Search for Life in the Universe
... • Science evolves: we know today much more than we knew before • But science is also always incomplete ...
... • Science evolves: we know today much more than we knew before • But science is also always incomplete ...
Radiation vs. Gas Pressure, the Stellar Mass
... to suggest strongly that the physics associated with the Eddington limit plays a key role in enforcing a real, practical upper limit on the masses of stars. The specific link seems most likely to be related to instabilities that can occur near the Eddington limit, perhaps similar to the “photon bubb ...
... to suggest strongly that the physics associated with the Eddington limit plays a key role in enforcing a real, practical upper limit on the masses of stars. The specific link seems most likely to be related to instabilities that can occur near the Eddington limit, perhaps similar to the “photon bubb ...
205 Advances in Natural and Applied Sciences, 4(2): 205-209, 2010 ISSN 1995-0772
... neutron star or a black hole formed after collapse of an ordinary star) and a stellar companion, orbit each other at a distance small enough to enable mass transfer from the companion star to the compact object. The transferred matter spirals towards the compact object and forms an “accretion disk” ...
... neutron star or a black hole formed after collapse of an ordinary star) and a stellar companion, orbit each other at a distance small enough to enable mass transfer from the companion star to the compact object. The transferred matter spirals towards the compact object and forms an “accretion disk” ...
Gravitation
... Physicists after Newton realised it was easier to determine for each point in space the total force that would be experienced by a unit mass, that is, 1 kilogram, at that point. This idea slowly developed and in 1849 Michael Faraday, in explaining the interactions between electric charges and betwee ...
... Physicists after Newton realised it was easier to determine for each point in space the total force that would be experienced by a unit mass, that is, 1 kilogram, at that point. This idea slowly developed and in 1849 Michael Faraday, in explaining the interactions between electric charges and betwee ...
Folie 1
... Effective area of optics ~1150 cm2 30 keV CZT geometrical area 4 cm2 Energy resolution 1 keV 60 keV Grasp 150 deg*cm2 10 keV ...
... Effective area of optics ~1150 cm2 30 keV CZT geometrical area 4 cm2 Energy resolution 1 keV 60 keV Grasp 150 deg*cm2 10 keV ...
The First Stars in the Universe
... computer simulations mentioned above showed the formation of clumps with masses of several hundred solar masses or more. Our group’s calculations suggest that the predicted masses of the first star-forming clumps are not very sensitive to the assumed cosmological conditions (for example, the exact n ...
... computer simulations mentioned above showed the formation of clumps with masses of several hundred solar masses or more. Our group’s calculations suggest that the predicted masses of the first star-forming clumps are not very sensitive to the assumed cosmological conditions (for example, the exact n ...
Astronomy 401 Lecture 18 Galaxy Interactions Here we briefly
... enhancement will develop only half as fast, and M will be twice as far away by the time the enhancement arises. This means that slow encounters are much more effective at decreasing the speed of an interacting object than fast ones. Dynamical friction explains why the most massive galaxies in cluste ...
... enhancement will develop only half as fast, and M will be twice as far away by the time the enhancement arises. This means that slow encounters are much more effective at decreasing the speed of an interacting object than fast ones. Dynamical friction explains why the most massive galaxies in cluste ...
Gravitational and Inertial Mass in General Relativity
... experiment, deviations from M G / M I 1 are smaller than a few parts in 1013 , and planned satellite tests (STEP) are expected to explore this to 1 part in 1018 [Will, 2005]. In contrast, the experimental evidence for the so-called strong equivalence principle (SEP) is spotty. Simply stated, SEP a ...
... experiment, deviations from M G / M I 1 are smaller than a few parts in 1013 , and planned satellite tests (STEP) are expected to explore this to 1 part in 1018 [Will, 2005]. In contrast, the experimental evidence for the so-called strong equivalence principle (SEP) is spotty. Simply stated, SEP a ...
Walk Softly When Exploring the Dark Side of the Universe Karl Gebhardt
... Lonestar to the rescue! The problem is that we need very complicated models to include both black hole and the dark matter. This would take 10 years in the old mode. This would not be possible without supercomputers. I use the TACC (Texas Advanced Computing Center) and the 5800 (called Lonestar ...
... Lonestar to the rescue! The problem is that we need very complicated models to include both black hole and the dark matter. This would take 10 years in the old mode. This would not be possible without supercomputers. I use the TACC (Texas Advanced Computing Center) and the 5800 (called Lonestar ...
An introduction to the mechanics of black holes
... The theorem was stated originally in 4 dimensions but it is actually valid in any dimension n ≥ 3. In order to understand the second requirement, let us remind some definitions. The future domain of dependence D + (Σ) of an hypersurface Σ is the set of points p in the manifold for which every causal ...
... The theorem was stated originally in 4 dimensions but it is actually valid in any dimension n ≥ 3. In order to understand the second requirement, let us remind some definitions. The future domain of dependence D + (Σ) of an hypersurface Σ is the set of points p in the manifold for which every causal ...
Testing the Universality of Free Fall for Charged Particles in
... where κ = κg2 − κi2 . A charge–induced violation of the UFF is encoded in the parameter κ. Only if the electromagnetic energy of charged particles contributes in the same way to their inertial and the gravitational mass (which means κg = κi ), then there will be no charge–induced violation of the UF ...
... where κ = κg2 − κi2 . A charge–induced violation of the UFF is encoded in the parameter κ. Only if the electromagnetic energy of charged particles contributes in the same way to their inertial and the gravitational mass (which means κg = κi ), then there will be no charge–induced violation of the UF ...
Rotational effects on the oscillation frequencies of newly born proto
... gradients that develop in the stellar interior. The models used in FMP were developed in Pons et al. (1999;2001) and describe the stellar evolution in terms of a sequence of equilibrium configurations; this ‘quasi-stationary’ approach has been shown to become appropriate a few tenths of seconds afte ...
... gradients that develop in the stellar interior. The models used in FMP were developed in Pons et al. (1999;2001) and describe the stellar evolution in terms of a sequence of equilibrium configurations; this ‘quasi-stationary’ approach has been shown to become appropriate a few tenths of seconds afte ...
Lectures 6-8: Solar nebula theory
... o Once grains are large enough that gravity is important, accretion rate increases dramatically. o If critical size is achieved, a planetesimal will grow rapidly. Less massive objects grow at a much smaller rate. o Model calculation suggest that the first large size objects to form are planetesim ...
... o Once grains are large enough that gravity is important, accretion rate increases dramatically. o If critical size is achieved, a planetesimal will grow rapidly. Less massive objects grow at a much smaller rate. o Model calculation suggest that the first large size objects to form are planetesim ...
Soft Hair on Black Holes - Physics (APS)
... (ii) Black holes have a lush head of “soft hair.” The information loss argument assumes that static black holes are nearly bald; i.e., they are characterized solely by their mass M, charge Q, and angular momentum J. The no-hair theorem [41] indeed shows that static black holes are characterized by M ...
... (ii) Black holes have a lush head of “soft hair.” The information loss argument assumes that static black holes are nearly bald; i.e., they are characterized solely by their mass M, charge Q, and angular momentum J. The no-hair theorem [41] indeed shows that static black holes are characterized by M ...
Subrahmanyan Chandrasekhar
... Traveling by ship in 1930 to begin his Ph.D. at Cambridge University, he had calculated a number. In his honor this number is now called The Chandrasekhar Limit: its value is 1.4. This number determines the fate of stars. Chandrasekhar published his result in 1931 in the Astrophysical Journal. In se ...
... Traveling by ship in 1930 to begin his Ph.D. at Cambridge University, he had calculated a number. In his honor this number is now called The Chandrasekhar Limit: its value is 1.4. This number determines the fate of stars. Chandrasekhar published his result in 1931 in the Astrophysical Journal. In se ...
Slide 1
... Magnetic torque can reduce rotation of star if ionization is high (frozen-in magn. field). Process needs ionized gas that may not be available at large distances from the protoSun. Protoplanetary disks apparently do not extend all the way down to the surface of the star. Magnetic interactions at the ...
... Magnetic torque can reduce rotation of star if ionization is high (frozen-in magn. field). Process needs ionized gas that may not be available at large distances from the protoSun. Protoplanetary disks apparently do not extend all the way down to the surface of the star. Magnetic interactions at the ...
Vibrational instability of Population III very massive mainsequence
... M denotes the total mass lost during the unstable stage. The one for 500 M is roughly consistent with the result of Baraffe et al., 25 M . Besides, in their result, the ratio of the mass-loss amount to the total stellar mass increases from 120 to 500 M . Extrapolating from their result, significa ...
... M denotes the total mass lost during the unstable stage. The one for 500 M is roughly consistent with the result of Baraffe et al., 25 M . Besides, in their result, the ratio of the mass-loss amount to the total stellar mass increases from 120 to 500 M . Extrapolating from their result, significa ...
Boson Stars: Alternatives to primordial black holes?
... Astronomy Centre, School of Chemistry, Physics and Environmental Science, University of Sussex, Falmer, Brighton BN1 9QJ, United Kingdom, (February 6, 2008) The present surge for the astrophysical relevance of boson stars stems from the speculative possibility that these compact objects could provid ...
... Astronomy Centre, School of Chemistry, Physics and Environmental Science, University of Sussex, Falmer, Brighton BN1 9QJ, United Kingdom, (February 6, 2008) The present surge for the astrophysical relevance of boson stars stems from the speculative possibility that these compact objects could provid ...