear fusion. It creates an enormous outpouring of energy strong enough to counteract the crushing gravitational force. The energy pours out into space as light, heat, and electromagnetic radiation. A new star is born, and it begins to shine.
Throughout its life, a star is caught in a balancing act between the crushing forces of gravity and the explosive forces of nuclear fusion within its core. As long as there is material within the star's core that can undergo the process of nuclear fusion, the star will fight gravity and continue to shine. But when the star runs out of fuel, it dies.
Most stars are the size of our sun or smaller. Our sun is a yellow dwarf star, and it's fairly average within the universe. Stars the size of our sun usually emit light in the yellow or orange spectrum, and they live for about ten billion years.
The process of nuclear fusion converts hydrogen into helium. A star the size of our sun turns all its hydrogen into helium, and then starts converting helium into oxygen and carbon as it ages. The oxygen we breathe, and the carbon that provides the most crucial material for life on earth, was created inside a star like our sun.
As a medium-sized star ages, the central core contracts and the outer envelope expands to many times the star's original size. This changes the star from a yellow dwarf to a red giant. This will happen to our sun someday; it will swell until it encompasses even Jupiter's orbit. Red giants are many times larger than our sun, but they are also cooler.
Eventually, the core contracts as much as possible. The atoms within are packed so tightly that they cannot be further contracted. When that happens, a large amount of energy is released, ripping away the outer envelope of gas and forming a nebula of gas and dust.
The only thing left of the star is the tightly-packed core, called a white dwarf star. White dwarfs still emit heat and light, but they no longer undergo nuclear fusion. Eventually, when they radiate all their heat, they will become cold, lifeless black dwarf stars. There are no black dwarf stars today; the universe has not existed long enough for any white dwarf star to lose all of its heat.
Larger stars have a different fate. A star about three times bigger than the sun will become a red supergiant as it ages-a star many times the size of a red giant. It will run out of hydrogen, then out of helium. It will start converting helium into carbon and oxygen, just like a medium-sized star. When it runs out of helium, it will start converting the carbon and oxygen it produced into heavier elements such as sodium, magnesium, sulfur, and iron.
When such a star dies, the iron core contracts in an instant, sending out a massive shock wave. This is a supernova explosion. Supernovas appear in our sky occasionally, many times brighter than the surrounding stars. The outer layers of gas are ripped away and form an enormous nebula. The explosion also ejects heavier elements such as gold, silver, and other metals.
The core, however, is another story. In most large stars, the core contracts so tightly that even the protons in its remaining atoms are ripped away, leaving only the neutrons. This is called a neutron star. Many are only ten miles or so in diameter, but they have an extremely strong magnetic field.
In stars more than three times larger than our sun, the core is so massive that the gravitational forces pulling it together are too strong to stop. All of the star's remaining mass is crushed into a single point, or singularity, no bigger than a single atom. This is how a black hole is born.
A black hole's gravitational pull is so great that nothing, not even light, can escape. Because of this, black holes cannot be directly observed. However, the matter swirling around a black hole can indicate its position. Scientists believe that black holes lurk at the centers of most galaxies, including ours.
Without stars, the universe would be an empty place. Stars are the furnaces that forge most of the material that makes up our world, from the air we breathe to the metals we build with to the matter that makes up our bodies. Next time you see a beautiful gold necklace, handle a cast-iron skillet, or take a breath of cool air, remember-it came from the fiery heart of a star.
About the author
J Vince is managing director of thanksdarling.com - for more articles and for a range of unusual gifts including ‘name a star' visit http://www.thanksdarling.com/categories/out-of-this-world.htm
Related Tags: gifts, star, nuclear, sky, scientists, atomic, explosion, black hole, neutron, galaxies
Your Article Search Directory : Find in Articles
Recent articles in this category:
- How Hypnotherapy Can be Used on Children
Today Hypnosis can be termed as a branch of medicine which is quite unique, whereas in the past this - Confidence Workshops For Children
Every parent wants their children to be confident, happy, highly motivated and enthusiastic in order - Inspiring Children Using NLP
Neuro-Linguistic Programming (NLP) is one of the most successful therapies in psychology today. Init - Writing Term Papers
Students often tend to put off a written assignment, considering it to be a chore too formidable to - Naming In Term Paper
Give a descriptive name to each of your concept in the paper. Adhere using terms like "our approach" - Introduction Section of a Research Paper
Your introductions should not exceed more than two pages (typed, double spaced). See again the examp - Getting a Feedback of Your Term Paper is Important!
Get the feedback of your work! Finish your paper, having written it well in advance, so that you hav - The 1950's - Was Life Better?
Iconic TV shows like I Love Lucy, Dennis the Menace and My Three Sons seem to indicate that the 1950 - Online Classroom Systems Makes Home Schooling Even More Attractive
In the past it went without saying that you would send your kids to public schools. With public scho - 8 Helpful Tips For Surviving Military Basic Training
Getting through military basic training takes a lot perseverance. During this training it is best to
Most viewed articles in this category:
- Culinary Cooking Schools and What They Teach
Culinary cooking schools prepare you for a job in the culinary industry by providing you with the kn - How To Learn Spanish Quickly Without Moving To Spain
Learning Spanish is a popular pastime, as well as a serious goal for many individuals. Whether it's - How To Improve Your Life With An Accredited Online College Degree
With the information super highway raring full steam ahead, quality accredited online college degree - Online Bachelor Degree Programs Go Mainstream
The Internet has seen an explosion in online bachelor degree programs in the last five to ten years - Online Degree Program Just A Click Away
You want to go shopping, but your car is low on gas. You want to know your account balance, but do n - Online Paralegal Degree Will Open Doors
An online paralegal degree may offer the possibility of improving your chances in the legal professi - What West Point Military School Looks For In A Candidate
West Point is looking for well rounded young men and women who are good students, good athletes, and - The Importance of Effective Accounting Programs
In the past, small businesses like mom and pop stores were not required to maintain any sort of acco - California Schools Educators Retirement System And Lionstone Group Create Investment Fund
The California State Teachers' Retirement System (CSTRS) is the second largest public pension fund i - A Taste of China - Seattle Schools New Guest Teacher Shares Language and Culture of Her Native Hom
The Seattle schools have a new "guest" teacher. Zhu Dan arrived in the Seattle schools in January