AST1100 Lecture Notes
... You will encounter the Hertzsprung-Russell (HR) diagram on several occations during this course. Here you will only get a short introduction and just enough information in order to be able to use it for the estimation of distances. In the lectures on stellar evolution, you will get more details. The ...
... You will encounter the Hertzsprung-Russell (HR) diagram on several occations during this course. Here you will only get a short introduction and just enough information in order to be able to use it for the estimation of distances. In the lectures on stellar evolution, you will get more details. The ...
Massive stars as thermonuclear reactors and their explosions
... of matter with mass, e.g. protons and neutrons. Because of the high entropy as the universe expanded, there was time to manufacture elements only upto helium and the major products of cosmic nucleosynthesis remained the light elements hydrogen and helium2 . Stars formed from this primordial matter. ...
... of matter with mass, e.g. protons and neutrons. Because of the high entropy as the universe expanded, there was time to manufacture elements only upto helium and the major products of cosmic nucleosynthesis remained the light elements hydrogen and helium2 . Stars formed from this primordial matter. ...
Module1: Scale of the Universe
... Ask&your&students&to&discuss&some&possible&difBiculties&of&measuring&cosmic& distances&using¶llax.&Ensure&they&mention&the&following&points:& Parallax&shifts&are&always&small.&& Parallax&shift&is&even&smaller&than&the&apparent&size&of&the&star.&In&additional,& starlight&is&refracted&by&Earth's&a ...
... Ask&your&students&to&discuss&some&possible&difBiculties&of&measuring&cosmic& distances&using¶llax.&Ensure&they&mention&the&following&points:& Parallax&shifts&are&always&small.&& Parallax&shift&is&even&smaller&than&the&apparent&size&of&the&star.&In&additional,& starlight&is&refracted&by&Earth's&a ...
ASTR 1101-001 Spring 2008 - Louisiana State University
... Masses obtained from Fig. 17-21 and Table 19-1 ...
... Masses obtained from Fig. 17-21 and Table 19-1 ...
5 Report of the Panel on Stars and Stellar Evolution
... (MHD) processes. New technology for optical and infrared (IR) spectropolarimetry and for interferometry open up the possibility of seeing magnetic fields and resolving the disks of stars. When well-sampled imaging is coupled to powerful systems for processing vast quantities of data sampled over tim ...
... (MHD) processes. New technology for optical and infrared (IR) spectropolarimetry and for interferometry open up the possibility of seeing magnetic fields and resolving the disks of stars. When well-sampled imaging is coupled to powerful systems for processing vast quantities of data sampled over tim ...
Fast Optical Transients - Harvard-Smithsonian Center for Astrophysics
... et al. 1994 only invoke a 0.2 M! hydrogen envelope). We also note that although many transients with bright cooling envelope emission are Type IIb SN, with a portion of their hydrogen envelopes remaining, Kleiser & Kasen (2014) has also modeled the Type Ic SN 2010X with the main power source being o ...
... et al. 1994 only invoke a 0.2 M! hydrogen envelope). We also note that although many transients with bright cooling envelope emission are Type IIb SN, with a portion of their hydrogen envelopes remaining, Kleiser & Kasen (2014) has also modeled the Type Ic SN 2010X with the main power source being o ...
Chapter 18 - Origin and Evolution of Stars Chapter Preview
... hunter of Greek mythology (demarcated by lines). Dangling from Orion’s three-star belt is his sword. One of the bright sword stars is the Orion Nebula a noted site of recent and ongoing star formation. FMW 399-20.2, Modified. Panel B: An expanded view showing the Orion Nebula (lower right hand corne ...
... hunter of Greek mythology (demarcated by lines). Dangling from Orion’s three-star belt is his sword. One of the bright sword stars is the Orion Nebula a noted site of recent and ongoing star formation. FMW 399-20.2, Modified. Panel B: An expanded view showing the Orion Nebula (lower right hand corne ...
Spectral modeling of nebular-phase supernovae Anders Jerkstrand Department of Astronomy
... to analyze them. The specific aims of this thesis have been to develop state-of-the-art computational models for nebular-phase SNe, and apply these models to derive properties of hydrogen-rich core-collapse SNe. We initially investigate the very late phases of the famous SN 1987A, which has mainly b ...
... to analyze them. The specific aims of this thesis have been to develop state-of-the-art computational models for nebular-phase SNe, and apply these models to derive properties of hydrogen-rich core-collapse SNe. We initially investigate the very late phases of the famous SN 1987A, which has mainly b ...
Studying explosive phenomena in astrophysics by the example of
... The formation of the first stars hundreds of millions of years after the Big-Bang marks the end of the so-called Dark Ages. Currently, we have no direct observations on how the primordial stars (Population III stars) formed, but according to modern theory of stellar evolution these stars should be v ...
... The formation of the first stars hundreds of millions of years after the Big-Bang marks the end of the so-called Dark Ages. Currently, we have no direct observations on how the primordial stars (Population III stars) formed, but according to modern theory of stellar evolution these stars should be v ...
Pair instability supernovae: Evolution, explosion, nucleosynthesis
... supernovae are exploding in the visible Universe each second, and at present there are a few of them discovered every day. The average peak luminosity of a supernova competes with that of entire galaxies. Supernovae are the main contributor of heavy elements, energy and momentum to the interstellar ...
... supernovae are exploding in the visible Universe each second, and at present there are a few of them discovered every day. The average peak luminosity of a supernova competes with that of entire galaxies. Supernovae are the main contributor of heavy elements, energy and momentum to the interstellar ...
How To Find Newborn Black Holes Kazumi Kashiyama (UCB)
... The shock has decreased significantly in strength by the time it reaches the base of the hydrogen envelope; however, this envelope is very tenuously bound in both RSG15 and RSG25. For each model we tested six choices of TOV limit (2.0 - 2.5 M⊙ , in 0.1 M⊙ increments) and evaluated the strength of th ...
... The shock has decreased significantly in strength by the time it reaches the base of the hydrogen envelope; however, this envelope is very tenuously bound in both RSG15 and RSG25. For each model we tested six choices of TOV limit (2.0 - 2.5 M⊙ , in 0.1 M⊙ increments) and evaluated the strength of th ...
AST1100 Lecture Notes
... energy is transfered outwards. Convection is a much more efficient way of energy transport than radiation. • By conduction: Heat is transfered directly outwards by particle collisions. In stars, mostly the two former mechanisms for energy transport are at play. In solar mass stars, energy is transpo ...
... energy is transfered outwards. Convection is a much more efficient way of energy transport than radiation. • By conduction: Heat is transfered directly outwards by particle collisions. In stars, mostly the two former mechanisms for energy transport are at play. In solar mass stars, energy is transpo ...
Neutron Stars - Lick Observatory
... and radii R ! 10–15 km. They consist predominantly of NEUTRONS and a few percent of PROTONS and ELECTRONS. These huge neutron-rich ‘nuclei’ are bound by gravitation and require a minimum neutron star mass of ~0.1M". Above a maximum (Chandrasekhar) mass of order 2–3M" neutron stars are unstable towar ...
... and radii R ! 10–15 km. They consist predominantly of NEUTRONS and a few percent of PROTONS and ELECTRONS. These huge neutron-rich ‘nuclei’ are bound by gravitation and require a minimum neutron star mass of ~0.1M". Above a maximum (Chandrasekhar) mass of order 2–3M" neutron stars are unstable towar ...
Chapter 2 Surveying the stars 2.1 Star magnitudes
... which is the light energy per second per unit surface area received from the star at normal incidence on a surface. The intensity of sunlight at the Earth’s surface is about 1400 W m−2. In comparison, the intensity of light from the faintest star that can be seen with the unaided eye is more than a ...
... which is the light energy per second per unit surface area received from the star at normal incidence on a surface. The intensity of sunlight at the Earth’s surface is about 1400 W m−2. In comparison, the intensity of light from the faintest star that can be seen with the unaided eye is more than a ...
neutron star - Chabot College
... • Novae occur when hydrogen fusion suddenly ignites on the surface of a white dwarf in a binary system. In contrast, hydrogen fusion is steady on the surface of a neutron star in a binary system. However, the steady hydrogen burning builds up a layer of helium beneath the surface shell of hydrogen. ...
... • Novae occur when hydrogen fusion suddenly ignites on the surface of a white dwarf in a binary system. In contrast, hydrogen fusion is steady on the surface of a neutron star in a binary system. However, the steady hydrogen burning builds up a layer of helium beneath the surface shell of hydrogen. ...
Stellar Physics
... This produces a permanent record which can be analysed in due course. It can also be exposed for many hours and hence record images of objects that may be millions of times too faint to be seen by the naked eye. Although photographic film played a crucial role in the history and development of stell ...
... This produces a permanent record which can be analysed in due course. It can also be exposed for many hours and hence record images of objects that may be millions of times too faint to be seen by the naked eye. Although photographic film played a crucial role in the history and development of stell ...
Module3: Life of a Star
... from these stars ejects material into the surroundings at very high velocities, sweeping up the surrounding interstellar gas into a shell or a giant bubble. This is known as a supernova remnant. The ejected material and the swept-up compressed gas are very hot. The shell (or bubble) shines at differ ...
... from these stars ejects material into the surroundings at very high velocities, sweeping up the surrounding interstellar gas into a shell or a giant bubble. This is known as a supernova remnant. The ejected material and the swept-up compressed gas are very hot. The shell (or bubble) shines at differ ...
Non-spherical core collapse supernovae-I. Neutrino
... supergiant progenitor is presented, that confirms our earlier type II models and extends their validity to times as late as 5.5 hours after core bounce. We also study a type Ib-like explosion, by simply removing the hydrogen envelope of the progenitor model. This allows for a first comparison of typ ...
... supergiant progenitor is presented, that confirms our earlier type II models and extends their validity to times as late as 5.5 hours after core bounce. We also study a type Ib-like explosion, by simply removing the hydrogen envelope of the progenitor model. This allows for a first comparison of typ ...
pps - TUM
... points in the rp-process because the protonbinding energy for the next nucleus is very low. The situation here is similar: once the flow has entered into a magic neutron number nucleus, capturing another neutron is inefficient because the neutron binding energy of the neighbouring (n+1) nucleus is l ...
... points in the rp-process because the protonbinding energy for the next nucleus is very low. The situation here is similar: once the flow has entered into a magic neutron number nucleus, capturing another neutron is inefficient because the neutron binding energy of the neighbouring (n+1) nucleus is l ...
Models for GRBs and diverse transients
... approximately 1051 erg has already happened and its initial blast reached the surface of the star before a weak jet, in this case 1048 erg sK1, finally arrives. The total energy in this jet, approximately 1050 erg per jet (and there is one at the other pole), is not especially small, just its power. ...
... approximately 1051 erg has already happened and its initial blast reached the surface of the star before a weak jet, in this case 1048 erg sK1, finally arrives. The total energy in this jet, approximately 1050 erg per jet (and there is one at the other pole), is not especially small, just its power. ...
Chapters 12 and 13 Review: The Life Cycle and Death of Stars
... • A star remains on the main sequence as long as it can fuse hydrogen into helium in its core. – About 90% of total lifetime is spent on main sequence – Stable energy generation during this phase. • Once the core H fuel is gone, the star evolves rapidly off the main-sequence, spending much o ...
... • A star remains on the main sequence as long as it can fuse hydrogen into helium in its core. – About 90% of total lifetime is spent on main sequence – Stable energy generation during this phase. • Once the core H fuel is gone, the star evolves rapidly off the main-sequence, spending much o ...
Document
... role of weak interactions in SN dynamics. • Tritium beta decay mass limit plus knowledge of the large mixing angles implying that all mass eigenstates are limited, meaning active neutrinos cannot be the dark matter. This is independently confirmed by the cosmology limits. Both results had important ...
... role of weak interactions in SN dynamics. • Tritium beta decay mass limit plus knowledge of the large mixing angles implying that all mass eigenstates are limited, meaning active neutrinos cannot be the dark matter. This is independently confirmed by the cosmology limits. Both results had important ...
Lecture 12: Evolution of the Galaxy
... into the ISM • Further heavy elements may be formed during the explosion in high temperature shock waves • The ejecta intially travel out at about 10,000 km/s and eventually become well mixed with the surrounding ISM • Ejecta sweep up neutral H in a snow-plough action over some 105 years before the ...
... into the ISM • Further heavy elements may be formed during the explosion in high temperature shock waves • The ejecta intially travel out at about 10,000 km/s and eventually become well mixed with the surrounding ISM • Ejecta sweep up neutral H in a snow-plough action over some 105 years before the ...
Comparison of low- and high-mass star formation
... to competitive accretion. One may plausibly identify the dense filament in the early phase and the dense region at the bottom of the global gravitational potential well in the late phase as a McKee–Tan core (McKee & Tan 2003). However, the “cores” so identified are transient objects that are not in ...
... to competitive accretion. One may plausibly identify the dense filament in the early phase and the dense region at the bottom of the global gravitational potential well in the late phase as a McKee–Tan core (McKee & Tan 2003). However, the “cores” so identified are transient objects that are not in ...
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 called a ...
... 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 called a ...
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.