Red Giants and White Dwarfs
... • With no energy source, the core of the star resumes its collapse… • As it collapses, gravitational energy is again converted to thermal energy… • This heat allows fusion to occur in a shell of material surrounding the core… • Due to the higher central temperature, the star’s luminosity is greater ...
... • With no energy source, the core of the star resumes its collapse… • As it collapses, gravitational energy is again converted to thermal energy… • This heat allows fusion to occur in a shell of material surrounding the core… • Due to the higher central temperature, the star’s luminosity is greater ...
Stellar Evolution - FSU High Energy Physics
... • Outer Hydrogen envelope, i.e. planetary nebula eventually drifts off • Hot remnant core is a white dwarf • No more support from burning fuel. • Thermal motion of the ions will become less important and eventually degenerate ...
... • Outer Hydrogen envelope, i.e. planetary nebula eventually drifts off • Hot remnant core is a white dwarf • No more support from burning fuel. • Thermal motion of the ions will become less important and eventually degenerate ...
A Red Giant - Cloudfront.net
... Stars like our Sun Stars with masses similar to our Sun fuse at a rate that allows them to “live” as mainsequence stars for about 10 billion years. Then they run out of Hydrogen in their core Hydrostatic Equilibrium is lost… They Shrink a bit And begin to fuse Hydrogen into Helium in a shell outsid ...
... Stars like our Sun Stars with masses similar to our Sun fuse at a rate that allows them to “live” as mainsequence stars for about 10 billion years. Then they run out of Hydrogen in their core Hydrostatic Equilibrium is lost… They Shrink a bit And begin to fuse Hydrogen into Helium in a shell outsid ...
tire
... 7. An object whose gravity is so strong that the escape speed exceeds the speed of light. 8. A type of yellow supergiant pulsating star. 9. A starlike object that is not massive enough to ignite hydrogen fusion in its core. 10. A plot of the luminosity (or absolute magnitude) of stars versus their s ...
... 7. An object whose gravity is so strong that the escape speed exceeds the speed of light. 8. A type of yellow supergiant pulsating star. 9. A starlike object that is not massive enough to ignite hydrogen fusion in its core. 10. A plot of the luminosity (or absolute magnitude) of stars versus their s ...
When Stars Blow Up
... •At the base of the accreted layer, electrons become degenerate •When the temperature reaches a few MK, fusion begins •Degenerate fusion is a runaway. •All the H fuses to He and heavier elements in a soundcrossing time (a few minutes) •The star increases in brightness ~ 10,000 times •Most of the mat ...
... •At the base of the accreted layer, electrons become degenerate •When the temperature reaches a few MK, fusion begins •Degenerate fusion is a runaway. •All the H fuses to He and heavier elements in a soundcrossing time (a few minutes) •The star increases in brightness ~ 10,000 times •Most of the mat ...
Slide 1
... Black Holes • Neutron stars will eventually collapse because of gravity. • They are then squeezed into a very small area and become very dense with a huge gravitational pull. • This pull sucks in everything around it. • http://www.seed.slb.com/en/scictr/lab/byo_star/in ...
... Black Holes • Neutron stars will eventually collapse because of gravity. • They are then squeezed into a very small area and become very dense with a huge gravitational pull. • This pull sucks in everything around it. • http://www.seed.slb.com/en/scictr/lab/byo_star/in ...
Introduction to Astronomy
... Sizes of Main-Sequence Stars Hottest stars are actually somewhat larger ...
... Sizes of Main-Sequence Stars Hottest stars are actually somewhat larger ...
Stellar Evolution
... • Gravity causes the cloud to collapse and condense • Temperatures begin to increase = Glows • Fusion begins at VERY high temps. (Some of the extra gas and dust may form planets) ...
... • Gravity causes the cloud to collapse and condense • Temperatures begin to increase = Glows • Fusion begins at VERY high temps. (Some of the extra gas and dust may form planets) ...
Chapter 27.2
... thousands of times for a few days. • Believed to be caused by gas (from a companion star) buildup on the white dwarf’s surface. ...
... thousands of times for a few days. • Believed to be caused by gas (from a companion star) buildup on the white dwarf’s surface. ...
Stellar Evolution
... Formation of Stars • Begins with interstellar gas and dust called a nebula • Collapses on self as a result of gravity • Rotates and flattens with hot condensed object at center called a protostar ...
... Formation of Stars • Begins with interstellar gas and dust called a nebula • Collapses on self as a result of gravity • Rotates and flattens with hot condensed object at center called a protostar ...
Stellar evolution
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.Stellar evolution is not studied by observing the life of a single star, as most stellar changes occur too slowly to be detected, even over many centuries. Instead, astrophysicists come to understand how stars evolve by observing numerous stars at various points in their lifetime, and by simulating stellar structure using computer models.In June 2015, astronomers reported evidence for Population III stars in the Cosmos Redshift 7 galaxy at z = 6.60. Such stars are likely to have existed in the very early universe (i.e., at high redshift), and may have started the production of chemical elements heavier than hydrogen that are needed for the later formation of planets and life as we know it.