An interesting nebular object in LDN 288
... (b in Fig.5b). There is another star with a jet in its vicinity (object c in the Fig.5b). c. SNO 69 [3] (see Fig.5c). This looks like a trapezium-like system, consisting of four stars. There are spiral jets, at the ends of which there are condensations. It seems that not only the jets, but also the ...
... (b in Fig.5b). There is another star with a jet in its vicinity (object c in the Fig.5b). c. SNO 69 [3] (see Fig.5c). This looks like a trapezium-like system, consisting of four stars. There are spiral jets, at the ends of which there are condensations. It seems that not only the jets, but also the ...
Sample pages 1 PDF
... there is an exchange of material between the core and the photospheres in such stars due to the nature of their convective cores. Some AGB stars have photospheres that are heavily obscured by carbon dust, which indicates the nature of their cores. Others have high incidences of oxygen and the spectr ...
... there is an exchange of material between the core and the photospheres in such stars due to the nature of their convective cores. Some AGB stars have photospheres that are heavily obscured by carbon dust, which indicates the nature of their cores. Others have high incidences of oxygen and the spectr ...
answer
... their “lives” on the main sequence than they spend as red giant stars. ANS: When any individual star becomes a red giant, its luminosity will be greater than it was when the star was on the main sequence; hence as a red giant the star must burn up its fuel at a faster rate than when it was on the ma ...
... their “lives” on the main sequence than they spend as red giant stars. ANS: When any individual star becomes a red giant, its luminosity will be greater than it was when the star was on the main sequence; hence as a red giant the star must burn up its fuel at a faster rate than when it was on the ma ...
A Compact Central Object in the Supernova Remnant Kes 79
... The blackbody spectrum strongly suggests that the central point source in Kes 79 is not a foreground star or background AGN, as are the other unresolved sources in Figure 1. The central location and similarity to other recently-discovered objects (see list 2 below) indicate that this is probably a n ...
... The blackbody spectrum strongly suggests that the central point source in Kes 79 is not a foreground star or background AGN, as are the other unresolved sources in Figure 1. The central location and similarity to other recently-discovered objects (see list 2 below) indicate that this is probably a n ...
White dwarf cooling sequences and cosmochronology
... the size of MH well below this critical value, this source can be neglected. Fortunately, when neutrino emission becomes dominant, the different thermal structures converge to a unique one, granting the uniformity of the models with log(L/L ) ≤ −1.5. Furthermore, since the time necessary to reach t ...
... the size of MH well below this critical value, this source can be neglected. Fortunately, when neutrino emission becomes dominant, the different thermal structures converge to a unique one, granting the uniformity of the models with log(L/L ) ≤ −1.5. Furthermore, since the time necessary to reach t ...
1 Introduction - University of Amsterdam
... role of massive stars in our universe – it is pivotal to understand the formation and evolution of massive stars. Perhaps surprisingly so, little is known about these processes. The formation of massive stars – rare events in the present-day universe – takes place deep inside dusty interstellar clou ...
... role of massive stars in our universe – it is pivotal to understand the formation and evolution of massive stars. Perhaps surprisingly so, little is known about these processes. The formation of massive stars – rare events in the present-day universe – takes place deep inside dusty interstellar clou ...
USRA - MSU Solar Physics
... near the speed of light out of the core result from the infalling matter and run into the outer layers of the star’s atmosphere and other material in the immediate vicinity creating shock waves which are seen as the burst and the afterglow. The supernova reaches its peak weeks after the GRB. II) The ...
... near the speed of light out of the core result from the infalling matter and run into the outer layers of the star’s atmosphere and other material in the immediate vicinity creating shock waves which are seen as the burst and the afterglow. The supernova reaches its peak weeks after the GRB. II) The ...
Downloadable Full Text
... neutron-capture elements (Figure 1). Our abundance analysis (see Methods) finds that these seven stars span a factor of 10 in metallicity centered at [Fe/H] = –2.5, and all seven stars are significantly enhanced in neutron-capture elements. Their [Eu/Fe] abundances are the highest found in any dwarf ...
... neutron-capture elements (Figure 1). Our abundance analysis (see Methods) finds that these seven stars span a factor of 10 in metallicity centered at [Fe/H] = –2.5, and all seven stars are significantly enhanced in neutron-capture elements. Their [Eu/Fe] abundances are the highest found in any dwarf ...
11-Massive Stars
... The outflows are difficult to study because multiple outflows often emanate from the same large scale core. Clusters of stars form simultaneously in a core and the outflows originate from different protostars. For example, at least three molecular outflows are resolved in the core containing IRAS 05 ...
... The outflows are difficult to study because multiple outflows often emanate from the same large scale core. Clusters of stars form simultaneously in a core and the outflows originate from different protostars. For example, at least three molecular outflows are resolved in the core containing IRAS 05 ...
Star Formation in the Galaxy, An Observational Overview
... by Hayashi (Hayasi & Hoshi 1961). The inner core both gains mass (from the continual production of helium in the hydrogen burning shell) and contracts until fusion reactions involving helium restore a temporary equilibrium in which gravity is again balanced by internal pressure. After this phase suc ...
... by Hayashi (Hayasi & Hoshi 1961). The inner core both gains mass (from the continual production of helium in the hydrogen burning shell) and contracts until fusion reactions involving helium restore a temporary equilibrium in which gravity is again balanced by internal pressure. After this phase suc ...
A very massive runaway star from Cygnus OB2⋆
... v∗ is the spatial velocity of the star. The distance given in Eq. (5) assumes that the bow shock is bound by shock fronts on both sides. In reality, the non-zero cooling time of the shocked stellar wind builds up a thick layer of low-density, high-temperature gas between the reverse shock on the ste ...
... v∗ is the spatial velocity of the star. The distance given in Eq. (5) assumes that the bow shock is bound by shock fronts on both sides. In reality, the non-zero cooling time of the shocked stellar wind builds up a thick layer of low-density, high-temperature gas between the reverse shock on the ste ...
NCEA Level 2 Earth and Space Science (91192) 2013
... Aldebaran birth explained with associated energy changes: GMC collapsing changes Gravitational Potential Energy into heat energy. When this heat energy temperature reaches about 1 000 000 K, nuclear fusion of hydrogen into helium occurs. Aldebaran was once a main sequence star; this is where Aldebar ...
... Aldebaran birth explained with associated energy changes: GMC collapsing changes Gravitational Potential Energy into heat energy. When this heat energy temperature reaches about 1 000 000 K, nuclear fusion of hydrogen into helium occurs. Aldebaran was once a main sequence star; this is where Aldebar ...
Aspects of Nuclear Physics and Astrophysics - Wiley-VCH
... the environments in which these sources of nucleosynthesis operated. All nuclides, with few exceptions, are synthesized in stars. Therefore, the observed solar system abundances offer powerful clues to stellar history and evolution, and by extension, to the chemical evolution of the Galaxy as a whol ...
... the environments in which these sources of nucleosynthesis operated. All nuclides, with few exceptions, are synthesized in stars. Therefore, the observed solar system abundances offer powerful clues to stellar history and evolution, and by extension, to the chemical evolution of the Galaxy as a whol ...
Stellar radii from long-baseline interferometry
... The cool dwarfs 61 Cyg A and B are the nearest stars in the northern hemisphere. They are a visual binary pair with a very long orbital period (≈ 700 yrs). In 1838, 61 Cyg became the first star whose distance from Earth was estimated accurately (Bessel 1838), shortly before Procyon’s, and it is now k ...
... The cool dwarfs 61 Cyg A and B are the nearest stars in the northern hemisphere. They are a visual binary pair with a very long orbital period (≈ 700 yrs). In 1838, 61 Cyg became the first star whose distance from Earth was estimated accurately (Bessel 1838), shortly before Procyon’s, and it is now k ...
Cosmological Transient Objects
... • At the time of explosion, the supernova can shine brighter than the host galaxy consisting of billions of stars. • In one month, a supernova can emit as much energy as Sun would emit in its entire life span of billions of years. • GRBs: biggest source of gamma-rays in universe and 100 times more e ...
... • At the time of explosion, the supernova can shine brighter than the host galaxy consisting of billions of stars. • In one month, a supernova can emit as much energy as Sun would emit in its entire life span of billions of years. • GRBs: biggest source of gamma-rays in universe and 100 times more e ...
Phases of Stellar Evolution
... A measure of the central condensation for a particular volume is the ratio ρ(r) (the local value of the density) to <ρ(r)> the mean density of the material interior to r. We define U ≡ 3ρ(r)/<ρ(r)> where <ρ(r)> = 3m(r) / 4πr3 One can show: U = d(ln(m(r))/d(ln(r)) = d ln(q) / d ln(r) where q ≡ m(r)/M ...
... A measure of the central condensation for a particular volume is the ratio ρ(r) (the local value of the density) to <ρ(r)> the mean density of the material interior to r. We define U ≡ 3ρ(r)/<ρ(r)> where <ρ(r)> = 3m(r) / 4πr3 One can show: U = d(ln(m(r))/d(ln(r)) = d ln(q) / d ln(r) where q ≡ m(r)/M ...
Spectral Classification: The First Step in Quantitative Spectral Analysis
... “V” type is valid, so iteration is not necessary ...
... “V” type is valid, so iteration is not necessary ...
Stars
... • While stars are in the main sequence, they are fusing hydrogen in their cores. As stars evolve off the main sequence, they begin to fuse helium in their cores and burn hydrogen around the core edges. ...
... • While stars are in the main sequence, they are fusing hydrogen in their cores. As stars evolve off the main sequence, they begin to fuse helium in their cores and burn hydrogen around the core edges. ...
Geoscience Astronomy Formative on Stellar Evolution and
... 22. What will be the final stage in the sun’s life cycle? a. white dwarf c. planetary nebula b. red giant d. black dwarf 23. Our galaxy is called the ____. a. Local Group c. Andromeda b. Orion d. Milky Way 24. Which of the following is NOT a type of galaxy? a. nebular c. spiral b. irregular d. ellip ...
... 22. What will be the final stage in the sun’s life cycle? a. white dwarf c. planetary nebula b. red giant d. black dwarf 23. Our galaxy is called the ____. a. Local Group c. Andromeda b. Orion d. Milky Way 24. Which of the following is NOT a type of galaxy? a. nebular c. spiral b. irregular d. ellip ...
@let@token Stellar Oscillations: Pulsations of Stars Throughout the
... processes take place in the outer layer of hydrogen-rich material, which consists of a radiative layer overlaid by a convective envelope. The radiative layer contributes to mode damping, because its opacity decreases upon compression and the amplitude of the Lagrangian pressure perturbation increase ...
... processes take place in the outer layer of hydrogen-rich material, which consists of a radiative layer overlaid by a convective envelope. The radiative layer contributes to mode damping, because its opacity decreases upon compression and the amplitude of the Lagrangian pressure perturbation increase ...
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.