The Milky Way - 清華大學物理系歡迎頁 Welcome to
... Guidepost Stars form from the interstellar medium and reach stability fusing hydrogen in their cores. This chapter is about the long, stable middle age of stars on the main sequence and their old age as they swell to become giant stars. Here you will answer three essential questions: • What happens ...
... Guidepost Stars form from the interstellar medium and reach stability fusing hydrogen in their cores. This chapter is about the long, stable middle age of stars on the main sequence and their old age as they swell to become giant stars. Here you will answer three essential questions: • What happens ...
Young Stars
... •Lighter than 0.08 – they don’t get hot enough for fusion •Heavier than 150 – they burn so furiously they blow off their outer layers •Light stars much more common than heavy ones •Objects lighter than 0.08 MSun are called Brown brown Dwarf dwarfs ...
... •Lighter than 0.08 – they don’t get hot enough for fusion •Heavier than 150 – they burn so furiously they blow off their outer layers •Light stars much more common than heavy ones •Objects lighter than 0.08 MSun are called Brown brown Dwarf dwarfs ...
Open clusters
... Review from last time: from observations of nearby stars, we can determine: distance to star apparent brightness luminosity spectral type temperature (for binary systems: mass) radius ...
... Review from last time: from observations of nearby stars, we can determine: distance to star apparent brightness luminosity spectral type temperature (for binary systems: mass) radius ...
We Are All Stardust: Nuclear Physics in the Cosmos
... of helium burning) He-burning shell He layer (the ashes of hydrogen burning) H-burning shell Hydrogen-rich envelope Core never gets hot enough to burn carbon ...
... of helium burning) He-burning shell He layer (the ashes of hydrogen burning) H-burning shell Hydrogen-rich envelope Core never gets hot enough to burn carbon ...
HW9_Answers
... bound together than any of the other 91 elements. As a result, when iron is fused into some other heavier element the fusion process does not release energy. The resulting, new nuleus is more spread out, which means it has a higher potential energy than iron does. So some of the energy in the fusion ...
... bound together than any of the other 91 elements. As a result, when iron is fused into some other heavier element the fusion process does not release energy. The resulting, new nuleus is more spread out, which means it has a higher potential energy than iron does. So some of the energy in the fusion ...
Star Life Cycle
... Within a nebula, there are varying regions when gravity causes this dust and gas to “clump” together. As these “clumps” gather more atoms (mass), their gravitational attraction to other atoms increases, pulling more atoms into the “clump.” ...
... Within a nebula, there are varying regions when gravity causes this dust and gas to “clump” together. As these “clumps” gather more atoms (mass), their gravitational attraction to other atoms increases, pulling more atoms into the “clump.” ...
THE LIFE CYCLE OF A STAR
... a million years before exploding as supernovae. The faintest stars are the red dwarfs, less than onethousandth the brightness of the Sun. The smallest mass possible for a star is about 8% that of the Sun (80 times the mass of the planet Jupiter), otherwise nuclear reactions do not take place. Object ...
... a million years before exploding as supernovae. The faintest stars are the red dwarfs, less than onethousandth the brightness of the Sun. The smallest mass possible for a star is about 8% that of the Sun (80 times the mass of the planet Jupiter), otherwise nuclear reactions do not take place. Object ...
Why Is the Sun a Star
... energy! Any object can become a star if it becomes massive enough. How massive is enough? If Jupiter were about 75 times more massive its gravity would increase enough for nuclear fusion to begin and we would have a second Sun in our solar system! Interestingly, scientists recently discovered a new ...
... energy! Any object can become a star if it becomes massive enough. How massive is enough? If Jupiter were about 75 times more massive its gravity would increase enough for nuclear fusion to begin and we would have a second Sun in our solar system! Interestingly, scientists recently discovered a new ...
ASTRONOMY 120
... The increased gas pressure pushes on the outer part of the star, expanding it. As the gas in the outer layers expands and becomes less dense, it cools down, and the star’s color changes to red. ...
... The increased gas pressure pushes on the outer part of the star, expanding it. As the gas in the outer layers expands and becomes less dense, it cools down, and the star’s color changes to red. ...
Main-sequence stars - Stellar Populations
... Off the Main Sequence • Stellar properties depend on both mass and age: those that have finished fusing H to He in their cores are no longer on the main sequence ...
... Off the Main Sequence • Stellar properties depend on both mass and age: those that have finished fusing H to He in their cores are no longer on the main sequence ...
Stars & Galaxies
... professional development ONLY; and may not be used for other purposes, in whole or part, without the expressed written permission of their ESC-TESCCC coordinator for the region handling your subscription. TESCCC grants subscribers the right to edit this multimedia presentation for intra-district pro ...
... professional development ONLY; and may not be used for other purposes, in whole or part, without the expressed written permission of their ESC-TESCCC coordinator for the region handling your subscription. TESCCC grants subscribers the right to edit this multimedia presentation for intra-district pro ...
Starry Starry Night Vocabulary
... Artist: A person who creates art such as paintings, drawings or sculpture. Astronomy: The study of objects outside the earth’s atmosphere, including planets and stars. Author: A person who writes a story or a book. Aztecs: An ancient civilization in Mexico. Aztecs studies the stars, noticed that the ...
... Artist: A person who creates art such as paintings, drawings or sculpture. Astronomy: The study of objects outside the earth’s atmosphere, including planets and stars. Author: A person who writes a story or a book. Aztecs: An ancient civilization in Mexico. Aztecs studies the stars, noticed that the ...
The Stars
... 3. compare and contrast the function and design of different telescopes (refracting, reflecting, radio). 4. describe the process by which the sun generates energy. 5. describe the internal structure of the sun. 6. define the solar wind, and indicate its effects on the planets. 7. describe three majo ...
... 3. compare and contrast the function and design of different telescopes (refracting, reflecting, radio). 4. describe the process by which the sun generates energy. 5. describe the internal structure of the sun. 6. define the solar wind, and indicate its effects on the planets. 7. describe three majo ...
Stars - Independence High School
... • Star Formation- Cloud of interstellar gas called a Nebula which forms a Protostar • Protostar becomes hot enough for fusion to begin and become a star ...
... • Star Formation- Cloud of interstellar gas called a Nebula which forms a Protostar • Protostar becomes hot enough for fusion to begin and become a star ...
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.