Scientific Background Paper: Iron`s Place and Role
... millions of years of the evolution up to this point. The process begins when a high-energy gamma-ray strips a light nucleus from a heavy target nucleus (e.g. Sulphur-32). The light nucleus could be a proton, a neutron or an alpha particle (a Helium-4 nucleus). These light nuclei then rapidly combine ...
... millions of years of the evolution up to this point. The process begins when a high-energy gamma-ray strips a light nucleus from a heavy target nucleus (e.g. Sulphur-32). The light nucleus could be a proton, a neutron or an alpha particle (a Helium-4 nucleus). These light nuclei then rapidly combine ...
Notes 6 - University of Northern Iowa
... Since they are very small it takes them a long time to cool off. It is possible that they crystallize as they cool down, with a structure like a diamond resulting. There is observational evidence that such stars actually exist. The star BPM 37093 is a DAV white dwarf (“V”=variable) with a hydrogen a ...
... Since they are very small it takes them a long time to cool off. It is possible that they crystallize as they cool down, with a structure like a diamond resulting. There is observational evidence that such stars actually exist. The star BPM 37093 is a DAV white dwarf (“V”=variable) with a hydrogen a ...
Life as a Low Mass Red Giant
... Main sequence Turnoff: Cluster Age Verification: Clusters. Can easily check this story by looking at HR diagrams of star clusters of different ages: • As cluster ages, most massive stars run out of core Hydrogen first, moving to Red Giant stage: The point where stars are just leaving the Main Sequen ...
... Main sequence Turnoff: Cluster Age Verification: Clusters. Can easily check this story by looking at HR diagrams of star clusters of different ages: • As cluster ages, most massive stars run out of core Hydrogen first, moving to Red Giant stage: The point where stars are just leaving the Main Sequen ...
neutron star.
... — Measure velocity and distance of orbiting gas • It’s a black hole if it’s not a star and its mass exceeds the neutron star limit (~3 MSun). ...
... — Measure velocity and distance of orbiting gas • It’s a black hole if it’s not a star and its mass exceeds the neutron star limit (~3 MSun). ...
Slides from Lecture19 - Department of Physics & Astronomy
... Determining Size of MW Galaxy • We have not always known that the diameter of our Galaxy is ~ 50 kpc (as illustrated in following slide) • For example, Herschel’s map of our Galaxy (1785) based on star counts … – Thin disk not much more than 1 kpc across – Sun approximately at center of disk ...
... Determining Size of MW Galaxy • We have not always known that the diameter of our Galaxy is ~ 50 kpc (as illustrated in following slide) • For example, Herschel’s map of our Galaxy (1785) based on star counts … – Thin disk not much more than 1 kpc across – Sun approximately at center of disk ...
The coupling between the core/cusp and missing satellite problems
... We calculate the energy that baryons must inject in cold dark matter (CDM) haloes in order to remove centrally-divergent DM cusps on scales relevant to observations of dwarf spheroidal galaxies (dSphs). We estimate that the CDM haloes often associated with the Milky Way’s dSphs (Mvir /M⊙ ∼ 109−10 ) ...
... We calculate the energy that baryons must inject in cold dark matter (CDM) haloes in order to remove centrally-divergent DM cusps on scales relevant to observations of dwarf spheroidal galaxies (dSphs). We estimate that the CDM haloes often associated with the Milky Way’s dSphs (Mvir /M⊙ ∼ 109−10 ) ...
On the nature and detectability of Type Ib/c supernova progenitors
... However, rapid expansion of the helium envelope during and after the carbon-burning phase suddenly makes these stars lumi3 ...
... However, rapid expansion of the helium envelope during and after the carbon-burning phase suddenly makes these stars lumi3 ...
Facilitator`s Guide
... The process of “measuring” the stars and the distance to them is a combination of direct measurement, inference and indirect measurement. All direct measurements of stars, and the only measurements that can be made, involve the detection of the energy they emit (typically the visible light energy) t ...
... The process of “measuring” the stars and the distance to them is a combination of direct measurement, inference and indirect measurement. All direct measurements of stars, and the only measurements that can be made, involve the detection of the energy they emit (typically the visible light energy) t ...
black hole
... The core of helium ash cannot generate nuclear energy. Nevertheless, it can grow hotter—because it contracts and converts gravitational energy into thermal energy. The rising temperature heats the unprocessed hydrogen just outside the core—hydrogen that was never previously hot enough to fuse. ...
... The core of helium ash cannot generate nuclear energy. Nevertheless, it can grow hotter—because it contracts and converts gravitational energy into thermal energy. The rising temperature heats the unprocessed hydrogen just outside the core—hydrogen that was never previously hot enough to fuse. ...
copyright 2002 scientific american, inc.
... so close to the speed of light, the timescale witnessed by an external observer is vastly compressed, according to the principles of relativity. So the observer sees a burst of gamma rays that lasts only a few seconds, even if it took a day to produce. The fireball continues to expand, and eventuall ...
... so close to the speed of light, the timescale witnessed by an external observer is vastly compressed, according to the principles of relativity. So the observer sees a burst of gamma rays that lasts only a few seconds, even if it took a day to produce. The fireball continues to expand, and eventuall ...
chapter18StarDeath
... What would gas in disk do if there were no friction? A. It would orbit indefinitely. B. It would eventually fall in. C. It would blow away. ...
... What would gas in disk do if there were no friction? A. It would orbit indefinitely. B. It would eventually fall in. C. It would blow away. ...
Chapter 18 The Bizarre Stellar Graveyard What is a white dwarf
... close binary system? – The accretion disk around a neutron star gets hot enough to produce X-rays, making the system an X-ray binary – Sudden fusion events periodically occur on a the surface of an accreting neutron star, ...
... close binary system? – The accretion disk around a neutron star gets hot enough to produce X-rays, making the system an X-ray binary – Sudden fusion events periodically occur on a the surface of an accreting neutron star, ...
L17 SHELL-SHOCKED DIFFUSION MODEL FOR THE LIGHT
... the passage of the blast wave through this shell. This model differs from traditional models of supernova debris interacting with an external circumstellar medium (CSM) in that here the shell is optically thick and the escape of radiation is delayed. We show that any model attempting to account for ...
... the passage of the blast wave through this shell. This model differs from traditional models of supernova debris interacting with an external circumstellar medium (CSM) in that here the shell is optically thick and the escape of radiation is delayed. We show that any model attempting to account for ...
Copyright 1995 Scientific American, Inc.
... stars should not have existed. Astronomers believed that the repeated stellar catastrophes needed to create them would disrupt any gravitational binding between two stars. Neutron stars are the remnants of massive stars, which perish in a supernova explosion after exhausting all their nuclear fuel. ...
... stars should not have existed. Astronomers believed that the repeated stellar catastrophes needed to create them would disrupt any gravitational binding between two stars. Neutron stars are the remnants of massive stars, which perish in a supernova explosion after exhausting all their nuclear fuel. ...
Neutron Stars PowerPoint
... – Pressure & temperature are average properties • A few particles will have quite low actual values • These particles can remain separated as free particles ...
... – Pressure & temperature are average properties • A few particles will have quite low actual values • These particles can remain separated as free particles ...
Neutron Stars PowerPoint
... – Pressure & temperature are average properties • A few particles will have quite low actual values • These particles can remain separated as free particles ...
... – Pressure & temperature are average properties • A few particles will have quite low actual values • These particles can remain separated as free particles ...
The Evolution of Stars - a More Detailed Picture (Chapter 8
... Potential Energy is transformed into kinetic energy, which gets thermalised, so the temperature goes up. This phase lasts a relatively short time. When the cloud is hot enough, the gas is ionised and OPACITY sets in. When that is the case, the gas finds it harder to lose energy, and becomes hotter e ...
... Potential Energy is transformed into kinetic energy, which gets thermalised, so the temperature goes up. This phase lasts a relatively short time. When the cloud is hot enough, the gas is ionised and OPACITY sets in. When that is the case, the gas finds it harder to lose energy, and becomes hotter e ...
Chapter 12 Stellar Evolution
... • A star of more than 8 solar masses can fuse elements far beyond carbon in its core, leading to a very different fate. • Its path across the H–R diagram is essentially a straight line; it stays at just about the same luminosity as it cools off. • Eventually, the star dies in a violent explosion cal ...
... • A star of more than 8 solar masses can fuse elements far beyond carbon in its core, leading to a very different fate. • Its path across the H–R diagram is essentially a straight line; it stays at just about the same luminosity as it cools off. • Eventually, the star dies in a violent explosion cal ...
PART II: Life of a Star
... • Metal-poor stars in particular can provide constraints on: • Big Bang Nucleosynthesis (eg. 7Li in Halo stars) • The nature of Population III, the First Stars •The First Mass Function, thought to be different at Z=0 (spectrographic observations of metal-poor stars can tell us a lot about the mass d ...
... • Metal-poor stars in particular can provide constraints on: • Big Bang Nucleosynthesis (eg. 7Li in Halo stars) • The nature of Population III, the First Stars •The First Mass Function, thought to be different at Z=0 (spectrographic observations of metal-poor stars can tell us a lot about the mass d ...
Formation of a Black Hole in the Dark - CEA-Irfu
... that the black holes in these two x-ray binaries were formed through different evolutionary paths. The black hole in GRO J1655-40 has a mass of (5.4 ± 0.3) MՎ (13) and was formed through an energetic supernova explosion and fall-back on a neutron star. The black hole in Cygnus X-1 which has a mass o ...
... that the black holes in these two x-ray binaries were formed through different evolutionary paths. The black hole in GRO J1655-40 has a mass of (5.4 ± 0.3) MՎ (13) and was formed through an energetic supernova explosion and fall-back on a neutron star. The black hole in Cygnus X-1 which has a mass o ...
Chapter 8 Pre-galactic enrichment of the IGM 8.1 Summary
... The simulation was initialized at z=99 and was allowed to evolve to z=15 using the Eulerian adaptive mesh refinement code Enzo (as described in Chapter 2). The simulation was stopped at z = 15 and all halos with dark matter mass MDM ≥ 5 × 105 M! were found using the HOP halo-finding algorithm [196] ...
... The simulation was initialized at z=99 and was allowed to evolve to z=15 using the Eulerian adaptive mesh refinement code Enzo (as described in Chapter 2). The simulation was stopped at z = 15 and all halos with dark matter mass MDM ≥ 5 × 105 M! were found using the HOP halo-finding algorithm [196] ...
Practice Exam for 3 rd Astronomy Exam
... The Roman numeral in HII means that one electron has been removed from the hydrogen atom. Thus HII is hydrogen with its only electron removed creating a positive hydrogen ion. HI is regular neutral hydrogen with no electrons removed. You cannot have HIII because that would mean that 2 electrons have ...
... The Roman numeral in HII means that one electron has been removed from the hydrogen atom. Thus HII is hydrogen with its only electron removed creating a positive hydrogen ion. HI is regular neutral hydrogen with no electrons removed. You cannot have HIII because that would mean that 2 electrons have ...
Spectra of Star Clusters
... But the Universe is 1.37 x 1010 yr old! Every M dwarf that was ever created is still on the main sequence!! ...
... But the Universe is 1.37 x 1010 yr old! Every M dwarf that was ever created is still on the main sequence!! ...
Electromagnetic pulse from final gravitational stellar collapse
... off the MEMP, while in the latter case, final black hole formation at radius = ag occurs almost instantaneously later after the simulation ends. Because of the gravitational redshift, the final stellar trajectory from 2ag to ag adds little to the observable energy at infinity. Thus the MEMP calculat ...
... off the MEMP, while in the latter case, final black hole formation at radius = ag occurs almost instantaneously later after the simulation ends. Because of the gravitational redshift, the final stellar trajectory from 2ag to ag adds little to the observable energy at infinity. Thus the MEMP calculat ...
Supernova
A supernova is a stellar explosion that briefly outshines an entire galaxy, radiating as much energy as the Sun or any ordinary star is expected to emit over its entire life span, before fading from view over several weeks or months. The extremely luminous burst of radiation expels much or all of a star's material at a velocity of up to 7007300000000000000♠30,000 km/s (10% of the speed of light), driving a shock wave into the surrounding interstellar medium. This shock wave sweeps up an expanding shell of gas and dust called a supernova remnant. Supernovae are potentially strong galactic sources of gravitational waves. A great proportion of primary cosmic rays comes from supernovae.Supernovae are more energetic than novae. Nova means ""new"" in Latin, referring to what appears to be a very bright new star shining in the celestial sphere; the prefix ""super-"" distinguishes supernovae from ordinary novae, which are far less luminous. The word supernova was coined by Walter Baade and Fritz Zwicky in 1931. It is pronounced /ˌsuːpərnoʊvə/ with the plural supernovae /ˌsuːpərnoʊviː/ or supernovas (abbreviated SN, plural SNe after ""supernovae"").Supernovae can be triggered in one of two ways: by the sudden re-ignition of nuclear fusion in a degenerate star; or by the gravitational collapse of the core of a massive star. In the first case, a degenerate white dwarf may accumulate sufficient material from a companion, either through accretion or via a merger, to raise its core temperature, ignite carbon fusion, and trigger runaway nuclear fusion, completely disrupting the star. In the second case, the core of a massive star may undergo sudden gravitational collapse, releasing gravitational potential energy that can create a supernova explosion.The most recent directly observed supernova in the Milky Way was Kepler's Star of 1604 (SN 1604); remnants of two more recent supernovae have been found retrospectively. Observations in other galaxies indicate that supernovae should occur on average about three times every century in the Milky Way, and that any galactic supernova would almost certainly be observable in modern astronomical equipment. Supernovae play a significant role in enriching the interstellar medium with higher mass elements. Furthermore, the expanding shock waves from supernova explosions can trigger the formation of new stars.