Homework Due
... Sun releases energy by fusing four hydrogen nuclei into one helium nucleus. Starting point is 4 protons. End point is 2 p + 2 n (a helium nucleus) + energy There are several steps required to make this happen. © 2007 Pearson Education Inc., publishing as Pearson Addison-Wesley ...
... Sun releases energy by fusing four hydrogen nuclei into one helium nucleus. Starting point is 4 protons. End point is 2 p + 2 n (a helium nucleus) + energy There are several steps required to make this happen. © 2007 Pearson Education Inc., publishing as Pearson Addison-Wesley ...
A Very Dense Low-Mass Molecular Condensation in Taurus
... H 1 3 CO + J — 4-3 emission toward any starless condensations. The intensity of these H 1 3 CO + lines appears to be a good indicator of the molecular density, since the line is excited only at a density of > 10 5 - 6 c m - 3 . The intensity of the H 1 3 CO + J = 3-2 line is in fact found to be well ...
... H 1 3 CO + J — 4-3 emission toward any starless condensations. The intensity of these H 1 3 CO + lines appears to be a good indicator of the molecular density, since the line is excited only at a density of > 10 5 - 6 c m - 3 . The intensity of the H 1 3 CO + J = 3-2 line is in fact found to be well ...
The Celestial Origin of Atoms
... Aims and aspirations of nuclear astrophysics The aim of nuclear astrophysics is threefold. Firstly, it seeks to determine the mechanisms whereby the various nuclear species occurring in nature are built up, from deuterium with its two nucleons to uranium with 238 nucleons. Secondly, it seeks to iden ...
... Aims and aspirations of nuclear astrophysics The aim of nuclear astrophysics is threefold. Firstly, it seeks to determine the mechanisms whereby the various nuclear species occurring in nature are built up, from deuterium with its two nucleons to uranium with 238 nucleons. Secondly, it seeks to iden ...
The ages of pre-main-sequence stars
... often used to determine their mass and age by comparison with pre-main-sequence evolution tracks. On the assumption that the stellar models are accurate, we demonstrate that, if the metallicity is known, the mass obtained is a good estimate. However, the age determination can be very misleading, bec ...
... often used to determine their mass and age by comparison with pre-main-sequence evolution tracks. On the assumption that the stellar models are accurate, we demonstrate that, if the metallicity is known, the mass obtained is a good estimate. However, the age determination can be very misleading, bec ...
CO OBSERVATIONS OF SPIRAL STRUCTURE AND THE LIFETIME
... event would therefore need to supply a momentum of k x 1 0 MQ k m - s or it must ionize k x 1 0 MQ at an average density of 1 0 H nuclei! per cc. Since these requirements far exceed the capabilities of supernova or common 0-stars, the process of removing Hp from clouds is more likely in the form of ...
... event would therefore need to supply a momentum of k x 1 0 MQ k m - s or it must ionize k x 1 0 MQ at an average density of 1 0 H nuclei! per cc. Since these requirements far exceed the capabilities of supernova or common 0-stars, the process of removing Hp from clouds is more likely in the form of ...
Neutron Stars
... with the BC (38). For n < 5 the solution decreases monotonically and has a zero at finite value ξ = ξ1 i.e. θ(ξ1 ) = 0 which corresponds to the surface of the star, where p = ρ = 0. Thus we get: ...
... with the BC (38). For n < 5 the solution decreases monotonically and has a zero at finite value ξ = ξ1 i.e. θ(ξ1 ) = 0 which corresponds to the surface of the star, where p = ρ = 0. Thus we get: ...
Star 1 A star is a massive, luminous ball of plasma held together by
... For at least a portion of its life, a star shines due to thermonuclear fusion of hydrogen in its core releasing energy that traverses the star's interior and then radiates into outer space. Almost all naturally occurring elements heavier than helium were created by stars, either via stellar nucleosy ...
... For at least a portion of its life, a star shines due to thermonuclear fusion of hydrogen in its core releasing energy that traverses the star's interior and then radiates into outer space. Almost all naturally occurring elements heavier than helium were created by stars, either via stellar nucleosy ...
Cygnus X-2, super-Eddington mass transfer, and pulsar binaries
... We conclude that the secondary of Cygnus X-2 cannot be a lowmass He white dwarf undergoing a hydrogen-shell flash. 2.4 A star near the end of early massive Case B mass transfer? We saw in Section 2.1 above that a secondary near the onset of early massive Case B mass transfer (i.e. with q & 1 through ...
... We conclude that the secondary of Cygnus X-2 cannot be a lowmass He white dwarf undergoing a hydrogen-shell flash. 2.4 A star near the end of early massive Case B mass transfer? We saw in Section 2.1 above that a secondary near the onset of early massive Case B mass transfer (i.e. with q & 1 through ...
Energy Production in Stars
... nlentioned above, that all elements up to boron are disintegrated by proton bombardment (n-emission!) rather than built up (by radiative capture). The instability of Be' reduces the formation of heavier elements still further. The production of neutrons in stars is likewise negligible. The heavier e ...
... nlentioned above, that all elements up to boron are disintegrated by proton bombardment (n-emission!) rather than built up (by radiative capture). The instability of Be' reduces the formation of heavier elements still further. The production of neutrons in stars is likewise negligible. The heavier e ...
in search of antimatter in the universe
... Nuclei (AGN) (See title, Figure 4,5) These colossal jets originate from the central super-massive black hole of the galaxy, flying through the galaxy around them at speeds close to the speed of light. It is possible that these jets contain electrons and positrons, meaning it is likely that Positroni ...
... Nuclei (AGN) (See title, Figure 4,5) These colossal jets originate from the central super-massive black hole of the galaxy, flying through the galaxy around them at speeds close to the speed of light. It is possible that these jets contain electrons and positrons, meaning it is likely that Positroni ...
NASA FUSE Satellite Solves the Case of the Missing Deuterium
... atoms within a hundred light years of the sun and values as low as 5 parts per million elsewhere. When a region is disturbed by a supernova or hot stars, dust grains are vaporized, releasing deuterium atoms back into a gas phase. FUSE detects high deuterium levels in such regions. Primordial deuteri ...
... atoms within a hundred light years of the sun and values as low as 5 parts per million elsewhere. When a region is disturbed by a supernova or hot stars, dust grains are vaporized, releasing deuterium atoms back into a gas phase. FUSE detects high deuterium levels in such regions. Primordial deuteri ...
Variable Stars – II. Pulsating stars
... second overtone, etc. In fact – and this is very important – all of these modes of variation can be excited at the same time. A star is more analogous to an open-at-one-end organ pipe (see sketch). A node (no movement) exists at the centre of the star (of course – the star is symmetric) and an antin ...
... second overtone, etc. In fact – and this is very important – all of these modes of variation can be excited at the same time. A star is more analogous to an open-at-one-end organ pipe (see sketch). A node (no movement) exists at the centre of the star (of course – the star is symmetric) and an antin ...
CH14.AST1001.S15.EDS
... move faster as they are squeezed into a very small space. • As a white dwarf's mass approaches 1.4MSun, its electrons must move at nearly the speed of light. • Because nothing can move faster than light, a white dwarf cannot be more massive than 1.4MSun, the white dwarf limit (also known as the Chan ...
... move faster as they are squeezed into a very small space. • As a white dwarf's mass approaches 1.4MSun, its electrons must move at nearly the speed of light. • Because nothing can move faster than light, a white dwarf cannot be more massive than 1.4MSun, the white dwarf limit (also known as the Chan ...
Option D – Astrophysics
... In the course of one day, the Earth’s rotation causes our view of the stars to revolve through 360° but, of course, during the day we are not able to see the stars because of the light from the Sun. (Radio astronomers do not have this problem.) Our night-time view changes slightly from one night to ...
... In the course of one day, the Earth’s rotation causes our view of the stars to revolve through 360° but, of course, during the day we are not able to see the stars because of the light from the Sun. (Radio astronomers do not have this problem.) Our night-time view changes slightly from one night to ...
NSDL/NSTA Web Seminar: Celebrating Astronomy: A Star`s Story
... • Smaller individual clumps may form single stars, binary stars, multiple star systems, planetary systems • A star’s life and death depend on: - how much fuel (mass) they have available - how quickly they expend their energy http://nsdl.org ...
... • Smaller individual clumps may form single stars, binary stars, multiple star systems, planetary systems • A star’s life and death depend on: - how much fuel (mass) they have available - how quickly they expend their energy http://nsdl.org ...
1 Introduction - High Point University
... between permitted electron energy levels are absorbed (and later re-emitted in random directions). Thus, when astronomers take spectra of the sun and other stars they see an absorption spectrum due to the absorption of the ...
... between permitted electron energy levels are absorbed (and later re-emitted in random directions). Thus, when astronomers take spectra of the sun and other stars they see an absorption spectrum due to the absorption of the ...
Chapter14 The Bizarre Stellar Graveyard-pptx
... X-Ray Bursts • Matter accreting onto a neutron star can eventually become hot enough for helium to fuse. • The sudden onset of fusion produces a burst of X rays. ...
... X-Ray Bursts • Matter accreting onto a neutron star can eventually become hot enough for helium to fuse. • The sudden onset of fusion produces a burst of X rays. ...
Test 3 Review Clicker Questions
... Astronomers use a distance of 10 parsecs (about 32 light-years) as a standard for specifying and comparing the brightnesses of stars. ...
... Astronomers use a distance of 10 parsecs (about 32 light-years) as a standard for specifying and comparing the brightnesses of stars. ...
Type II supernova
A Type II supernova (plural: supernovae or supernovas) results from the rapid collapse and violent explosion of a massive star. A star must have at least 8 times, and no more than 40–50 times, the mass of the Sun (M☉) for this type of explosion. It is distinguished from other types of supernovae by the presence of hydrogen in its spectrum. Type II supernovae are mainly observed in the spiral arms of galaxies and in H II regions, but not in elliptical galaxies.Stars generate energy by the nuclear fusion of elements. Unlike the Sun, massive stars possess the mass needed to fuse elements that have an atomic mass greater than hydrogen and helium, albeit at increasingly higher temperatures and pressures, causing increasingly shorter stellar life spans. The degeneracy pressure of electrons and the energy generated by these fusion reactions are sufficient to counter the force of gravity and prevent the star from collapsing, maintaining stellar equilibrium. The star fuses increasingly higher mass elements, starting with hydrogen and then helium, progressing up through the periodic table until a core of iron and nickel is produced. Fusion of iron or nickel produces no net energy output, so no further fusion can take place, leaving the nickel-iron core inert. Due to the lack of energy output allowing outward pressure, equilibrium is broken.When the mass of the inert core exceeds the Chandrasekhar limit of about 1.4 M☉, electron degeneracy alone is no longer sufficient to counter gravity and maintain stellar equilibrium. A cataclysmic implosion takes place within seconds, in which the outer core reaches an inward velocity of up to 23% of the speed of light and the inner core reaches temperatures of up to 100 billion kelvin. Neutrons and neutrinos are formed via reversed beta-decay, releasing about 1046 joules (100 foes) in a ten-second burst. The collapse is halted by neutron degeneracy, causing the implosion to rebound and bounce outward. The energy of this expanding shock wave is sufficient to accelerate the surrounding stellar material to escape velocity, forming a supernova explosion, while the shock wave and extremely high temperature and pressure briefly allow for theproduction of elements heavier than iron. Depending on initial size of the star, the remnants of the core form a neutron star or a black hole. Because of the underlying mechanism, the resulting nova is also described as a core-collapse supernova.There exist several categories of Type II supernova explosions, which are categorized based on the resulting light curve—a graph of luminosity versus time—following the explosion. Type II-L supernovae show a steady (linear) decline of the light curve following the explosion, whereas Type II-P display a period of slower decline (a plateau) in their light curve followed by a normal decay. Type Ib and Ic supernovae are a type of core-collapse supernova for a massive star that has shed its outer envelope of hydrogen and (for Type Ic) helium. As a result, they appear to be lacking in these elements.