Introduction to Stellar Evolution
... 3) Start of main sequence (hydrogen burning) 4) End of main sequence (core is now all helium) 5) Climbing giant branch hydrogen burning in shell around inert helium core hydrogen envelope swells up 6) Helium ignition in a “flash” 7) Helium burning to carbon/oxygen ...
... 3) Start of main sequence (hydrogen burning) 4) End of main sequence (core is now all helium) 5) Climbing giant branch hydrogen burning in shell around inert helium core hydrogen envelope swells up 6) Helium ignition in a “flash” 7) Helium burning to carbon/oxygen ...
Lecture 18: Supernovae
... Nuclei photodisintegrate into He, p, & n Protons & electrons combine into neutrons and neutrinos, neutrinos escape and carry off energy Makes the core collapse faster, as the insufficient pressure is decreased further ...
... Nuclei photodisintegrate into He, p, & n Protons & electrons combine into neutrons and neutrinos, neutrinos escape and carry off energy Makes the core collapse faster, as the insufficient pressure is decreased further ...
White Dwarf Stars
... • Stellar cores that are more massive than about 3 M☼ have too strong a gravitational field to be supported by even neutron degeneracy pressure → black holes. • The more massive a black hole, the larger its event horizon. • Stellar mass black holes are detected via their X-ray radiation. • A black h ...
... • Stellar cores that are more massive than about 3 M☼ have too strong a gravitational field to be supported by even neutron degeneracy pressure → black holes. • The more massive a black hole, the larger its event horizon. • Stellar mass black holes are detected via their X-ray radiation. • A black h ...
Life Cycle of Stars
... – Star joins the main sequence • 90% of stars are here • Nuclear fusion = Hydrogen into Helium • Mass of star determines location on main sequence ...
... – Star joins the main sequence • 90% of stars are here • Nuclear fusion = Hydrogen into Helium • Mass of star determines location on main sequence ...
File - Mr. Goodyear Astronomy
... He in the protonproton cycle. 90% of stars are main sequence stage. Stars are said to be in Hydrostatic Equilibrium: energy output = gravitational pull inward (known as hydrogen burning stage) Stars like our sun last 10 billion years as a main sequence ...
... He in the protonproton cycle. 90% of stars are main sequence stage. Stars are said to be in Hydrostatic Equilibrium: energy output = gravitational pull inward (known as hydrogen burning stage) Stars like our sun last 10 billion years as a main sequence ...
Stars and Black Holes: Stars A star is a massive, luminous ball of
... A star is a massive, luminous ball of ____________. A star shines because nuclear fusion in its core releases energy that radiates into space. Although in the sky, stars all appear _____________ they are actually all different colours. The ______________ of a star depends on the amount of energy it ...
... A star is a massive, luminous ball of ____________. A star shines because nuclear fusion in its core releases energy that radiates into space. Although in the sky, stars all appear _____________ they are actually all different colours. The ______________ of a star depends on the amount of energy it ...
The Life Cycle of a Star
... the star has ignited, it becomes a main sequence star. Main Sequence stars fuse hydrogen to form helium, releasing enormous amounts of energy. It takes about 10 billion years to consume all the hydrogen in a Main Sequence star. ...
... the star has ignited, it becomes a main sequence star. Main Sequence stars fuse hydrogen to form helium, releasing enormous amounts of energy. It takes about 10 billion years to consume all the hydrogen in a Main Sequence star. ...
Solving the Mystery of Massive Star Birth
... collapse of the cloud, which begins to shrink under the pull of its own gravity. As the cloud gets smaller, it gets clumpy. The clumps may eventually become so compact that they begin to heat up, growing hotter and hotter, until eventually they begin “burning” at their core. When the temperature at ...
... collapse of the cloud, which begins to shrink under the pull of its own gravity. As the cloud gets smaller, it gets clumpy. The clumps may eventually become so compact that they begin to heat up, growing hotter and hotter, until eventually they begin “burning” at their core. When the temperature at ...
Stars Notes
... Fusion of hydrogen slows Core starts to contract Outer layers expand Core reaches temperatures high enough to spark the fusion into carbon (200,000,000°C) ...
... Fusion of hydrogen slows Core starts to contract Outer layers expand Core reaches temperatures high enough to spark the fusion into carbon (200,000,000°C) ...
Life Cycle of Stars
... How Stars End • Stars burn until they use all their nuclear fuel. • Different size stars evolve differently. • The larger a star, the hotter, brighter and shorter lived it is. ...
... How Stars End • Stars burn until they use all their nuclear fuel. • Different size stars evolve differently. • The larger a star, the hotter, brighter and shorter lived it is. ...
The Hidden Lives of Galaxies NSTA 2001
... Materials for Life Cycles of Stars This presentation, and other materials on the Life Cycles of Stars, are available on the Imagine the Universe! web site at: http://imagine.gsfc.nasa.gov/docs/teachers/lifecycles/stars.html ...
... Materials for Life Cycles of Stars This presentation, and other materials on the Life Cycles of Stars, are available on the Imagine the Universe! web site at: http://imagine.gsfc.nasa.gov/docs/teachers/lifecycles/stars.html ...
Death of Stars - Astronomy @ Walton High School
... 1 Similar to a nova where a dwarf takes material from a giant. This time the explosion destroys the dwarf. Typically this takes place when the mass of the white dwarf is over 1.4 solar masses. 2 When a star has a mass greater than 8 solar masses. The red giant swells so much it collapses in on itsel ...
... 1 Similar to a nova where a dwarf takes material from a giant. This time the explosion destroys the dwarf. Typically this takes place when the mass of the white dwarf is over 1.4 solar masses. 2 When a star has a mass greater than 8 solar masses. The red giant swells so much it collapses in on itsel ...
The Death of a Low Mass Star
... – Carbon and oxygen brought to the surface – In consequence, molecular absorption bands often seen in the spectra of AGB stars – Soot coccoons may also form around such ...
... – Carbon and oxygen brought to the surface – In consequence, molecular absorption bands often seen in the spectra of AGB stars – Soot coccoons may also form around such ...
H-R Diagrams
... Supergiants on the HR Diagram • As the shells of fusion around the core increase in number: – thermal pressure overbalances the lower gravity in the outer layers – the surface of the star expands – the surface of the star cools ...
... Supergiants on the HR Diagram • As the shells of fusion around the core increase in number: – thermal pressure overbalances the lower gravity in the outer layers – the surface of the star expands – the surface of the star cools ...
White Dwarfs, Neutron Stars, and Black Holes
... Masses between 0.4 and 8 solar masses. The envelope of the red giant becomes unstable (thermal pulses)and is expelled. The nebula that results is called a planetary nebula. Fluorescence occurs only if the temperature of the star inside the expelled material is least 25,000 K. Eventually, a star will ...
... Masses between 0.4 and 8 solar masses. The envelope of the red giant becomes unstable (thermal pulses)and is expelled. The nebula that results is called a planetary nebula. Fluorescence occurs only if the temperature of the star inside the expelled material is least 25,000 K. Eventually, a star will ...
Study Guide
... main sequence star - as soon as fusion starts, the star is in this stage fusing hydrogen into helium Protostar – cloud of gas and dust that is now spinning Supergiant – similar to a giant but does not stop with carbon fusion it continues fusion to the dead end element Black hole - spinning causes th ...
... main sequence star - as soon as fusion starts, the star is in this stage fusing hydrogen into helium Protostar – cloud of gas and dust that is now spinning Supergiant – similar to a giant but does not stop with carbon fusion it continues fusion to the dead end element Black hole - spinning causes th ...
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.