- published: 22 Apr 2015
- views: 7482
Stellar evolution is the process by which a star changes during its lifetime. Depending on the mass of the star, this lifetime ranges from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the age of the universe. The table shows the lifetimes of stars as a function of their masses. All stars are born from collapsing clouds of gas and dust, often called nebulae or molecular clouds. Over the course of millions of years, these protostars settle down into a state of equilibrium, becoming what is known as a main-sequence star.
Nuclear fusion powers a star for most of its life. Initially the energy is generated by the fusion of hydrogen atoms at the core of the main-sequence star. Later, as the preponderance of atoms at the core becomes helium, stars like the Sun begin to fuse hydrogen along a spherical shell surrounding the core. This process causes the star to gradually grow in size, passing through the subgiant stage until it reaches the red giant phase. Stars with at least half the mass of the Sun can also begin to generate energy through the fusion of helium at their core, whereas more-massive stars can fuse heavier elements along a series of concentric shells. Once a star like the Sun has exhausted its nuclear fuel, its core collapses into a dense white dwarf and the outer layers are expelled as a planetary nebula. Stars with around ten or more times the mass of the Sun can explode in a supernova as their inert iron cores collapse into an extremely dense neutron star or black hole. Although the universe is not old enough for any of the smallest red dwarfs to have reached the end of their lives, stellar models suggest they will slowly become brighter and hotter before running out of hydrogen fuel and becoming low-mass white dwarfs.
Life cycle may refer to:
Crash Course (also known as Driving Academy) is a 1988 made for television teen film directed by Oz Scott.
Crash Course centers on a group of high schoolers in a driver’s education class; many for the second or third time. The recently divorced teacher, super-passive Larry Pearl, is on thin ice with the football fanatic principal, Principal Paulson, who is being pressured by the district superintendent to raise driver’s education completion rates or lose his coveted football program. With this in mind, Principal Paulson and his assistant, with a secret desire for his job, Abner Frasier, hire an outside driver’s education instructor with a very tough reputation, Edna Savage, aka E.W. Savage, who quickly takes control of the class.
The plot focuses mostly on the students and their interactions with their teachers and each other. In the beginning, Rico is the loner with just a few friends, Chadley is the bookish nerd with few friends who longs to be cool and also longs to be a part of Vanessa’s life who is the young, friendly and attractive girl who had to fake her mother’s signature on her driver’s education permission slip. Kichi is the hip-hop Asian kid who often raps what he has to say and constantly flirts with Maria, the rich foreign girl who thinks that the right-of-way on the roadways always goes to (insert awesomely fake foreign Latino accent) “my father’s limo”. Finally you have stereotypical football meathead J.J., who needs to pass his English exam to keep his eligibility and constantly asks out and gets rejected by Alice, the tomboy whose father owns “Santini & Son” Concrete Company. Alice is portrayed as being the “son” her father wanted.
A fast draw animated presentation which describes the process of star creation. 2015 © Squid Studios. All Rights Reserved. Music: Chris Zabriskie - Cylinder One
A beautiful video showing the life and death of a star. Music and video credits listed at the end of the video. For a full list of credits, please contact webpage admin
Planets Song for Kids / Solar System Song /Evolution of a Star Learn about the evolution of a star and how it's created with this fun, animated, catchy music video. And don't forget to sing along! Facebook: https://www.facebook.com/kidslearningtube Subscribe: http://www.youtube.com/c/kidslearningtube Tweet Us: https://twitter.com/learningtube Instagram: https://instagram.com/kidslearningtube Add us on Google+: https://plus.google.com/+KidsLearning... Music: Copyright 2015 Kids Learning Tube Video: Copyright 2015 Kids Learning Tube LYRICS: This is the Stellar Evolution of a star in the Universe A Nebula is the beginning of a star before its birth The star names you will encounter Are some basic different stages in the evolution of a star and all it’s basic changes I’m a Molecul...
stellar evolution - the life and death of a star
This video explains the life cycle of stars from nebular to giant to white dwarf (or supernova for stars more massive than our Sun.)
Today we are talking about the life -- and death -- of stars. Low mass stars live a long time, fusing all their hydrogen into helium over a trillion years. More massive stars like the Sun live shorter lives. They fuse hydrogen into helium, and eventually helium into carbon (and also some oxygen and neon). When this happens they expand, get brighter, and cool off, becoming red giants. They lose most of their mass, exposing their cores, and then cool off over many billions of years. Crash Course Astronomy posters now available at DFTBA: http://store.dftba.com/products/crashcourse-astronomy-poster -- Table of Contents Low Mass Stars Live a Long Time 0:57 Larger Stars (Like Our Sun) Live Shorter Lives 3:10 Fueled By Fusion 3:58 How They Turn Into Red Giants 5:45 -- PBS Digital Studios: ht...
A fast draw animated presentation which describes the process of star creation. 2015 © Squid Studios. All Rights Reserved. Music: Chris Zabriskie - Cylinder One
A beautiful video showing the life and death of a star. Music and video credits listed at the end of the video. For a full list of credits, please contact webpage admin
Planets Song for Kids / Solar System Song /Evolution of a Star Learn about the evolution of a star and how it's created with this fun, animated, catchy music video. And don't forget to sing along! Facebook: https://www.facebook.com/kidslearningtube Subscribe: http://www.youtube.com/c/kidslearningtube Tweet Us: https://twitter.com/learningtube Instagram: https://instagram.com/kidslearningtube Add us on Google+: https://plus.google.com/+KidsLearning... Music: Copyright 2015 Kids Learning Tube Video: Copyright 2015 Kids Learning Tube LYRICS: This is the Stellar Evolution of a star in the Universe A Nebula is the beginning of a star before its birth The star names you will encounter Are some basic different stages in the evolution of a star and all it’s basic changes I’m a Molecul...
stellar evolution - the life and death of a star
This video explains the life cycle of stars from nebular to giant to white dwarf (or supernova for stars more massive than our Sun.)
Today we are talking about the life -- and death -- of stars. Low mass stars live a long time, fusing all their hydrogen into helium over a trillion years. More massive stars like the Sun live shorter lives. They fuse hydrogen into helium, and eventually helium into carbon (and also some oxygen and neon). When this happens they expand, get brighter, and cool off, becoming red giants. They lose most of their mass, exposing their cores, and then cool off over many billions of years. Crash Course Astronomy posters now available at DFTBA: http://store.dftba.com/products/crashcourse-astronomy-poster -- Table of Contents Low Mass Stars Live a Long Time 0:57 Larger Stars (Like Our Sun) Live Shorter Lives 3:10 Fueled By Fusion 3:58 How They Turn Into Red Giants 5:45 -- PBS Digital Studios: ht...
Dr. Charles Jackson points out the problems in the story of stellar evolution.
Dr. Charles Jackson points out the problems in the story of stellar evolution.
-- Watch live at https://www.twitch.tv/skylias