Cosmological Implications of Trace
... for effects commonly attributed to unconventional forms of dark energy or dark matter, often called ΛCDM . For example, the strong jetting observed in AGNs can be created if matter ionizes near the event horizon of a positively tracecharged black hole. Newly ionized protons feel a strong Coulomb rep ...
... for effects commonly attributed to unconventional forms of dark energy or dark matter, often called ΛCDM . For example, the strong jetting observed in AGNs can be created if matter ionizes near the event horizon of a positively tracecharged black hole. Newly ionized protons feel a strong Coulomb rep ...
General relativistic spectra of accretion discs around rapidly
... result, the plotted spectra for these two cases lie almost on top of each other. However, for i ¼ 08 the flux corresponding to the massshed configuration is slightly higher than that for V ¼ 0, while the case is opposite at higher inclinations. This is a result of the inclination dependence of the ð ...
... result, the plotted spectra for these two cases lie almost on top of each other. However, for i ¼ 08 the flux corresponding to the massshed configuration is slightly higher than that for V ¼ 0, while the case is opposite at higher inclinations. This is a result of the inclination dependence of the ð ...
White dwarf cooling sequences and cosmochronology
... 5. THE AGE OF THE GALACTIC DISK A common picture of the formation of the Milky Way is that spiral galaxies form as a consequence of the gas cooling inside a spinning dark matter halo. In a first stage, the gas collapses in a dynamical time scale that lasts for several hundred million years, leaving ...
... 5. THE AGE OF THE GALACTIC DISK A common picture of the formation of the Milky Way is that spiral galaxies form as a consequence of the gas cooling inside a spinning dark matter halo. In a first stage, the gas collapses in a dynamical time scale that lasts for several hundred million years, leaving ...
Active X-ray Optics - High Energy Astrophysics Division
... could keep hydrogen ionized, were clearly over by z=6.4 (an Age of the Universe of 0.87 Gyr) as we see quasars, Gamma-ray bursts and galaxies already formed then. As quasars show high metal abundances at z=6, there must have been more than one generation of supernovae to create these metals by z=6, ...
... could keep hydrogen ionized, were clearly over by z=6.4 (an Age of the Universe of 0.87 Gyr) as we see quasars, Gamma-ray bursts and galaxies already formed then. As quasars show high metal abundances at z=6, there must have been more than one generation of supernovae to create these metals by z=6, ...
Stellar Metamorphosis as Alternative to Nebular Hypothesis
... momentum loss of the Sun.[5] If the nebular model were correct and all the material in the solar system was formed from a giant spinning gas/dust cloud, then the Sun should have the majority of the angular momentum. This means it should spin much more rapidly. The mathematical models have failed to ...
... momentum loss of the Sun.[5] If the nebular model were correct and all the material in the solar system was formed from a giant spinning gas/dust cloud, then the Sun should have the majority of the angular momentum. This means it should spin much more rapidly. The mathematical models have failed to ...
BLACK HOLES - Science Center of Iowa
... generally predictable ways because of the gravitational attraction between the stars. Scientists knew that if they saw a single star moving as if there were a massive object nearby, but with no other star in evidence, then its invisible companion could be a black hole. Scientists also realized that ...
... generally predictable ways because of the gravitational attraction between the stars. Scientists knew that if they saw a single star moving as if there were a massive object nearby, but with no other star in evidence, then its invisible companion could be a black hole. Scientists also realized that ...
ppt file - Universitat de Barcelona
... studying the interaction between the members of these environments Approach and strategy ...
... studying the interaction between the members of these environments Approach and strategy ...
WELCOME TO THE MILKY WAY
... galaxy contains the spiral arms, which are very rich in gas and dust. These spiral arms are about 1,500 ly thick. They also contain the emission nebulae and the young and hot (O and B) giant and supergiant stars that light up the spiral structure (see Fig. 2.1). The Milky Way is surrounded by a halo ...
... galaxy contains the spiral arms, which are very rich in gas and dust. These spiral arms are about 1,500 ly thick. They also contain the emission nebulae and the young and hot (O and B) giant and supergiant stars that light up the spiral structure (see Fig. 2.1). The Milky Way is surrounded by a halo ...
{2.} and {4.}
... Constellations are the way that many learn about the sky and help as a memory aid to the stars that form the figures, the constellations did organize this endless wonder, our sky. As scientist looked longer at our sky they categorized stars and found that they could predict their movement, making an ...
... Constellations are the way that many learn about the sky and help as a memory aid to the stars that form the figures, the constellations did organize this endless wonder, our sky. As scientist looked longer at our sky they categorized stars and found that they could predict their movement, making an ...
Links Between Pulsation and Line-Driven Mass Loss in Massive Stars
... • Stellar Wind – Driven by line-scattering of star’s radiation – Rotation can lead to Wind Compressed Disk (WCD) – But still lacks angular momentum for orbit ...
... • Stellar Wind – Driven by line-scattering of star’s radiation – Rotation can lead to Wind Compressed Disk (WCD) – But still lacks angular momentum for orbit ...
On the possibility of a helium white dwarf donor in the presumed
... Abstract. 2S 0918–549 is a low-mass X-ray binary (LMXB) with a low optical to X-ray flux ratio. Probably it is an ultracompact binary with an orbital period shorter than 60 min. Such binaries cannot harbor hydrogen rich donor stars. As with other (sometimes confirmed) ultracompact LMXBs, 2S 0918–549 ...
... Abstract. 2S 0918–549 is a low-mass X-ray binary (LMXB) with a low optical to X-ray flux ratio. Probably it is an ultracompact binary with an orbital period shorter than 60 min. Such binaries cannot harbor hydrogen rich donor stars. As with other (sometimes confirmed) ultracompact LMXBs, 2S 0918–549 ...
30.4 Gravitational collapse & early protostellar evolution I (HB)
... the protostar can be described by its entropy profile s(Mr), reflecting the changing conditions at the accretion shock. - Since s represents heat content of each added mass shell, an increase of s(MR) causes a swelling of the protostar. - In the absence of nuclear burning, an increasing s(Mr) arises ...
... the protostar can be described by its entropy profile s(Mr), reflecting the changing conditions at the accretion shock. - Since s represents heat content of each added mass shell, an increase of s(MR) causes a swelling of the protostar. - In the absence of nuclear burning, an increasing s(Mr) arises ...
Astronomy Astrophysics - Utrecht University Repository
... distributed on an increasingly wider range of ∆R with increasing near-IR excess. This suggests that the maximum amplitude of optical variability a sample star can display is related to the near-IR excess. Figure 3 also shows low amplitude stars with large near-IR excess. If indeed these are variable ...
... distributed on an increasingly wider range of ∆R with increasing near-IR excess. This suggests that the maximum amplitude of optical variability a sample star can display is related to the near-IR excess. Figure 3 also shows low amplitude stars with large near-IR excess. If indeed these are variable ...
Paper II - van Werkhoven, Kenworthy and Mamajek (2014)
... where P0 is the nominal period and Ṗ the time-derivative of the period. This model is fitted to the data using the Nelder–Mead fitting algorithm (Nelder & Mead 1965). Our analysis shows that the bestfitting periods and their amplitudes differ significantly from year to year (see Table 1). Furthermo ...
... where P0 is the nominal period and Ṗ the time-derivative of the period. This model is fitted to the data using the Nelder–Mead fitting algorithm (Nelder & Mead 1965). Our analysis shows that the bestfitting periods and their amplitudes differ significantly from year to year (see Table 1). Furthermo ...
On the onset of runaway stellar collisions in dense star clusters I
... studying young star clusters such as R136, MGG11 and Arches (Massey & Hunter 1998; Figer et al. 2002; McCrady et al. 2005), and young star clusters are thought to be born with high concentration (Merritt et al. 2004). In addition, high concentration is a necessary condition for clusters which can ex ...
... studying young star clusters such as R136, MGG11 and Arches (Massey & Hunter 1998; Figer et al. 2002; McCrady et al. 2005), and young star clusters are thought to be born with high concentration (Merritt et al. 2004). In addition, high concentration is a necessary condition for clusters which can ex ...
The Halo of the Milky Way
... The spheroid population may be triaxial with a major axis oriented 65◦ from the line of sight from the Sun to the Galactic center. This is approximately perpendicular to the Galactic bar. This is surprising since one typically expects bars to have an angular pattern speed larger than could be sustai ...
... The spheroid population may be triaxial with a major axis oriented 65◦ from the line of sight from the Sun to the Galactic center. This is approximately perpendicular to the Galactic bar. This is surprising since one typically expects bars to have an angular pattern speed larger than could be sustai ...
Quasar Formation and Energy Emission in Black Hole Universe
... of the distant quasars have shown that some supermassive black holes were formed when the universe was merely 1-2 billion years after the big bang had taken place [5, 21]. How the supermassive black holes with billions of solar masses were formed so rapidly during the early universe is a great myste ...
... of the distant quasars have shown that some supermassive black holes were formed when the universe was merely 1-2 billion years after the big bang had taken place [5, 21]. How the supermassive black holes with billions of solar masses were formed so rapidly during the early universe is a great myste ...
The role of black holes in galaxy formation and evolution
... The energy that jets pump into cavities in a sound crossing time matches the heat needed to keep the gas in thermal equilibrium if this energy equals to pgasVcav with a scatter of a factor of four39 (Fig. 5a). This proportionality, which extends over four orders of magnitude, suggests a self-regulat ...
... The energy that jets pump into cavities in a sound crossing time matches the heat needed to keep the gas in thermal equilibrium if this energy equals to pgasVcav with a scatter of a factor of four39 (Fig. 5a). This proportionality, which extends over four orders of magnitude, suggests a self-regulat ...
PDF Full-text
... radiation is more difficult to observe, and stellar-model chromosphere and corona codes are not yet capable of predicting the UV, EUV, and X-ray emission of host stars accurately. In this paper, I limit our focus to observations of short wavelength radiation from G-M dwarf stars, in particular to kn ...
... radiation is more difficult to observe, and stellar-model chromosphere and corona codes are not yet capable of predicting the UV, EUV, and X-ray emission of host stars accurately. In this paper, I limit our focus to observations of short wavelength radiation from G-M dwarf stars, in particular to kn ...
observability and uv coverage
... During the imaging process (this volume, C. Hani rst lecture), a single dish telescope can be viewed as a low pass lter with cut-o frequency D= where D is the telescope diameter and is the wavelength. The incoming wavefront is thus spatially ltered by the telescope and all spatial frequencie ...
... During the imaging process (this volume, C. Hani rst lecture), a single dish telescope can be viewed as a low pass lter with cut-o frequency D= where D is the telescope diameter and is the wavelength. The incoming wavefront is thus spatially ltered by the telescope and all spatial frequencie ...
Cygnus X-1
Cygnus X-1 (abbreviated Cyg X-1) is a well-known galactic X-ray source, thought to be a black hole, in the constellation Cygnus. It was discovered in 1964 during a rocket flight and is one of the strongest X-ray sources seen from Earth, producing a peak X-ray flux density of 6977229999999999999♠2.3×10−23 Wm−2 Hz−1 (7003230000000000000♠2.3×103 Jansky). Cygnus X-1 was the first X-ray source widely accepted to be a black hole and it remains among the most studied astronomical objects in its class. The compact object is now estimated to have a mass about 14.8 times the mass of the Sun and has been shown to be too small to be any known kind of normal star, or other likely object besides a black hole. If so, the radius of its event horizon is about 7004440000000000000♠44 km.Cygnus X-1 belongs to a high-mass X-ray binary system about 7019574266339685654♠6070 ly from the Sun that includes a blue supergiant variable star designated HDE 226868 which it orbits at about 0.2 AU, or 20% of the distance from the Earth to the Sun. A stellar wind from the star provides material for an accretion disk around the X-ray source. Matter in the inner disk is heated to millions of degrees, generating the observed X-rays. A pair of jets, arranged perpendicular to the disk, are carrying part of the energy of the infalling material away into interstellar space.This system may belong to a stellar association called Cygnus OB3, which would mean that Cygnus X-1 is about five million years old and formed from a progenitor star that had more than 7001400000000000000♠40 solar masses. The majority of the star's mass was shed, most likely as a stellar wind. If this star had then exploded as a supernova, the resulting force would most likely have ejected the remnant from the system. Hence the star may have instead collapsed directly into a black hole.Cygnus X-1 was the subject of a friendly scientific wager between physicists Stephen Hawking and Kip Thorne in 1975, with Hawking betting that it was not a black hole. He conceded the bet in 1990 after observational data had strengthened the case that there was indeed a black hole in the system. This hypothesis has not been confirmed due to a lack of direct observation but has generally been accepted from indirect evidence.