847 research outputs found
Gender Bending and Bending Gender (Re)Creating Aesthetic Realities of Organization Practices
The following paper incorporates various writing genres including fiction, narrative, and scholarly discourse to demonstrate the potential importance of aesthetic theory for transforming gendered organizational practices. It starts off with Kelly‘s, a student of organizational communication, ―final exam‖ essay, which explores the gendered politics of promotion. Her professor‘s response explores the gendered politics of ―doing feminism.‖ Taken individually, Kelly and Dr. McGuire (re)create an aesthetic reality of traditional, essentializing organizational practices. Taken together, they (re)create aesthetic meanings that pose formidable challenges and potential transformations for the way we ―do gender‖ organizationally. In the end, this paper or ―petite narrative‖ stands as an aesthetic challenge towards transforming the way we ―do (feminist organization) scholarship‖ organizationally
The Detonation Mechanism of the Pulsationally-Assisted Gravitationally-Confined Detonation Model of Type Ia Supernovae
We describe the detonation mechanism comprising the "Pulsationally Assisted"
Gravitationally Confined Detonation (GCD) model of Type Ia supernovae SNe Ia.
This model is analogous to the previous GCD model reported in Jordan et
al.(2008); however, the chosen initial conditions produce a substantively
different detonation mechanism, resulting from a larger energy release during
the deflagration phase. The resulting final kinetic energy and nickel-56 yields
conform better to observational values than is the case for the "classical" GCD
models. In the present class of models, the ignition of a deflagration phase
leads to a rising, burning plume of ash. The ash breaks out of the surface of
the white dwarf, flows laterally around the star, and converges on the
collision region at the antipodal point from where it broke out. The amount of
energy released during the deflagration phase is enough to cause the star to
rapidly expand, so that when the ash reaches the antipodal point, the surface
density is too low to initiate a detonation. Instead, as the ash flows into the
collision region (while mixing with surface fuel), the star reaches its
maximally expanded state and then contracts. The stellar contraction acts to
increase the density of the star, including the density in the collision
region. This both raises the temperature and density of the fuel-ash mixture in
the collision region and ultimately leads to thermodynamic conditions that are
necessary for the Zel'dovich gradient mechanism to produce a detonation. We
demonstrate feasibility of this scenario with three 3-dimensional (3D), full
star simulations of this model using the FLASH code. We characterized the
simulations by the energy released during the deflagration phase, which ranged
from 38% to 78% of the white dwarf's binding energy. We show that the necessary
conditions for detonation are achieved in all three of the models.Comment: 22 pages, 8 figures; Ap
On variations of the brightness of type Ia supernovae with the age of the host stellar population
Recent observational studies of type Ia supernovae (SNeIa) suggest
correlations between the peak brightness of an event and the age of the
progenitor stellar population. This trend likely follows from properties of the
progenitor white dwarf (WD), such as central density, that follow from
properties of the host stellar population. We present a statistically
well-controlled, systematic study utilizing a suite of multi-dimensional SNeIa
simulations investigating the influence of central density of the progenitor WD
on the production of Fe-group material, particularly radioactive Ni-56, which
powers the light curve. We find that on average, as the progenitor's central
density increases, production of Fe-group material does not change but
production of Ni-56 decreases. We attribute this result to a higher rate of
neutronization at higher density. The central density of the progenitor is
determined by the mass of the WD and the cooling time prior to the onset of
mass transfer from the companion, as well as the subsequent accretion heating
and neutrino losses. The dependence of this density on cooling time, combined
with the result of our central density study, offers an explanation for the
observed age-luminosity correlation: a longer cooling time raises the central
density at ignition thereby producing less Ni-56 and thus a dimmer event. While
our ensemble of results demonstrates a significant trend, we find considerable
variation between realizations, indicating the necessity for averaging over an
ensemble of simulations to demonstrate a statistically significant result.Comment: 5 pages, 4 figures, 1 table, accepted to ApJ
Challenges Modeling the Low-Luminosity Type Iax Supernovae
Numerical models allow the investigation of phenomena that cannot exist in a
laboratory. Computational simulations are therefore essential for advancing our
knowledge of astrophysics, however, the very nature of simulation requires
making assumptions that can substantially affect their outcome. Here, we
present the challenges faced when simulating dim thermonuclear explosions, Type
Iax supernovae. This class of dim events produce a slow moving, sparse ejecta
that presents challenges for simulation. We investigate the limitations of the
equation of state and its applicability to the expanding, cooling ejecta. We
also discuss how the "fluff", i.e. the low-density gas on the grid in lieu of
vacuum, inhibits the ejecta as it expands. We explore how the final state of
the simulation changes as we vary the character of the burning, which
influences the outcome of the explosion. These challenges are applicable to a
wide range of astrophysical simulations, and are important to discuss and
overcome as a community.Comment: 10 pages, 7 figures, submitted to the Proceedings of 15th
International Conference on Numerical Modeling of Space Plasma Flows
(AstroNum
- …