The Virial Theorem
... • The virial theorem only applies to a system of par1cles in equilibrium. Therefore can not apply to collapsing interstellar clouds! • The virial theorem can be used to state approximately half of the ...
... • The virial theorem only applies to a system of par1cles in equilibrium. Therefore can not apply to collapsing interstellar clouds! • The virial theorem can be used to state approximately half of the ...
white dwarfs.
... c) the carbon core detonates, and it explodes as a Type I supernova. d) helium builds up in the core, while the hydrogen-burning ...
... c) the carbon core detonates, and it explodes as a Type I supernova. d) helium builds up in the core, while the hydrogen-burning ...
Surveys of Stars, The interstellar medium
... The Interstellar Medium absorbs light more strongly at shorter wavelengths. ...
... The Interstellar Medium absorbs light more strongly at shorter wavelengths. ...
Eksamination in FY2450 Astrophysics Wednesday June 8
... because more and more of the atoms become excited, so that finally no atoms remain in the lower level. Atoms can bind into molecules only in the atmospheres of the coolest stars. The higher the excitation energy of the atomic transition, the higher the temperature where the spectral line appears. Fo ...
... because more and more of the atoms become excited, so that finally no atoms remain in the lower level. Atoms can bind into molecules only in the atmospheres of the coolest stars. The higher the excitation energy of the atomic transition, the higher the temperature where the spectral line appears. Fo ...
Measuring Stars
... •Composition is almost always the same •Mass is difficult to measure •Radius can be deduced from Luminosity and Temperature ...
... •Composition is almost always the same •Mass is difficult to measure •Radius can be deduced from Luminosity and Temperature ...
9. Lectures on Star Formation.
... •Dust surrounding stars can reflect the light of the stars and make reflection nebula (nebula=cloud). •Very dense cloud of dust can hide stars behind it and is called “dark nebula.” •Warm dust ( a few 100 degrees) can be observed glowing in the IR. •Gas produces interstellar absorption lines in st ...
... •Dust surrounding stars can reflect the light of the stars and make reflection nebula (nebula=cloud). •Very dense cloud of dust can hide stars behind it and is called “dark nebula.” •Warm dust ( a few 100 degrees) can be observed glowing in the IR. •Gas produces interstellar absorption lines in st ...
Ast 405, Pulsating Stars The following is based Chapter 14 of the
... • 12. Contracting gases heat up and expanding gases cool down according to the ideal gas law. This is what is to be expected during an adiabatic change. But pulsating stars generally are brightest when they are expanding through their equilbrium radius. This is the phase lag for classical Cepheids ...
... • 12. Contracting gases heat up and expanding gases cool down according to the ideal gas law. This is what is to be expected during an adiabatic change. But pulsating stars generally are brightest when they are expanding through their equilbrium radius. This is the phase lag for classical Cepheids ...
PDF copy
... The discovery of the mechanism of fasting and feasting process is the breakthrough that many were looking forward to and given important inputs for further theoretical understanding of these binaries. Says Dr Bhalerao: “This allows us to better understand how massive stars form, to study how binarie ...
... The discovery of the mechanism of fasting and feasting process is the breakthrough that many were looking forward to and given important inputs for further theoretical understanding of these binaries. Says Dr Bhalerao: “This allows us to better understand how massive stars form, to study how binarie ...
Making H-R Diagrams - PLC-METS
... temperatures, different brightness, different sizes, and different distances from Earth. A star’s mass dictates how bright it will be, how long it will live, its temperature and its size. The Sun is the center of our solar system and is very bright to us on Earth. Other stars in our galaxy are brigh ...
... temperatures, different brightness, different sizes, and different distances from Earth. A star’s mass dictates how bright it will be, how long it will live, its temperature and its size. The Sun is the center of our solar system and is very bright to us on Earth. Other stars in our galaxy are brigh ...
Scale of Apparent Magnitudes of Celestial Objects
... The modern system is not limited to six levels, and includes objects visible only to the most powerful telescopes, as well as planets and daytime objects such as the Sun and the Moon. The step size between adjacent magnitudes is now a factor of 2.512, so a magnitude 1 star has an apparent visual mag ...
... The modern system is not limited to six levels, and includes objects visible only to the most powerful telescopes, as well as planets and daytime objects such as the Sun and the Moon. The step size between adjacent magnitudes is now a factor of 2.512, so a magnitude 1 star has an apparent visual mag ...
Giant Stars
... Red Giant Core Helium Burning •At 100 million K, the helium core in a red giant star ignites •Suddenly for light stars (< 3 MSun) •Gradually for heavy stars (> 3 MSun) •New heat source in core •It expands and cools •Hydrogen, still burning in a shell, burns more slowly now •Less heat going into h ...
... Red Giant Core Helium Burning •At 100 million K, the helium core in a red giant star ignites •Suddenly for light stars (< 3 MSun) •Gradually for heavy stars (> 3 MSun) •New heat source in core •It expands and cools •Hydrogen, still burning in a shell, burns more slowly now •Less heat going into h ...
Level 2 Science (90764) 2011 Assessment Schedule
... • Sirius A is a blue / white star in the main sequence. • Sirius B is a white dwarf. • Sirius A is much hotter star, burning fuel more rapidly. • Sirius A is more luminous due to the faster fuel burning rate and size. • Luminosity is the amount of light being given off by the star. • White dwarf is ...
... • Sirius A is a blue / white star in the main sequence. • Sirius B is a white dwarf. • Sirius A is much hotter star, burning fuel more rapidly. • Sirius A is more luminous due to the faster fuel burning rate and size. • Luminosity is the amount of light being given off by the star. • White dwarf is ...
Big Bang Theory
... First elements formed were hydrogen, helium and deuterium (isotope of hydrogen). ...
... First elements formed were hydrogen, helium and deuterium (isotope of hydrogen). ...
chapter8
... The Size (Radius) of a Star We already know: flux increases with surface temperature (~ T4); hotter stars are brighter. ...
... The Size (Radius) of a Star We already know: flux increases with surface temperature (~ T4); hotter stars are brighter. ...
Universe 8e Lecture Chapter 17 Nature of Stars
... HR Diagram I expect you to know which of the gray sequences is ...
... HR Diagram I expect you to know which of the gray sequences is ...
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.