Lec10_ch12_deathofstars
... What do you think? • Will the Sun end its existence? If so, how? – The Sun will shed its outer layers as a planetary nebula in about 7 billions years. Its remnant white dwarf, with fusion ceased, will dim over the next several billion years ...
... What do you think? • Will the Sun end its existence? If so, how? – The Sun will shed its outer layers as a planetary nebula in about 7 billions years. Its remnant white dwarf, with fusion ceased, will dim over the next several billion years ...
Stellar Evolution
... 2. As a large portion of the GMC collapses, many internal eddies and turbulent motions can exist within the cloud. As a result, when fragmentation to stellar-mass sizes occur, each little cloudlet has a rotation associated with it that was induced from one of these eddies as shown in Figure II-5. 3. ...
... 2. As a large portion of the GMC collapses, many internal eddies and turbulent motions can exist within the cloud. As a result, when fragmentation to stellar-mass sizes occur, each little cloudlet has a rotation associated with it that was induced from one of these eddies as shown in Figure II-5. 3. ...
First Light Sources at the End of the Dark Ages: Direct
... begun. Thus, near-infrared observations of these dwarfs could reveal strong Lyman ! and He II emission detectable by large ground-based telescopes, and possibly a rest-frame ultraviolet continuum observable from the ground and/or with the JWST. By 2016, the JWST and/or ground-based surveys will reg ...
... begun. Thus, near-infrared observations of these dwarfs could reveal strong Lyman ! and He II emission detectable by large ground-based telescopes, and possibly a rest-frame ultraviolet continuum observable from the ground and/or with the JWST. By 2016, the JWST and/or ground-based surveys will reg ...
Lecture 8: The Stars - Department of Physics and Astronomy
... In 1925 she was the first person to earn a Ph.D. in astronomy from Harvard. Her thesis was later called by Otto Struve the “Undoubted the most brilliant Ph.D. thesis ever written in astronomy” In 1956 she became the first female tenured professor at Harvard, and later the first female chair. ...
... In 1925 she was the first person to earn a Ph.D. in astronomy from Harvard. Her thesis was later called by Otto Struve the “Undoubted the most brilliant Ph.D. thesis ever written in astronomy” In 1956 she became the first female tenured professor at Harvard, and later the first female chair. ...
gravitational collapse to black holes
... However, whereas the TOV equations are a system of ODEs, rotating models result in a system of PDEs and need to be solved for using sophisticated numerical techniques ...
... However, whereas the TOV equations are a system of ODEs, rotating models result in a system of PDEs and need to be solved for using sophisticated numerical techniques ...
PPS
... • 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 ...
Ch. 18
... companion, which swirls toward the surface in an accretion disk. If enough hydrogen rains down on the white dwarf, the surface hydrogen layer will become so hot that it will ignite with nuclear fusion, essentially making a thermonuclear flash in which the star shines as brightly as 100,000 Suns for ...
... companion, which swirls toward the surface in an accretion disk. If enough hydrogen rains down on the white dwarf, the surface hydrogen layer will become so hot that it will ignite with nuclear fusion, essentially making a thermonuclear flash in which the star shines as brightly as 100,000 Suns for ...
The Physics of Massive Star Formation
... Combining fm due to captures and BH accretion shows for 0.5 M stars in clumps with Entire clumps have M ~ 1000 M, vir ≈ 1 no competitive accretion If clumps undergo global collapse, stagnation points form with low mass, velocities where stars stay after accreting cores (Bonnell & Bate 2006), (a ...
... Combining fm due to captures and BH accretion shows for 0.5 M stars in clumps with Entire clumps have M ~ 1000 M, vir ≈ 1 no competitive accretion If clumps undergo global collapse, stagnation points form with low mass, velocities where stars stay after accreting cores (Bonnell & Bate 2006), (a ...
death_high_mass
... Age of the universe using WD cooling • To date hundreds of thousands of White Dwarfs have been observed. • There is a temperature cut-off beyond which no white dwarfs are found. • This is because there hasn’t been enough time since the start of the universe for WD to cool any further. • The age of ...
... Age of the universe using WD cooling • To date hundreds of thousands of White Dwarfs have been observed. • There is a temperature cut-off beyond which no white dwarfs are found. • This is because there hasn’t been enough time since the start of the universe for WD to cool any further. • The age of ...
Astronomy 112: The Physics of Stars Class 16 Notes: Post
... unchanged, but moves the star to higher effective temperature. The motion is roughly horizontal in the HR diagram, so this is known as the horizontal branch – it is shown by points 7-9 . The duration of this phase is roughly 108 yr, set by the amount of energy that is produced by a combination of He ...
... unchanged, but moves the star to higher effective temperature. The motion is roughly horizontal in the HR diagram, so this is known as the horizontal branch – it is shown by points 7-9 . The duration of this phase is roughly 108 yr, set by the amount of energy that is produced by a combination of He ...
What keeps stars shining? What holds them up? Lecture 14. The
... This already illustrates the basic principle: The sun does not collapse under its own gravity because it is hot enough inside that the pressure balances gravity. But how hot is it? • Temperature Balance ("thermal equilibrium"). At every depth, the loss of heat due to cooling is exactly balanced by h ...
... This already illustrates the basic principle: The sun does not collapse under its own gravity because it is hot enough inside that the pressure balances gravity. But how hot is it? • Temperature Balance ("thermal equilibrium"). At every depth, the loss of heat due to cooling is exactly balanced by h ...
Dynamics of Stars and Black Holes in Dense Stellar Systems:
... Or, to say it in a different way (more physical?) ⇒ POTENTIAL WELL BECOMES PERMANENTLY SHALLOWER ⇒ AND SYSTEM EXPANDS (*) (*) IF the system expands, it becomes LESS DENSE ⇒ lower density implies LESS two-body encounters ⇒ stars exchange less energy and become dynamically cooler ⇒ gravothermal CATAST ...
... Or, to say it in a different way (more physical?) ⇒ POTENTIAL WELL BECOMES PERMANENTLY SHALLOWER ⇒ AND SYSTEM EXPANDS (*) (*) IF the system expands, it becomes LESS DENSE ⇒ lower density implies LESS two-body encounters ⇒ stars exchange less energy and become dynamically cooler ⇒ gravothermal CATAST ...
Document
... mass of the Sun, gravity becomes strong enough to combine electrons and protons into neutrons. During this brief period, heavier elements such as gold and uranium are created, as atomic nuclei are smashed together. The core of the star collapses and the result is a spectacular explosion called a ...
... mass of the Sun, gravity becomes strong enough to combine electrons and protons into neutrons. During this brief period, heavier elements such as gold and uranium are created, as atomic nuclei are smashed together. The core of the star collapses and the result is a spectacular explosion called a ...
SALT: a Spectral Adaptive Light curve Template for Type Ia
... 122 SNe Ia for which B- and V -band light curves are available in the literature, including data from Hamuy et al. [6], Riess et al. [20] and Jha [7] for a total of 94 objects, and 28 additional supernovae collected from various sources. Objects were then selected based on two main criteria. First, ...
... 122 SNe Ia for which B- and V -band light curves are available in the literature, including data from Hamuy et al. [6], Riess et al. [20] and Jha [7] for a total of 94 objects, and 28 additional supernovae collected from various sources. Objects were then selected based on two main criteria. First, ...
S E D
... ionization, and therefore we can assume this almost in the whole star except the surface. Another assumption we take the equation of state is that the gas is spherical and homogenous and can be assumed to be under high density. Fully ionized ideal gas; In the core, and means that T and the ionizatio ...
... ionization, and therefore we can assume this almost in the whole star except the surface. Another assumption we take the equation of state is that the gas is spherical and homogenous and can be assumed to be under high density. Fully ionized ideal gas; In the core, and means that T and the ionizatio ...
Stellar Evolution – Cosmic Cycles of Formation and Destruction
... starts evolving into a protostar, it only has about 1% of its final mass; however the envelope of the star continues to grow as infalling material continues to accrete. After a few million years, the temperature at the center of the core is hot enough for hydrogen fusion to begin, and a strong stell ...
... starts evolving into a protostar, it only has about 1% of its final mass; however the envelope of the star continues to grow as infalling material continues to accrete. After a few million years, the temperature at the center of the core is hot enough for hydrogen fusion to begin, and a strong stell ...
Contraction of a Magnetized Rotating Cloud
... Absolute value L and timescale are obtained after M is given. L M t M 1 ...
... Absolute value L and timescale are obtained after M is given. L M t M 1 ...
white dwarfs, neutron stars, black hole
... our Sun. After the outer layers of the star have swollen into a red supergiant (i.e., a very big red giant), the core begins to yield to gravity and starts to shrink. As it shrinks, it grows hotter and denser, and a new series of nuclear reactions begin to occur, temporarily halting the collapse of ...
... our Sun. After the outer layers of the star have swollen into a red supergiant (i.e., a very big red giant), the core begins to yield to gravity and starts to shrink. As it shrinks, it grows hotter and denser, and a new series of nuclear reactions begin to occur, temporarily halting the collapse of ...
Chapter 16 Lives of the Stars (Low Mass)
... Post Main Sequence life for low and intermediate mass stars • Low mass star (M < 0.2 ...
... Post Main Sequence life for low and intermediate mass stars • Low mass star (M < 0.2 ...
Stellar-mass Black Hole Formation
... Masses greater than the maximum NS mass: 1.5-2.5 Msun (from detailed EOS calculations); 3.2 Msun (upper limit from causality; Lattimer & Prakash ) ~109 SMBHs in the Galaxy, from stellar popn modeling (Brown & Bethe 1994) 20 confirmed black holes in X-ray binaries, with secure masses (as of 2006) mas ...
... Masses greater than the maximum NS mass: 1.5-2.5 Msun (from detailed EOS calculations); 3.2 Msun (upper limit from causality; Lattimer & Prakash ) ~109 SMBHs in the Galaxy, from stellar popn modeling (Brown & Bethe 1994) 20 confirmed black holes in X-ray binaries, with secure masses (as of 2006) mas ...
Low mass stars
... the 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 eq ...
... the 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 eq ...
Lokal fulltext - Chalmers Publication Library
... up in the HR diagram towards larger luminosities. This will happen sooner the more massive the star is: the Sun has a main sequence lifetime of about 10 billion years, compared with only ∼30 million years for a 10 M star. There are several tracks a star may follow in the HR diagram, depending on it ...
... up in the HR diagram towards larger luminosities. This will happen sooner the more massive the star is: the Sun has a main sequence lifetime of about 10 billion years, compared with only ∼30 million years for a 10 M star. There are several tracks a star may follow in the HR diagram, depending on it ...
Recipe for a Star
... supernova. The explosion is so powerful that it can briefly outshine an entire galaxy. It is the most violent and spectacular explosion in the universe. While the core explosion occurs in about one second, the massive-star supernova may continue to shine for weeks or months. Massive-star supernovae ...
... supernova. The explosion is so powerful that it can briefly outshine an entire galaxy. It is the most violent and spectacular explosion in the universe. While the core explosion occurs in about one second, the massive-star supernova may continue to shine for weeks or months. Massive-star supernovae ...
Learning Objectives
... dwarf, increasing its mass until it begins to collapse under its own weight. As the white dwarf collapses, it heats up, until it reaches 6 × 108 K, the temperature at which carbon fusion occurs. Since white dwarfs are primarily made of carbon, the entire star ignites and explodes, resulting in what ...
... dwarf, increasing its mass until it begins to collapse under its own weight. As the white dwarf collapses, it heats up, until it reaches 6 × 108 K, the temperature at which carbon fusion occurs. Since white dwarfs are primarily made of carbon, the entire star ignites and explodes, resulting in what ...
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.