Time Dependence of the Charge Transfer Efficiency on the WFPC2
... WFPC2 observations in the outskirts of the globular cluster Omega Cen were used to make the measurements. The F814W filter was employed since it provides the highest S/N determination of CTE (since the stars tend to be red and the background is lower than at F555W, resulting in larger values of CTE ...
... WFPC2 observations in the outskirts of the globular cluster Omega Cen were used to make the measurements. The F814W filter was employed since it provides the highest S/N determination of CTE (since the stars tend to be red and the background is lower than at F555W, resulting in larger values of CTE ...
Runaway collisions in young star clusters – II. Numerical results
... of the cluster, we consider King models with W0 = 3 or 8 (Binney & Tremaine 1987, Section 4.4). We do not enforce tidal truncation because it was shown in GFR04 that this does not affect the central regions which completely dominate the evolution. We refer to GFR04 (section 3 and table 1) for detail ...
... of the cluster, we consider King models with W0 = 3 or 8 (Binney & Tremaine 1987, Section 4.4). We do not enforce tidal truncation because it was shown in GFR04 that this does not affect the central regions which completely dominate the evolution. We refer to GFR04 (section 3 and table 1) for detail ...
PDF only - at www.arxiv.org.
... Table 1 shows a stratification of the 504 planets of our sample by stellar mass. The group of planets orbiting stars with mass below 0.8 MSun is quite sparse, compared with groups orbiting more massive stars. The subgroup for 0.8<= MSun <=1.2 contains 282 planets, almost four times the number of pla ...
... Table 1 shows a stratification of the 504 planets of our sample by stellar mass. The group of planets orbiting stars with mass below 0.8 MSun is quite sparse, compared with groups orbiting more massive stars. The subgroup for 0.8<= MSun <=1.2 contains 282 planets, almost four times the number of pla ...
Investigating Black Hole Kicks
... ([29]). In both cases, the accreting star can be either a neutron star or a black hole. F HMXB: the donor is a young and massive O/B star with strong winds that sustain the accretion. The orbital periods range from a few hours to several hundreds days. The spectra have characteristic temperatures kB ...
... ([29]). In both cases, the accreting star can be either a neutron star or a black hole. F HMXB: the donor is a young and massive O/B star with strong winds that sustain the accretion. The orbital periods range from a few hours to several hundreds days. The spectra have characteristic temperatures kB ...
Document
... 4–13×109 years: very slow evolution 13×109 years: slight increase UV (post-AGB stars and very hot white dwarfs) 4000 Å break: after 107 years, opacity H ↔ H–, useful to determine redshift and galaxy type ...
... 4–13×109 years: very slow evolution 13×109 years: slight increase UV (post-AGB stars and very hot white dwarfs) 4000 Å break: after 107 years, opacity H ↔ H–, useful to determine redshift and galaxy type ...
Confronting predictions of the galaxy stellar mass function with
... the amplitude of mass fluctuations σ 8 = 0.8, spectral index ns = 0.96, cosmological constant parameter = 0.74, mass density parameter m = 0.26, baryon density parameter b = 0.044 and h = 0.72 (Hubble’s constant in units of 100 km s−1 Mpc−1 ; WMAP5) for MassiveBlack. For MassiveBlack-II we inst ...
... the amplitude of mass fluctuations σ 8 = 0.8, spectral index ns = 0.96, cosmological constant parameter = 0.74, mass density parameter m = 0.26, baryon density parameter b = 0.044 and h = 0.72 (Hubble’s constant in units of 100 km s−1 Mpc−1 ; WMAP5) for MassiveBlack. For MassiveBlack-II we inst ...
Gaseous Planets, Protostars And Young Brown Dwarfs
... mass loss may have occurred for these objects. Concerning star formation, geometrical effects in protostar core collapse are examined by comparing 1D and 3D calculations. Spherical collapse is shown to significantly overestimate the core inner density and temperature and thus to yield incorrect init ...
... mass loss may have occurred for these objects. Concerning star formation, geometrical effects in protostar core collapse are examined by comparing 1D and 3D calculations. Spherical collapse is shown to significantly overestimate the core inner density and temperature and thus to yield incorrect init ...
Session 1: Stellar winds, diagnostics across the electromagnetic
... seven very luminous WNL stars is found in the Large Magellanic Cloud, disregarding all objects with indications of binarity. In the Small Magellanic Cloud (SMC) the fraction of confirmed binaries is high. We analyzed the composite WN+O spectra as such and obtained very high luminosities for the WN c ...
... seven very luminous WNL stars is found in the Large Magellanic Cloud, disregarding all objects with indications of binarity. In the Small Magellanic Cloud (SMC) the fraction of confirmed binaries is high. We analyzed the composite WN+O spectra as such and obtained very high luminosities for the WN c ...
The evolution and explosion of massive stars
... ideal-gas entropy depends on T 3/2/ , Eq. (6) also implies that more massive stars will have higher central entropy. This too is a characteristic that persists throughout the evolution despite the fact that the pressure at late times is not ideal. Consequently lighter stars tend to converge more i ...
... ideal-gas entropy depends on T 3/2/ , Eq. (6) also implies that more massive stars will have higher central entropy. This too is a characteristic that persists throughout the evolution despite the fact that the pressure at late times is not ideal. Consequently lighter stars tend to converge more i ...
the fragmentation of magnetized, massive star-forming
... the total stellar population, but their numbers belie their impact. Both the total luminosity and the ionizing luminosity of a star are highly super-linear functions of mass. Thus, massive stars have a much stronger impact on their birth environments than low-mass stars do. Since most stars form in ...
... the total stellar population, but their numbers belie their impact. Both the total luminosity and the ionizing luminosity of a star are highly super-linear functions of mass. Thus, massive stars have a much stronger impact on their birth environments than low-mass stars do. Since most stars form in ...
Accretion Disk Assembly During Common Envelope Evolution
... and pressure, is fed in the +x-direction from the −x boundary. This profile is in hydrostatic equilibrium with a vertical (ŷ), external y−2 gravitational acceleration representing the gravity of the enclosed mass of the primary star. The code and methodology are described in detail in MacLeod et al ...
... and pressure, is fed in the +x-direction from the −x boundary. This profile is in hydrostatic equilibrium with a vertical (ŷ), external y−2 gravitational acceleration representing the gravity of the enclosed mass of the primary star. The code and methodology are described in detail in MacLeod et al ...
Mark scheme - Unit A183/02 - Module P7 - Higher tier
... If there is at least one tick, ignore crosses and other markings. If there are no ticks, accept clear, unambiguous indications, e.g. shading or crosses. Credit should be given according to the instructions given in the guidance column for the question. If more boxes are ticked than there are correct ...
... If there is at least one tick, ignore crosses and other markings. If there are no ticks, accept clear, unambiguous indications, e.g. shading or crosses. Credit should be given according to the instructions given in the guidance column for the question. If more boxes are ticked than there are correct ...
BD−21 3873: another yellow-symbiotic barium star
... Abstract. An abundance analysis of the yellow symbiotic system BD−21◦ 3873 reveals it to be a metal-poor K-giant ([Fe/H] = −1.3) which is enriched in the heavy s-process elements. In that respect, this star appears to be a twin of AG Dra, another yellow symbiotic system analyzed in a previous paper ...
... Abstract. An abundance analysis of the yellow symbiotic system BD−21◦ 3873 reveals it to be a metal-poor K-giant ([Fe/H] = −1.3) which is enriched in the heavy s-process elements. In that respect, this star appears to be a twin of AG Dra, another yellow symbiotic system analyzed in a previous paper ...
WFIRSTSurveyScience
... objects, the significant extinction and reddening, and the excess emission due to accretion processes and circumstellar dust. Nevertheless, it is possible to disentangle the complexities of these effects with a combination of multi-color photometry and spectroscopy. For young stellar objects, Y-J is ...
... objects, the significant extinction and reddening, and the excess emission due to accretion processes and circumstellar dust. Nevertheless, it is possible to disentangle the complexities of these effects with a combination of multi-color photometry and spectroscopy. For young stellar objects, Y-J is ...
Age dating stellar populations in the near infrared
... burning core of fast rotating stars. At high rotational velocities, stars evolve as if they were more massive, and as such explode in core collapse supernova before reaching the RSG phase. At rotation velocities above 500 km s−1 this effect becomes significant, lowering the mass of the first RSG to ...
... burning core of fast rotating stars. At high rotational velocities, stars evolve as if they were more massive, and as such explode in core collapse supernova before reaching the RSG phase. At rotation velocities above 500 km s−1 this effect becomes significant, lowering the mass of the first RSG to ...
A Simple Model for r-Process Scatter and Halo Evolution
... (2000)). Nevertheless, the fact that the heavy r-process elements agree so well with each other is stunning, given that this star could well have abundances that reflect the nucleosynthesis of a single supernova, while the solar abundances average over many generations of supernovae. The strong impl ...
... (2000)). Nevertheless, the fact that the heavy r-process elements agree so well with each other is stunning, given that this star could well have abundances that reflect the nucleosynthesis of a single supernova, while the solar abundances average over many generations of supernovae. The strong impl ...
The Big Bang - Community Resources for Science
... Notice that none of the most common elements go past iron. How did all the elements heavier than iron find their way to Earth? Did they come from the sun or a star like the sun? No, scientists know that stars like the sun can only make the elements through iron and then fizzle out. Did these element ...
... Notice that none of the most common elements go past iron. How did all the elements heavier than iron find their way to Earth? Did they come from the sun or a star like the sun? No, scientists know that stars like the sun can only make the elements through iron and then fizzle out. Did these element ...
Effects of color superconductivity on the nucleation of quark matter in
... in the value of Nc is expected to be within one or two orders of magnitude. In any case, all the qualitative features of our scenario will be not affected by the uncertainty in the value of Nc . In order to explore the astrophysical implications of the nucleation, we introduce the concept of critical ...
... in the value of Nc is expected to be within one or two orders of magnitude. In any case, all the qualitative features of our scenario will be not affected by the uncertainty in the value of Nc . In order to explore the astrophysical implications of the nucleation, we introduce the concept of critical ...
The relation among black holes, their host galaxies and AGN activity
... feedback effects (star form., AGN), they form later and take more time to grow. See also Merloni 2004. ...
... feedback effects (star form., AGN), they form later and take more time to grow. See also Merloni 2004. ...
arXiv:astro-ph/0411296v1 11 Nov 2004
... SiC is thought to be a common dust component in carbon stars (Speck et al. 1997), it results in a feature which peaks at 11.3 µm and is too narrow to fit the broad 12 µm ‘plateau’ feature. However, in the absence of an alternative identification, we have used α-SiC optical constants (Pègouriè 1988 ...
... SiC is thought to be a common dust component in carbon stars (Speck et al. 1997), it results in a feature which peaks at 11.3 µm and is too narrow to fit the broad 12 µm ‘plateau’ feature. However, in the absence of an alternative identification, we have used α-SiC optical constants (Pègouriè 1988 ...
Review for final
... 2. Describe an astrolabe, and explain its importance to sailors. 3. Explain right ascension and declination as parts of a coordinate system, and explain why do we need them to locate celestial objects. Be sure to know their units. 4. Apply the method of right ascension and declination to find celest ...
... 2. Describe an astrolabe, and explain its importance to sailors. 3. Explain right ascension and declination as parts of a coordinate system, and explain why do we need them to locate celestial objects. Be sure to know their units. 4. Apply the method of right ascension and declination to find celest ...
Black Hole Formation
... above upper bound may be formed, but these shed most of their mass during the initial stages of their evolutions, such that there is an effective upperbound on the mass of a black holes formed in supernova explosions. • Supermassive black holes contain between 105 and 1010 solar masses. They are be ...
... above upper bound may be formed, but these shed most of their mass during the initial stages of their evolutions, such that there is an effective upperbound on the mass of a black holes formed in supernova explosions. • Supermassive black holes contain between 105 and 1010 solar masses. They are be ...
Core Formation in Giant Gaseous Protoplanets
... enough to let the grains survive. We follow the silicate grains as they grow and sediment towards the center of the protoplanet. In convective regions, the grains are carried by the convective eddies until they grow large enough to decouple from the gas and settle to the center. We find that once gr ...
... enough to let the grains survive. We follow the silicate grains as they grow and sediment towards the center of the protoplanet. In convective regions, the grains are carried by the convective eddies until they grow large enough to decouple from the gas and settle to the center. We find that once gr ...
11.3 MB PDF file
... qualities of a spectrometer. A few years ago it would have been necessary to use compressed gas to scan the interferometer, but we use the extremely stable servo-controlled piezoelectric system developed by Hicks et al. (1974, J. Phys. E. Sei. Instrum. 7, 27) at Imperial College in London. Fig. 2 sh ...
... qualities of a spectrometer. A few years ago it would have been necessary to use compressed gas to scan the interferometer, but we use the extremely stable servo-controlled piezoelectric system developed by Hicks et al. (1974, J. Phys. E. Sei. Instrum. 7, 27) at Imperial College in London. Fig. 2 sh ...
Main sequence
In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hertzsprung and Henry Norris Russell. Stars on this band are known as main-sequence stars or ""dwarf"" stars.After a star has formed, it generates thermal energy in the dense core region through the nuclear fusion of hydrogen atoms into helium. During this stage of the star's lifetime, it is located along the main sequence at a position determined primarily by its mass, but also based upon its chemical composition and other factors. All main-sequence stars are in hydrostatic equilibrium, where outward thermal pressure from the hot core is balanced by the inward pressure of gravitational collapse from the overlying layers. The strong dependence of the rate of energy generation in the core on the temperature and pressure helps to sustain this balance. Energy generated at the core makes its way to the surface and is radiated away at the photosphere. The energy is carried by either radiation or convection, with the latter occurring in regions with steeper temperature gradients, higher opacity or both.The main sequence is sometimes divided into upper and lower parts, based on the dominant process that a star uses to generate energy. Stars below about 1.5 times the mass of the Sun (or 1.5 solar masses (M☉)) primarily fuse hydrogen atoms together in a series of stages to form helium, a sequence called the proton–proton chain. Above this mass, in the upper main sequence, the nuclear fusion process mainly uses atoms of carbon, nitrogen and oxygen as intermediaries in the CNO cycle that produces helium from hydrogen atoms. Main-sequence stars with more than two solar masses undergo convection in their core regions, which acts to stir up the newly created helium and maintain the proportion of fuel needed for fusion to occur. Below this mass, stars have cores that are entirely radiative with convective zones near the surface. With decreasing stellar mass, the proportion of the star forming a convective envelope steadily increases, whereas main-sequence stars below 0.4 M☉ undergo convection throughout their mass. When core convection does not occur, a helium-rich core develops surrounded by an outer layer of hydrogen.In general, the more massive a star is, the shorter its lifespan on the main sequence. After the hydrogen fuel at the core has been consumed, the star evolves away from the main sequence on the HR diagram. The behavior of a star now depends on its mass, with stars below 0.23 M☉ becoming white dwarfs directly, whereas stars with up to ten solar masses pass through a red giant stage. More massive stars can explode as a supernova, or collapse directly into a black hole.