Evolution of Stars
... End of the road for our Sun and similar stars. Material does not go back into the ISM. Core contracts and heats up; thermal energy ignites shell fusion. Double-shell fusion is very unstable process. Rest of star expands enormously due to extreme luminosity. Thermal pulses give outer regions escape v ...
... End of the road for our Sun and similar stars. Material does not go back into the ISM. Core contracts and heats up; thermal energy ignites shell fusion. Double-shell fusion is very unstable process. Rest of star expands enormously due to extreme luminosity. Thermal pulses give outer regions escape v ...
Lecture 9
... As the helium core grows, it compresses. Helium doesn’t fuse to heavier elements for two reasons. (1) with 2 p+ per nucleus, the electric repulsion force is higher than was the case for H-fusion. This means that helium fusion requires a higher temperature than hydrogen fusion -- 100 million K ( ...
... As the helium core grows, it compresses. Helium doesn’t fuse to heavier elements for two reasons. (1) with 2 p+ per nucleus, the electric repulsion force is higher than was the case for H-fusion. This means that helium fusion requires a higher temperature than hydrogen fusion -- 100 million K ( ...
Chapter 12 Pre-supernova evolution of massive stars
... temperature reached in these stars is smaller than the temperature required for carbon fusion. During the latest stages of evolution on the AGB these stars undergo strong mass loss which removes the remaining envelope, so that their final remnants are C-O white dwarfs. The evolution of massive stars ...
... temperature reached in these stars is smaller than the temperature required for carbon fusion. During the latest stages of evolution on the AGB these stars undergo strong mass loss which removes the remaining envelope, so that their final remnants are C-O white dwarfs. The evolution of massive stars ...
Luminosity Classes
... In general the less dense a star is the more luminous it will be (because it has more surface area). Luminosity and the thickness of the absorption lines are combined to group stars into Lumniosity Classes. Luminosity Classes are combined with spectral class to describe Stars. The Sun is Class V so ...
... In general the less dense a star is the more luminous it will be (because it has more surface area). Luminosity and the thickness of the absorption lines are combined to group stars into Lumniosity Classes. Luminosity Classes are combined with spectral class to describe Stars. The Sun is Class V so ...
Opakování z minulého cvičení
... • A small star does not have to burn its hydrogen very quickly in order to generate enough heat to hold it up against the inward tug of gravity, so it sits at the cool end of the main sequence, • a massive star has to burn a lot of fuel every second to prevent itself from collapsing under its own we ...
... • A small star does not have to burn its hydrogen very quickly in order to generate enough heat to hold it up against the inward tug of gravity, so it sits at the cool end of the main sequence, • a massive star has to burn a lot of fuel every second to prevent itself from collapsing under its own we ...
Core Collapse Supernovae and Neutron Star Kicks, a Primer David
... the core will undergo a supernova and as it collapses the asymmetric density will cause the emission from the supernova to be asymmetric and kick the resultant neutron star. This mechanism doesn't require an extremely strong magnetic field, or necessarily imply that the kick direction and the neutro ...
... the core will undergo a supernova and as it collapses the asymmetric density will cause the emission from the supernova to be asymmetric and kick the resultant neutron star. This mechanism doesn't require an extremely strong magnetic field, or necessarily imply that the kick direction and the neutro ...
Stellar Evolution 1
... What happens as Hydrogen is fused into Helium in core of a star? 6. As a result of the increase in the rate of nuclear energy generation, what happens to the Luminosity a) It increases b) It remains the same (until the pressure outside the core builds up enough to make the surrounding envelope expa ...
... What happens as Hydrogen is fused into Helium in core of a star? 6. As a result of the increase in the rate of nuclear energy generation, what happens to the Luminosity a) It increases b) It remains the same (until the pressure outside the core builds up enough to make the surrounding envelope expa ...
Luminosity Classes
... In general the less dense a star is the more luminous it will be (because it has more surface area). Luminosity and the thickness of the absorption lines are combined to group stars into Lumniosity Classes. Luminosity Classes are combined with spectral class to describe Stars. The Sun is Class V so ...
... In general the less dense a star is the more luminous it will be (because it has more surface area). Luminosity and the thickness of the absorption lines are combined to group stars into Lumniosity Classes. Luminosity Classes are combined with spectral class to describe Stars. The Sun is Class V so ...
Properties of long gamma-ray bursts from massive compact binaries
... We use the binary population of Church et al. [7], within which we searched for double blackhole binaries that satisfy the criterion of Levan et al. [6]. In summary, this requires that the binary be tight enough that, assuming tidal locking, the core is spun up sufficiently that its outer parts form ...
... We use the binary population of Church et al. [7], within which we searched for double blackhole binaries that satisfy the criterion of Levan et al. [6]. In summary, this requires that the binary be tight enough that, assuming tidal locking, the core is spun up sufficiently that its outer parts form ...
The Next 2-3 Weeks
... Core collapse supernovae • Massive stars (M > 8 or10 Msun) • Wide range in M wide range in L • Not useful as “standard candles” ...
... Core collapse supernovae • Massive stars (M > 8 or10 Msun) • Wide range in M wide range in L • Not useful as “standard candles” ...
Recipes for ULX formation: necessary ingredients and garnishments
... Myr (Portegies Zwart & McMillan 2002). However, we have argued that there is no longer a compelling need to invoke intermediate-mass BHs in ULXs, and that the upper mass limit is likely to be somewhere between 50 and 200M . Correspondingly, if dynamical collapse and merger processes are still neede ...
... Myr (Portegies Zwart & McMillan 2002). However, we have argued that there is no longer a compelling need to invoke intermediate-mass BHs in ULXs, and that the upper mass limit is likely to be somewhere between 50 and 200M . Correspondingly, if dynamical collapse and merger processes are still neede ...
When Stars Attack! In Search of Killer Supernovae
... In our Milky Way galaxy: Ø About 1 SN/century Ø Most far away: spectacular but ...
... In our Milky Way galaxy: Ø About 1 SN/century Ø Most far away: spectacular but ...
Cosmic Connection to the elements
... As the Universe expanded, the temperature fell. At this point the protons and electrons no longer had enough energy to collide to form neutrons. Thus, the number of protons and neutrons in the Universe stabilized, with protons outnumbering neutrons by 7:1. At about 100 seconds after the Big Bang, th ...
... As the Universe expanded, the temperature fell. At this point the protons and electrons no longer had enough energy to collide to form neutrons. Thus, the number of protons and neutrons in the Universe stabilized, with protons outnumbering neutrons by 7:1. At about 100 seconds after the Big Bang, th ...
Life Stages of High
... • After core helium fusion stops, He fuses into carbon in a shell around the carbon core, and H fuses to He in a shell around the helium layer • This double-shell burning stage never reaches equilibrium—fusion rate periodically spikes upward in a series of thermal pulses ...
... • After core helium fusion stops, He fuses into carbon in a shell around the carbon core, and H fuses to He in a shell around the helium layer • This double-shell burning stage never reaches equilibrium—fusion rate periodically spikes upward in a series of thermal pulses ...
The Evryscope: the first full-sky gigapixel-scale telescope Nicholas Law
... Asteroids around white dwarfs Confirmation of long-period TESS single-transit detections ...
... Asteroids around white dwarfs Confirmation of long-period TESS single-transit detections ...
Where Do Chemical Elements Come From?
... elements in this mass range can be produced from isotopes of the aforementioned elements. These types of processes take place in stars that are relatively light—like our sun. Fusion produces heavier elements—from oxygen to iron—in stars that are more massive. The fusion processes for most nuclei are ...
... elements in this mass range can be produced from isotopes of the aforementioned elements. These types of processes take place in stars that are relatively light—like our sun. Fusion produces heavier elements—from oxygen to iron—in stars that are more massive. The fusion processes for most nuclei are ...
Stellar Lives (continued). Galaxies.
... silicon-burning core and it becomes a red supergiant. Iron cannot be ignited. Iron has the lowest mass per nuclear particle. ...
... silicon-burning core and it becomes a red supergiant. Iron cannot be ignited. Iron has the lowest mass per nuclear particle. ...
ph507lecnote06
... Sun. The diagonal lines correspond to constant stellar radius, so that stellar size can be represented on the same diagram as luminosity and temperature. The first H-R diagrams considered stars in the solar neighbourhood and plotted absolute visual magnitude, M, versus spectral type, which is equiva ...
... Sun. The diagonal lines correspond to constant stellar radius, so that stellar size can be represented on the same diagram as luminosity and temperature. The first H-R diagrams considered stars in the solar neighbourhood and plotted absolute visual magnitude, M, versus spectral type, which is equiva ...
The Deaths of Very Massive Stars
... SN Ibc. The remnant would probably be a neutron star. It is unclear if such events have been observed, though Cas A might be a candidate. Even if the core of the star collapses to a black hole, its death is not necessarily nucleosynthetically barren or unobservable. The black hole could result from ...
... SN Ibc. The remnant would probably be a neutron star. It is unclear if such events have been observed, though Cas A might be a candidate. Even if the core of the star collapses to a black hole, its death is not necessarily nucleosynthetically barren or unobservable. The black hole could result from ...
Sample Stellar Evolution TEST QUESTIONS
... 10. Hydrostatic equilibrium refers to the balance between weight and pressure. 11. The Orion region contains young main sequence stars and an emission nebula. 12. The thermal motions of the atoms in a gas cloud can make it collapse to form a protostar. 13. The pressure of a gas generally depends on ...
... 10. Hydrostatic equilibrium refers to the balance between weight and pressure. 11. The Orion region contains young main sequence stars and an emission nebula. 12. The thermal motions of the atoms in a gas cloud can make it collapse to form a protostar. 13. The pressure of a gas generally depends on ...
Measuring Stars
... Supernovas are classified into various classes, type I, type II etc., according to features of their spectrums. One particular type called type Ia, has interesting and important properties. ...
... Supernovas are classified into various classes, type I, type II etc., according to features of their spectrums. One particular type called type Ia, has interesting and important properties. ...
Neutrinos and Supernovae
... are infrequent events. But there is one exception They occur on average to the neutrino’s demure only once every 50 years role. It occurs in the heart of or so within a given massive stars, deep within galaxy. The inhabitants of the stellar core. When a masthe northern hemisphere sive star dies, it ...
... are infrequent events. But there is one exception They occur on average to the neutrino’s demure only once every 50 years role. It occurs in the heart of or so within a given massive stars, deep within galaxy. The inhabitants of the stellar core. When a masthe northern hemisphere sive star dies, it ...
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.