Stars, Galaxies, and the Universe Section 1 Section 1
... from Earth, is caused by the movement of Earth. • The stars seem as though they are moving counterclockwise around a central star called Polaris, the North Star. Polaris is almost directly above the North Pole, and thus the star does not appear to move much. • Earth’s revolution around the sun cause ...
... from Earth, is caused by the movement of Earth. • The stars seem as though they are moving counterclockwise around a central star called Polaris, the North Star. Polaris is almost directly above the North Pole, and thus the star does not appear to move much. • Earth’s revolution around the sun cause ...
Presentation (PowerPoint File)
... Problem: How do stars form--by gravitational collapse, gravitational accretion, or stellar mergers? Prospect: May require more computer power to resolve this, since calculation of formation of even one star is a challenge. Problem: How do massive stars form in the face of radiation ...
... Problem: How do stars form--by gravitational collapse, gravitational accretion, or stellar mergers? Prospect: May require more computer power to resolve this, since calculation of formation of even one star is a challenge. Problem: How do massive stars form in the face of radiation ...
stars-notes
... object when viewed from different locations. • Astronomers use parallax and trigonometry to find the actual distance to stars that are close to Earth. ...
... object when viewed from different locations. • Astronomers use parallax and trigonometry to find the actual distance to stars that are close to Earth. ...
The Properties of Stars Early in its history, the universe organized
... plots are now known as Hertzsprung-Russell diagrams. Because of the StefanBoltzmann law, these diagrams also contain information about the sizes of the stars. HR diagrams will be useful in the next reading, when we discuss stellar evolution. Stars are not scattered evenly over the H-R diagram; inste ...
... plots are now known as Hertzsprung-Russell diagrams. Because of the StefanBoltzmann law, these diagrams also contain information about the sizes of the stars. HR diagrams will be useful in the next reading, when we discuss stellar evolution. Stars are not scattered evenly over the H-R diagram; inste ...
PH607lec10
... As we look out into the night sky, we see an enormous number of stars fairly uniformly distributed across the sky Additionally, on a clear, DARK night we see the Milky Way – a faint band of light cut by a dark rift stretching around the sky(see below) In 1610, Galileo (1564-1642) pointed his telesco ...
... As we look out into the night sky, we see an enormous number of stars fairly uniformly distributed across the sky Additionally, on a clear, DARK night we see the Milky Way – a faint band of light cut by a dark rift stretching around the sky(see below) In 1610, Galileo (1564-1642) pointed his telesco ...
THE INNER CORE OF A NEUTRON STAR Part 1
... Abstract: Neutron stars are formed by super compaction that result from the gravitational collapse of a massive star after a supernova. Neutron star composition makes it so heavy that its density is at least twice the mass of Earth’s Sun. Current thinking subscribes to the possibility that a neutron ...
... Abstract: Neutron stars are formed by super compaction that result from the gravitational collapse of a massive star after a supernova. Neutron star composition makes it so heavy that its density is at least twice the mass of Earth’s Sun. Current thinking subscribes to the possibility that a neutron ...
The Life Cycle of Spiral Arm Galaxies
... As a star goes supernova, it releases a great amount of energy (light) and also ejects a massive amount of matter (galactic cosmic rays), which are charged particles such as protons and pieces of ...
... As a star goes supernova, it releases a great amount of energy (light) and also ejects a massive amount of matter (galactic cosmic rays), which are charged particles such as protons and pieces of ...
The Chemical Composition of Stars in Open Clusters
... same problems are studied with entirely different and independent techniques, secondly because the abundance determi nations of stars probably are more accu rate than those of H 11 regions, and thirdly because the stars allow studies of a number of interesting elements that are not represented in th ...
... same problems are studied with entirely different and independent techniques, secondly because the abundance determi nations of stars probably are more accu rate than those of H 11 regions, and thirdly because the stars allow studies of a number of interesting elements that are not represented in th ...
Problem Set 2
... Show that at radius R, the number of stars per unit area – the surface density – of type S is Σ(R, S) = 2n(0, 0, S)hz (S) exp[−R/hR (S)]. If each star has lmuinosity L(S), the surface brightness I(R, S) = L(S)Σ(R, S). Assuming that hR and hz are the same for all S, show that the disk’s total luminos ...
... Show that at radius R, the number of stars per unit area – the surface density – of type S is Σ(R, S) = 2n(0, 0, S)hz (S) exp[−R/hR (S)]. If each star has lmuinosity L(S), the surface brightness I(R, S) = L(S)Σ(R, S). Assuming that hR and hz are the same for all S, show that the disk’s total luminos ...
Topic 7_2_Ext B__Nuclear stability
... will have no more radiation pressure to oppose gravity. It will collapse (due to gravity), and its complex iron nuclei will decay into ALL NEUTRONS! FYI: This is called the IRON CATASTROPHE. ...
... will have no more radiation pressure to oppose gravity. It will collapse (due to gravity), and its complex iron nuclei will decay into ALL NEUTRONS! FYI: This is called the IRON CATASTROPHE. ...
STARS AND PLANETS: A NEW SET OF MIDDLE SCHOOL
... again use a scale factor of 1 to 10 billion. Working individually of in small groups, students determine the scaled sizes of exotic objects such as red giants, white dwarfs, and black holes. They then compare the sizes of dying stars and stellar remnants to the scaled sizes of the Sun, Earth, distan ...
... again use a scale factor of 1 to 10 billion. Working individually of in small groups, students determine the scaled sizes of exotic objects such as red giants, white dwarfs, and black holes. They then compare the sizes of dying stars and stellar remnants to the scaled sizes of the Sun, Earth, distan ...
Final Exam - Practice questions for Unit V
... the smaller its radius when on the main sequence. ...
... the smaller its radius when on the main sequence. ...
The Milky Way - TCNJ | The College of New Jersey
... Distances from Variable Stars • Certain stars act as “standard candles” with fixed LUMINOSITY (M) • So, MEASURED BRIGHTNESS (m) lets us compute their distances. • RR Lyrae stars all have similar absolute magnitudes (around -0.5 to -1.5). Their periods are all less than one day. They can be seen in ...
... Distances from Variable Stars • Certain stars act as “standard candles” with fixed LUMINOSITY (M) • So, MEASURED BRIGHTNESS (m) lets us compute their distances. • RR Lyrae stars all have similar absolute magnitudes (around -0.5 to -1.5). Their periods are all less than one day. They can be seen in ...
Magnitude Scale
... – The smaller (or more negative) the number, the more blue (and hot) the star. ...
... – The smaller (or more negative) the number, the more blue (and hot) the star. ...
Early Star Formation: The Radial Infall Model
... know the source frequency”? Which leads one to a brief discussion of quantum mechanics. It turns out that objects, this case molecules or atoms, emit radiation of a very specific frequency when they are lowered from a high energy state to a lower energy state. The reasons for the change of states ar ...
... know the source frequency”? Which leads one to a brief discussion of quantum mechanics. It turns out that objects, this case molecules or atoms, emit radiation of a very specific frequency when they are lowered from a high energy state to a lower energy state. The reasons for the change of states ar ...
Progenitors and Hydrodynamics of Type II and lb Supernovae
... ilar to that accompanying iron core collapse in larger stars, but with some observational distinctions. First, the density gradient at the edge of the ONeMg core is very steep. Little 56 Ni will be produced. Mayle & Wilson (1988) calculate ~0.002 M 0 of 56 Ni for a model of this sort. Also the envel ...
... ilar to that accompanying iron core collapse in larger stars, but with some observational distinctions. First, the density gradient at the edge of the ONeMg core is very steep. Little 56 Ni will be produced. Mayle & Wilson (1988) calculate ~0.002 M 0 of 56 Ni for a model of this sort. Also the envel ...
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.