The Formation of Primordial Luminous Objects - SLAC
... Inflation is a mechanism which was first proposed by Guth (1981) and (in a different way) by Starobinsky (1979, 1980), and has since been included in a number of different “inflationary theories” (see Guth 2004 for a review upon which we base this paragraph). The basic assumption of inflationary mod ...
... Inflation is a mechanism which was first proposed by Guth (1981) and (in a different way) by Starobinsky (1979, 1980), and has since been included in a number of different “inflationary theories” (see Guth 2004 for a review upon which we base this paragraph). The basic assumption of inflationary mod ...
THE HOBBY-EBERLY TELESCOPE CHEMICAL ABUNDANCES OF
... chain reactions. These nucleosynthesis reactions make it indeed possible for a star to self-enrich its atmosphere with Li, but only for a very short period of time before the freshly produced Li burns again. The enrichment can be quite extreme, however, with Li abundances sometimes 1Y2 dex higher th ...
... chain reactions. These nucleosynthesis reactions make it indeed possible for a star to self-enrich its atmosphere with Li, but only for a very short period of time before the freshly produced Li burns again. The enrichment can be quite extreme, however, with Li abundances sometimes 1Y2 dex higher th ...
A Detailed Spectroscopic and Photometric Analysis of DQ White
... Strong molecular absorption bands that appear to originate from some carbon compound have also been reported in several cool white dwarfs (see, e.g. Schmidt et al. 1995; Harris et al. 2003). The detailed model atmosphere and photometric analysis by BRL of some of these objects reveals that in additi ...
... Strong molecular absorption bands that appear to originate from some carbon compound have also been reported in several cool white dwarfs (see, e.g. Schmidt et al. 1995; Harris et al. 2003). The detailed model atmosphere and photometric analysis by BRL of some of these objects reveals that in additi ...
Barium Stars: Theoretical Interpretation
... Barium stars have been a fascinating subject since their discovery by Bidelman & Keenan (1951). Understanding their peculiar abundance patterns has been a challenge for over 50 years. Barium stars show s-process enhancement. However, these stars are giants or main-sequence, far away from the thermal ...
... Barium stars have been a fascinating subject since their discovery by Bidelman & Keenan (1951). Understanding their peculiar abundance patterns has been a challenge for over 50 years. Barium stars show s-process enhancement. However, these stars are giants or main-sequence, far away from the thermal ...
A 25 micron search for Vega-like disks around main
... the 25 µm sample. The stars were selected on the following selection criteria: (1) all stars are within 25 pc of the Sun; (2) a spectral type later than B9 but earlier than M, and only dwarfs of type IV–V or V; (3) a predicted photospheric flux at 60 µm of at least 30 mJy; (4) no (optical) binaries ...
... the 25 µm sample. The stars were selected on the following selection criteria: (1) all stars are within 25 pc of the Sun; (2) a spectral type later than B9 but earlier than M, and only dwarfs of type IV–V or V; (3) a predicted photospheric flux at 60 µm of at least 30 mJy; (4) no (optical) binaries ...
- UCL Discovery
... number of resolution elements to simulations of larger galaxies, like the Milky Way. Mori et al. (1997) simulated the formation of a dwarf galaxy as a monolithic collapse of the gas within a dark matter halo. They demonstrated that due to the small gravitational potential of dwarf galaxies, the supe ...
... number of resolution elements to simulations of larger galaxies, like the Milky Way. Mori et al. (1997) simulated the formation of a dwarf galaxy as a monolithic collapse of the gas within a dark matter halo. They demonstrated that due to the small gravitational potential of dwarf galaxies, the supe ...
Neutron stars as probes of extreme energy density matter
... for. A case in point is RX J1856−3754, the nearest known neutron star. Depending upon the atmospheric model used, the inferred masses vary significantly, although the radii are similar (see table 3). Non-magnetic heavy element atmospheres [23,24] predict spectral features that are not observed. Foll ...
... for. A case in point is RX J1856−3754, the nearest known neutron star. Depending upon the atmospheric model used, the inferred masses vary significantly, although the radii are similar (see table 3). Non-magnetic heavy element atmospheres [23,24] predict spectral features that are not observed. Foll ...
Stellar Structure and Evolution
... the physical properties of the matter in the stars; hence by testing the computed models against observations we are effectively testing the physics that was used to compute the models, often under conditions where it is impossible to carry out tests in the laboratory. This chapter provides an intro ...
... the physical properties of the matter in the stars; hence by testing the computed models against observations we are effectively testing the physics that was used to compute the models, often under conditions where it is impossible to carry out tests in the laboratory. This chapter provides an intro ...
Modeling non-thermal emission from stellar bow shocks
... Mackey et al. (2012) developed stellar evolution models and incorporated the evolving stellar wind into hydrodynamic simulations to simulate the transition of Betelgeuse from the blue supergiant (BSG) phase to the red supergiant (RSG) phase at the late stages of its life. At these phases, massive st ...
... Mackey et al. (2012) developed stellar evolution models and incorporated the evolving stellar wind into hydrodynamic simulations to simulate the transition of Betelgeuse from the blue supergiant (BSG) phase to the red supergiant (RSG) phase at the late stages of its life. At these phases, massive st ...
Chapter 2 Stellar Dynamics in Galaxies
... A system of stars behaves like a fluid, but one with unusual properties. In a normal fluid two-body interactions are crucial in the dynamics, but in contrast star-star encounters are very rare. Instead stellar dynamics is mostly governed by the interaction of individual stars with the mean gravitati ...
... A system of stars behaves like a fluid, but one with unusual properties. In a normal fluid two-body interactions are crucial in the dynamics, but in contrast star-star encounters are very rare. Instead stellar dynamics is mostly governed by the interaction of individual stars with the mean gravitati ...
Cluster formation in molecular clouds – I. Stellar populations, star
... & Anderson 2006). In a turbulent medium, these points are dispersed so that monolithic collapse to form a cluster does not occur. The observations of the Orion cloud suggest that subclustering occurs across large regions of the cloud (Megeath et al. 2012) so that the formation of a cluster would inv ...
... & Anderson 2006). In a turbulent medium, these points are dispersed so that monolithic collapse to form a cluster does not occur. The observations of the Orion cloud suggest that subclustering occurs across large regions of the cloud (Megeath et al. 2012) so that the formation of a cluster would inv ...
Star formation and the interstellar medium in galaxy
... has been developed by Mihos & Hernquist (1994), in which gas particles evolve into hybrid gas/star particles and finally into stars, thus keeping the total amount of particles fixed, and yet without constraints on mass conversion from gas to stars. A drawback of their model is that the new star and ...
... has been developed by Mihos & Hernquist (1994), in which gas particles evolve into hybrid gas/star particles and finally into stars, thus keeping the total amount of particles fixed, and yet without constraints on mass conversion from gas to stars. A drawback of their model is that the new star and ...
SearchCal: a Virtual Observatory tool for searching - HAL-Insu
... the measurement of the visibility amplitudes. Equation 3 shows that the expected accuracy on the target visibility strongly depends on the accuracy of the calibrator visibility. A calibrator is a star for which the visibility is known (or can be predicted) with high accuracy. It should have physical ...
... the measurement of the visibility amplitudes. Equation 3 shows that the expected accuracy on the target visibility strongly depends on the accuracy of the calibrator visibility. A calibrator is a star for which the visibility is known (or can be predicted) with high accuracy. It should have physical ...
radial metallicity gradients and age-metallicity relation of stars in the
... build-up of radial and vertical abundance distributions in the Galactic disk, we need tracers of stellar populations of all ages, from the earliest epoch of Galaxy formation to the present day. With the data taken with the Gaia-ESO Survey, which form the basis of our work, we are in a good position ...
... build-up of radial and vertical abundance distributions in the Galactic disk, we need tracers of stellar populations of all ages, from the earliest epoch of Galaxy formation to the present day. With the data taken with the Gaia-ESO Survey, which form the basis of our work, we are in a good position ...
Analysis of white dwarfs with strange-matter cores
... binary. The mass of the field white dwarf GD 140 is also well determined. It has been wellstudied spectroscopically as its temperature is very high so that this star is relatively bright. Nevertheless, both of these stars are far more compact than expected for a normal white dwarf. ...
... binary. The mass of the field white dwarf GD 140 is also well determined. It has been wellstudied spectroscopically as its temperature is very high so that this star is relatively bright. Nevertheless, both of these stars are far more compact than expected for a normal white dwarf. ...
A massive hypergiant star as the progenitor of the supernova SN
... thus bolster previous suggestions3,18–20 that at least some massive hypergiant stars explode during, or shortly after, a violent LBV-like eruption phase, as hydrogen-rich supernovae in which the ejecta interact almost immediately with the slowly moving shells from prior eruptions. The lack of an ext ...
... thus bolster previous suggestions3,18–20 that at least some massive hypergiant stars explode during, or shortly after, a violent LBV-like eruption phase, as hydrogen-rich supernovae in which the ejecta interact almost immediately with the slowly moving shells from prior eruptions. The lack of an ext ...
Visible neutral helium lines in main sequence B-type stars
... 5. Effects of the microturbulence There is a considerable spread in the observed EW’s especially for Teff > 20000 K and, in certain cases, this is larger than accountable by the range of log g assumed in our calculations. We suggest that this is partly due to our poor understanding of microturbulenc ...
... 5. Effects of the microturbulence There is a considerable spread in the observed EW’s especially for Teff > 20000 K and, in certain cases, this is larger than accountable by the range of log g assumed in our calculations. We suggest that this is partly due to our poor understanding of microturbulenc ...
Max Planck Institute for Gravitational Physics
... - IDEAs: (1) there should be another relaxation mechanism (not twobody) efficient on DYNAMICAL timescale (crossing time) (2) by 2nd law of thermodynamics: such mechanism must ...
... - IDEAs: (1) there should be another relaxation mechanism (not twobody) efficient on DYNAMICAL timescale (crossing time) (2) by 2nd law of thermodynamics: such mechanism must ...
PLANETS AND INFRARED EXCESSES: PRELIMINARY RESULTS
... 100 AU, analogous to the zodiacal cloud and the Kuiper Belt in our own solar system. Because of effects such as radiation pressure and Poynting-Robertson drag, the lifetime of the dust is generally much shorter than the age of the system; any dust observed must have been recently produced. In the so ...
... 100 AU, analogous to the zodiacal cloud and the Kuiper Belt in our own solar system. Because of effects such as radiation pressure and Poynting-Robertson drag, the lifetime of the dust is generally much shorter than the age of the system; any dust observed must have been recently produced. In the so ...
The age structure of the Milky Way`s halo
... at the Galactic center (Z is the vertical distance above or below the Galactic plane), where the squares in panel d represent the mean colours (and ages) of the BHB stars in a grid of 1 kpc square pixels. Panels a, b, and c of Fig. 1 are constructed by applying a Gaussian kernel smooth (of width 3 k ...
... at the Galactic center (Z is the vertical distance above or below the Galactic plane), where the squares in panel d represent the mean colours (and ages) of the BHB stars in a grid of 1 kpc square pixels. Panels a, b, and c of Fig. 1 are constructed by applying a Gaussian kernel smooth (of width 3 k ...
Can Extra Mixing in RGB and AGB Stars Be Attributed to Magnetic
... spherical symmetry, so radiative and hydrostatic equilbria cannot be maintained simultaneously. This conflict drives meridional circulations known as the Eddington-Sweet effect (Eddington 1925; Sweet 1950). Meridional circulation in a radiatively stratified star implies a transport of angular moment ...
... spherical symmetry, so radiative and hydrostatic equilbria cannot be maintained simultaneously. This conflict drives meridional circulations known as the Eddington-Sweet effect (Eddington 1925; Sweet 1950). Meridional circulation in a radiatively stratified star implies a transport of angular moment ...
110 - Institute for Astronomy
... using time-dependent numerical MHD simulations, how such spurs could form (and subsequently fragment) from the interaction of a gaseous interstellar medium with a stellar spiral arm. We model the gaseous medium as a selfgravitating, magnetized, differentially-rotating, razor-thin disk. The basic flo ...
... using time-dependent numerical MHD simulations, how such spurs could form (and subsequently fragment) from the interaction of a gaseous interstellar medium with a stellar spiral arm. We model the gaseous medium as a selfgravitating, magnetized, differentially-rotating, razor-thin disk. The basic flo ...
PDF file
... contrast to their high mass counterparts, low-mass stars offer distinct advantages to address the aforementioned issues. They are simply vastly more numerous than O, B, and A stars, allowing statistical studies not possible with the few massive stars in each region. Their spatial distribution is a f ...
... contrast to their high mass counterparts, low-mass stars offer distinct advantages to address the aforementioned issues. They are simply vastly more numerous than O, B, and A stars, allowing statistical studies not possible with the few massive stars in each region. Their spatial distribution is a f ...
fundamental properties of kepler planet- candidate
... (Vandakurov 1968; Tassoul 1980; Gough 1986). The large frequency separation Δν is the spacing between modes with the same spherical degree l and consecutive radial order n, and probes the sound travel time across the stellar diameter. This means that Δν is related to the mean stellar density and is ...
... (Vandakurov 1968; Tassoul 1980; Gough 1986). The large frequency separation Δν is the spacing between modes with the same spherical degree l and consecutive radial order n, and probes the sound travel time across the stellar diameter. This means that Δν is related to the mean stellar density and is ...