CHAPTER 12—STELLAR EVOLUTION
... 1. The main sequence has a limit at the lower end because a. low mass stars form from the interstellar medium very rarely. b. hydrogen fusion combined 4 hydrogen nuclei to form 1 helium nucleus. c. pressure does not depend on temperature in degenerate matter. d. the lower limit represents when the r ...
... 1. The main sequence has a limit at the lower end because a. low mass stars form from the interstellar medium very rarely. b. hydrogen fusion combined 4 hydrogen nuclei to form 1 helium nucleus. c. pressure does not depend on temperature in degenerate matter. d. the lower limit represents when the r ...
秋 夕(七言絕句) 作者:杜牧 銀燭秋光冷畫屏,輕羅小扇撲流螢。 天階夜色
... Virgo is known as a spring constellation because, although you can see some or all of its stars on most nights of the year, the stars put on their best display in the evening sky during spring. Although blue-white Spica is Virgo's only bright star, it is the 16th-brightest star in the night sky. It ...
... Virgo is known as a spring constellation because, although you can see some or all of its stars on most nights of the year, the stars put on their best display in the evening sky during spring. Although blue-white Spica is Virgo's only bright star, it is the 16th-brightest star in the night sky. It ...
The Hydrogen Ionization Front-Photosphere
... Temperature at which Hydrogen ionizes is somewhat independent of density for low densities. Thus, when the HIF-photosphere are engaged, temperature of stellar photosphere is somewhat independent of global stellar properties, such as period, at low densities. This can lead to changes in the periodcol ...
... Temperature at which Hydrogen ionizes is somewhat independent of density for low densities. Thus, when the HIF-photosphere are engaged, temperature of stellar photosphere is somewhat independent of global stellar properties, such as period, at low densities. This can lead to changes in the periodcol ...
Lecture 16, PPT version
... • WD with mass = 1 Msun is about the size of the earth, weight of 1 teaspoon of WD material = about the weight of a small truck • If all alone in space, WD simply cool off (no internal source of energy) and eventually become black ...
... • WD with mass = 1 Msun is about the size of the earth, weight of 1 teaspoon of WD material = about the weight of a small truck • If all alone in space, WD simply cool off (no internal source of energy) and eventually become black ...
Document
... This is a transcendental equation in Pe that has to be solved iteratively. F(T) are constants for such an iteration. Pe and Pg are functions of t0. This equation is solved at each depth using the first guess of Pg(t0). ...
... This is a transcendental equation in Pe that has to be solved iteratively. F(T) are constants for such an iteration. Pe and Pg are functions of t0. This equation is solved at each depth using the first guess of Pg(t0). ...
Lecture 4 – Protoplanetary disk structure o Protoplanetary disk
... In z-direction, temperature gradients are very large (dT/dz>>0), due to the large temperature difference between the interior and the edge of the disk and the very thin disk in the vertical direction. This drives convection. ...
... In z-direction, temperature gradients are very large (dT/dz>>0), due to the large temperature difference between the interior and the edge of the disk and the very thin disk in the vertical direction. This drives convection. ...
Galaxies and Stars
... 66. Base your answer to the following question on the diagram below, which shows an inferred sequence in which our solar system formed from a giant interstellar cloud of gas and debris. Stage A shows the collapse of the gas cloud, stage B shows its flattening, and stage C shows the sequence that le ...
... 66. Base your answer to the following question on the diagram below, which shows an inferred sequence in which our solar system formed from a giant interstellar cloud of gas and debris. Stage A shows the collapse of the gas cloud, stage B shows its flattening, and stage C shows the sequence that le ...
Spectroscopy – Lecture 1
... Assumption: Ignore radiation from the rest of the universe (other stars, galaxies, etc.) This is what you need to compute a spectrum. For the sun which is resolved, intensity measurements can be made as a function of q. For stars we must integrate In over the disk since we observe the flux. ...
... Assumption: Ignore radiation from the rest of the universe (other stars, galaxies, etc.) This is what you need to compute a spectrum. For the sun which is resolved, intensity measurements can be made as a function of q. For stars we must integrate In over the disk since we observe the flux. ...
Slide 1
... study of the period evolution for both types of stars shows that most of the SRs and nearly half of the O-rich and C-rich Miras studied; show an increasing trend in their behaviour: the period is rising. So if the process responsible for this phenomenon is a thermal pulse, we can say that the stars ...
... study of the period evolution for both types of stars shows that most of the SRs and nearly half of the O-rich and C-rich Miras studied; show an increasing trend in their behaviour: the period is rising. So if the process responsible for this phenomenon is a thermal pulse, we can say that the stars ...
Lecture5
... (iiib) Radiation: energy carried by photons (`random walk’ – takes long time from interior to surface). (iiic) Convection: energy carried by particles, by gas motion (e.g. boiling watter). ...
... (iiib) Radiation: energy carried by photons (`random walk’ – takes long time from interior to surface). (iiic) Convection: energy carried by particles, by gas motion (e.g. boiling watter). ...
The physics of high-mass star formation
... detailed observational study of environment: structure (size, mass of cores) and kinematics (rotating disks, infall) on scales < 0.1 pc Monolithic collapse: disks (+jets) necessary for accretion onto OB star cluster natural outcome of s.f. process Competitive accretion (+merging): disks natural outc ...
... detailed observational study of environment: structure (size, mass of cores) and kinematics (rotating disks, infall) on scales < 0.1 pc Monolithic collapse: disks (+jets) necessary for accretion onto OB star cluster natural outcome of s.f. process Competitive accretion (+merging): disks natural outc ...
MAIN SEQUENCE STARS, Red Giants and White Dwarfs
... grown, causing the core radius to rise, thus, yielding a decline in Tc to just about 108 K. o Now He burns smoothly in the core -- producing the He BURNING MAIN SEQUENCE -- which is visible on an H-R diagram as the HORIZONTAL BRANCH (lower L but higher Ts than during the He flash). o Stars are again ...
... grown, causing the core radius to rise, thus, yielding a decline in Tc to just about 108 K. o Now He burns smoothly in the core -- producing the He BURNING MAIN SEQUENCE -- which is visible on an H-R diagram as the HORIZONTAL BRANCH (lower L but higher Ts than during the He flash). o Stars are again ...
Star Formation in the Galactic Center
... GC in a massive cluster that then spirals in. This would avoid the need for excessive gas density in order to form stars. Cluster would orbit through background stars, decay through friction, and settle in center containing ~ only He I stars. ...
... GC in a massive cluster that then spirals in. This would avoid the need for excessive gas density in order to form stars. Cluster would orbit through background stars, decay through friction, and settle in center containing ~ only He I stars. ...
Stellar populations and dynamics in the Milky Way galaxy
... gravitational instability, quantified by the Jeans mass. The Jeans mass is that minimum mass at which gravity overwhelms pressure so that density perturbations of mass M MJ ~ 108 T43/2 n1/2ML are unstable and collapse upon themselves, where the numerical factor is for temperature T in units of 10 ...
... gravitational instability, quantified by the Jeans mass. The Jeans mass is that minimum mass at which gravity overwhelms pressure so that density perturbations of mass M MJ ~ 108 T43/2 n1/2ML are unstable and collapse upon themselves, where the numerical factor is for temperature T in units of 10 ...
Chapter 8 Formation of Stars
... • Therefore, a solar-mass protostar collapses from about 25 times the radius of the Solar System to about half the radius of the Earth’s orbit in near free-fall on a timescale of about 7,000 years. • The collapse then slows because 1. All the hydrogen has been dissociated and ionized, 2. the photon ...
... • Therefore, a solar-mass protostar collapses from about 25 times the radius of the Solar System to about half the radius of the Earth’s orbit in near free-fall on a timescale of about 7,000 years. • The collapse then slows because 1. All the hydrogen has been dissociated and ionized, 2. the photon ...
Review (PPT) - Uplift Summit Intl
... ▪ For the star much bigger than the Sun when in the red giant phase, the core is so large that the resulting high temperature causes the fusion of nuclei to create elements heavier than carbon. ▪ The giant phase ends with the star having layers of elements with proton numbers that decrease from the ...
... ▪ For the star much bigger than the Sun when in the red giant phase, the core is so large that the resulting high temperature causes the fusion of nuclei to create elements heavier than carbon. ▪ The giant phase ends with the star having layers of elements with proton numbers that decrease from the ...
Chapter 7 Formation of Stars
... • Therefore, a solar-mass protostar collapses from about 25 times the radius of the Solar System to about half the radius of the Earth’s orbit in near free-fall on a timescale of about 7,000 years. • The collapse then slows because 1. All the hydrogen has been dissociated and ionized, 2. the photon ...
... • Therefore, a solar-mass protostar collapses from about 25 times the radius of the Solar System to about half the radius of the Earth’s orbit in near free-fall on a timescale of about 7,000 years. • The collapse then slows because 1. All the hydrogen has been dissociated and ionized, 2. the photon ...
Sizes of Stars - The University of Texas at Dallas
... is the source of all of the Sun’s energy. Deep inside our star is its core. Fusion can only happen in the hot dense core of the Sun. A star will stay on the main sequence until there is no more hydrogen in the star’s core that can be converted to helium. ...
... is the source of all of the Sun’s energy. Deep inside our star is its core. Fusion can only happen in the hot dense core of the Sun. A star will stay on the main sequence until there is no more hydrogen in the star’s core that can be converted to helium. ...
26.3 Life Cycles of Stars
... hydrogen, gravity gains the upper hand over pressure, and the core starts to shrink. • The core temperature rises enough to cause the hydrogen in a shell outside the core to begin fusion. • The energy flowing outward increases, causing the outer regions of the star to expand. The expanding atmospher ...
... hydrogen, gravity gains the upper hand over pressure, and the core starts to shrink. • The core temperature rises enough to cause the hydrogen in a shell outside the core to begin fusion. • The energy flowing outward increases, causing the outer regions of the star to expand. The expanding atmospher ...
HCKim_NR
... modified of the equation of state due to geodesic deviation. The curvature must be not too small and not too large. Since the curvature does not diverge, the characteristic scale must decrease! Balance between the gravity and the Fermi liquid the ratio of their correlation scales must be a good ...
... modified of the equation of state due to geodesic deviation. The curvature must be not too small and not too large. Since the curvature does not diverge, the characteristic scale must decrease! Balance between the gravity and the Fermi liquid the ratio of their correlation scales must be a good ...
Document
... What causes density waves? Smaller perturbations can be induced in galactic disks via interactions with other systems These grow to become pronounced waves. Seen in all kinds of disks, including protostellar disks! ...
... What causes density waves? Smaller perturbations can be induced in galactic disks via interactions with other systems These grow to become pronounced waves. Seen in all kinds of disks, including protostellar disks! ...
Lecture 13 Main Sequence and Low Mass Evolution
... • The higher the mass, the shorter its life. • Examples: Sun: ~ 10 Billion Years 30 Msun O‐star: ~ 2 Million years 0.1 Msun M‐star: ~ 3 Trillion years ...
... • The higher the mass, the shorter its life. • Examples: Sun: ~ 10 Billion Years 30 Msun O‐star: ~ 2 Million years 0.1 Msun M‐star: ~ 3 Trillion years ...
Testing - Elon University
... Why do orbits of bulge stars bob up and down? A. They’re stuck to interstellar medium B. Gravity of disk stars pulls toward disk C. Halo stars knock them back into disk ...
... Why do orbits of bulge stars bob up and down? A. They’re stuck to interstellar medium B. Gravity of disk stars pulls toward disk C. Halo stars knock them back into disk ...