23,158 research outputs found
Simulating the Role of Stellar Rotation in the Spectroscopic Effects of Differential Limb Magnification
Finite-source effects of gravitationally microlensed stars have been well
discussed in the literature, but the role that stellar rotation plays has been
neglected. A differential magnification map applied to a differentially
Doppler-shifted surface alters the profiles of absorption lines, compromising
their ordinarily symmetric nature. Herein, we assess the degree to which this
finite-source effect of differential limb magnification (DLM), in combination
with stellar rotation, alters spectroscopically derived stellar properties. To
achieve this, we simulated a grid of high-magnification microlensing events
using synthetic spectra. Our analysis shows that rotation of the source
generates differences in the measured equivalent widths of absorption lines
supplementary to DLM alone, but only of the order of a few percent. Using the
wings of H alpha from the same simulated data, we confirmed the result of
Johnson et al. (2010) that DLM alters measurements of effective temperature by
< 100 K for dwarf stars, while showing rotation to bear no additional effect.Comment: Accepted for publication in PASA, 7 pages, 5 figures, 1 tabl
Radiation budget measurement/model interface
This final report includes research results from the period February, 1981 through November, 1982. Two new results combine to form the final portion of this work. They are the work by Hanna (1982) and Stevens to successfully test and demonstrate a low-order spectral climate model and the work by Ciesielski et al. (1983) to combine and test the new radiation budget results from NIMBUS-7 with earlier satellite measurements. Together, the two related activities set the stage for future research on radiation budget measurement/model interfacing. Such combination of results will lead to new applications of satellite data to climate problems. The objectives of this research under the present contract are therefore satisfied. Additional research reported herein includes the compilation and documentation of the radiation budget data set a Colorado State University and the definition of climate-related experiments suggested after lengthy analysis of the satellite radiation budget experiments
F-15 inlet/engine test techniques and distortion methodologies studies. Volume 7: Cross correlation functions.
Cross correlation function plots were used to determine if peak distortion data taken from a subscale inlet model can be used to predict peak distortion levels for a full scale flight test vehicle
F-15 inlet/engine test techniques and distortion methodologies studies. Volume 3: Power spectral density plots
Power spectral density plots were used to determine if peak distortion data taken from a subscale inlet model can be used to predict peak distortion levels for a full scale flight test vehicle
F-15 inlet engine test techniques and distortion methodologies studies. Volume 9: Stability audits
Stability audit plots were used to determine if peak distortion data taken from a subscale inlet model can be used to predict peak distortion levels for a full scale flight test vehicle
F-15 inlet/engine test techniques and distortion methodologies studies. Volume 2: Time variant data quality analysis plots
Time variant data quality analysis plots were used to determine if peak distortion data taken from a subscale inlet model can be used to predict peak distortion levels for a full scale flight test vehicle
F-15 inlet/engine test techniques and distortion methodologies studies. Volume 8: Cross spectral density plots
Cross spectral density plots were used to determine if peak distortion data taken from a subscale inlet model can be used to predict peak distortion levels for a full scale flight test vehicle
F-15 inlet/engine test techniques and distortion methodologies studies. Volume 4: Autocorrelation functions
Autocorrelation function plots were used to determine if peak distortion data taken from a subscale inlet model can be used to predict peak distortion levels for a full scale flight test vehicle
A three dimensional model of the Venusian thermosphere with superrotation
An improved three dimensional spectral model of the thermosphere of Venus is described. The model solves the Navier-Stokes equations and includes nonlinear effects for an arbitrary number of atmospheric species. A two dimensional axisymmetric model of the superrotation of the thermosphere is also presented. This model addresses the Pioneer-Venus mission finding, which suggested the thermospheric rotation rate to be much higher than that of the planet as seen from the asymmetric distribution of hydrogen and helium. Both models include the effects of an anisotropic eddy diffusion that is consistent with atmospheric mixing length theory
F-15 inlet/engine test techniques and distortion methodologies studies. Volume 5: Effect of filter cutoff frequency on turbulence plots
The effect of filter cutoff frequency on turbulence plots were used to determine if peak distortion data taken from a subscale inlet model can be used to predict peak distortion levels for a full scale flight test vehicle
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