Stellar Evolution 1
... • Cloud of H (70%), He (28%) gas + dust & other elements (2%) • Pressure - Gravity balance is upset Gravity > Pressure CONTRACTS Gets denser Converts gravitational PE -> KE Gets hotter • Conserves Angular Momentum Spins faster Flattens into a disk (rotation prevents contraction perpendicular to spi ...
... • Cloud of H (70%), He (28%) gas + dust & other elements (2%) • Pressure - Gravity balance is upset Gravity > Pressure CONTRACTS Gets denser Converts gravitational PE -> KE Gets hotter • Conserves Angular Momentum Spins faster Flattens into a disk (rotation prevents contraction perpendicular to spi ...
©M. Rieke 1 Correct responses in BOLDFACE. 1. Why did
... a. it was the first significant astronomical discovery by a woman b. it allowed the luminosity of these stars to be determined based on intrinsic properties, and thus their distances from their apparent brightnesses c. it allowed the astronomers of her time to test their models for the interiors of ...
... a. it was the first significant astronomical discovery by a woman b. it allowed the luminosity of these stars to be determined based on intrinsic properties, and thus their distances from their apparent brightnesses c. it allowed the astronomers of her time to test their models for the interiors of ...
Slide 1
... can reignite very suddenly, burning off the new material. • Material keeps being transferred to the white dwarf, and the process repeats, as illustrated here: ...
... can reignite very suddenly, burning off the new material. • Material keeps being transferred to the white dwarf, and the process repeats, as illustrated here: ...
(as Main Sequence Stars)?
... A star on Main Sequence has fusion of H to He in its core. How fast depends on mass of H available and rate of fusion. Mass of H in core depends on mass of star. Fusion rate is related to luminosity (fusion reactions make the radiation energy). ...
... A star on Main Sequence has fusion of H to He in its core. How fast depends on mass of H available and rate of fusion. Mass of H in core depends on mass of star. Fusion rate is related to luminosity (fusion reactions make the radiation energy). ...
giant molecular clouds
... Large, dense cluster of (yellow and red) stars in the foreground; ~ 50 million years old ...
... Large, dense cluster of (yellow and red) stars in the foreground; ~ 50 million years old ...
Introduction to Stars ppt
... Most stars fall along the main sequence – upper left to lower right. These stars fuse hydrogen into helium in their cores and have a wide range of life spans, which depend on their mass. Higher mass stars on main sequence have shorter life spans. A star has a limited supply of core hydrogen and ther ...
... Most stars fall along the main sequence – upper left to lower right. These stars fuse hydrogen into helium in their cores and have a wide range of life spans, which depend on their mass. Higher mass stars on main sequence have shorter life spans. A star has a limited supply of core hydrogen and ther ...
Astronomical Ideas Fall 2012 Homework 4 Solutions 1. Two stars
... stars correspond to the most massive stars that are still burning hydrogen on the main sequence. (More massive stars burn faster, hotter and bluer on the main sequence; less massive stars burn slower, cooler, and redder). Measuring the most massive stars that still burn H on the main sequence is a c ...
... stars correspond to the most massive stars that are still burning hydrogen on the main sequence. (More massive stars burn faster, hotter and bluer on the main sequence; less massive stars burn slower, cooler, and redder). Measuring the most massive stars that still burn H on the main sequence is a c ...
Introduction - Departamento de Astronomía
... the falling matter becames very hot and expands outwards. Finally, the star explodes and ejects the star’s outer layers into space. All that remains of is a very dense object: neutron star or black hole ...
... the falling matter becames very hot and expands outwards. Finally, the star explodes and ejects the star’s outer layers into space. All that remains of is a very dense object: neutron star or black hole ...
Mass and the Properties of Main Sequence Stars
... During the main-sequence phase, helium produced by the proton-proton chain (hydrogen burning) accumulates at the core. As a main sequence star exhausts its core hydrogen supply, its energy output is reduced. Without the thermal pressure of the hydrogen fusion, gravitation contraction continue, and t ...
... During the main-sequence phase, helium produced by the proton-proton chain (hydrogen burning) accumulates at the core. As a main sequence star exhausts its core hydrogen supply, its energy output is reduced. Without the thermal pressure of the hydrogen fusion, gravitation contraction continue, and t ...
Lecture Slides – Stars
... Initial stages (contraction onto MS, core hydrogen burning on MS) broadly similar (Radiation pressure prevents formation of very high masses, >100 solar masses) Higher masses hotter cores; core H burning is through the CNO cycle AND later stages of `burning’ (beyond triple-alpha burning of helium) ...
... Initial stages (contraction onto MS, core hydrogen burning on MS) broadly similar (Radiation pressure prevents formation of very high masses, >100 solar masses) Higher masses hotter cores; core H burning is through the CNO cycle AND later stages of `burning’ (beyond triple-alpha burning of helium) ...
WK7
... “Perhaps the greatest anomaly in this situation is the incredibly weak scientific case for the whole scenario of cosmic evolution. There can be no "experiments" or "observations" of stars evolving, in the very nature of the case, so it cannot be scientific, though it may be ...
... “Perhaps the greatest anomaly in this situation is the incredibly weak scientific case for the whole scenario of cosmic evolution. There can be no "experiments" or "observations" of stars evolving, in the very nature of the case, so it cannot be scientific, though it may be ...
Stars Notes
... A star is born when the contracting gas and dust from a nebula become so dense and hot that nuclear fusion starts ...
... A star is born when the contracting gas and dust from a nebula become so dense and hot that nuclear fusion starts ...
Great Migrations & other natural history tales
... On the similarities of chemical composition of most pop. I stars Observations show that many stars are surrounded by dust and sometimes detectable gas, in the form of the so-called debris disks or replenished dust disks, originally called Vega-type disks. The Sun has a zodiacal light disk, which is ...
... On the similarities of chemical composition of most pop. I stars Observations show that many stars are surrounded by dust and sometimes detectable gas, in the form of the so-called debris disks or replenished dust disks, originally called Vega-type disks. The Sun has a zodiacal light disk, which is ...
(0 = not at all, 10 = totally) (no wrong answers)
... diagram? When do you think we'll get to them? ...
... diagram? When do you think we'll get to them? ...
Test #4 (Ch. 13-16) ASTR 10 You have 1 hour to take the exam, and
... You have 1 hour to take the exam, and you can keep your copy of the test once you’re done. A list of answers to this exam will post to the course website next week, so you can have feedback on the exam before the final. 1. Which two processes can generate energy to help a star maintain its internal ...
... You have 1 hour to take the exam, and you can keep your copy of the test once you’re done. A list of answers to this exam will post to the course website next week, so you can have feedback on the exam before the final. 1. Which two processes can generate energy to help a star maintain its internal ...
sep04 neutrinos - Charles J Horowitz
... is just above frame and interacts with its binary companion star ...
... is just above frame and interacts with its binary companion star ...
Teacher Guide - Astronomy Outreach at UT Austin
... Page the photon reporter: an energetic but sensitive photon journalist who is interviewing the Sun for her column in the Local Group Times. Sol the white dwarf: a kind and friendly star, our Sun at the end of his life. Sol used to be a yellow star. This interview takes place about 5 billion years in ...
... Page the photon reporter: an energetic but sensitive photon journalist who is interviewing the Sun for her column in the Local Group Times. Sol the white dwarf: a kind and friendly star, our Sun at the end of his life. Sol used to be a yellow star. This interview takes place about 5 billion years in ...
Neutron Stars and Black Holes
... disperse in the Galactic disk more, making them more unlikely to affect us. •! That said, one of our very, very close stars is Sirius (9 lyrs!), which is a white dwarf and main sequence A star companion. ...
... disperse in the Galactic disk more, making them more unlikely to affect us. •! That said, one of our very, very close stars is Sirius (9 lyrs!), which is a white dwarf and main sequence A star companion. ...
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.