Bulletin of the American Physical Society
2011 Annual Meeting of the Four Corners Section of the APS
Volume 56, Number 11
Friday–Saturday, October 21–22, 2011; Tuscon, Arizona
Session M4: Studying Physics in the Solar System |
Hide Abstracts |
Chair: Eric Greenfield, University of Arizona Room: UA Student Union Copper |
Saturday, October 22, 2011 11:10AM - 11:22AM |
M4.00001: Realistic Detectability of Close Interstellar Comets Nathaniel Cook, Darin Ragozzine, Denise Stephens From our understanding of planet formation we know that many comets are created and ejected, but we have yet to observe ``interstellar'' comets from other stars. A detailed estimation of the population of these comets has been recently determined. Those results concluded that based on their size and distribution that the LSST would be unlikely to see any interstellar comets beyond 5 AU. Our work takes into account the gravitational focusing of the Sun and the brightening of comets as they come closer to the Sun. We will more accurately describe the probability of realistically observing these close interstellar comets, using numerical simulations. We track the comets in their hyperbolic orbits about the Sun. We show that the velocity of the Sun relative to the galactic Local Standard of Rest has negligible effect on the probability of observation, while the velocity dispersion of the comets has a greater effect though still small compared to uncertainties in the population. We will present the magnitude distribution of comets, including a model for comet brightening or outgassing, and discuss the prospects for LSST in detecting an interstellar comet. [Preview Abstract] |
Saturday, October 22, 2011 11:22AM - 11:34AM |
M4.00002: Comparing simulations of rising flux tubes through the solar convection zone with observations of active region properties: constraining the dynamo field strength Maria Weber, Yuhong Fan, Mark Miesch We use a thin flux tube model in a rotating spherical shell of turbulent convective flows to study how active region scale flux tubes rise buoyantly from the bottom of the convection zone to near the solar surface. We investigate toroidal flux tubes originating at the base of the convection zone with field strengths ranging from 15 kG to 100 kG at initial latitudes ranging from 1 degree to 40 degrees with a total flux of 10$^{20}$ Mx to 10$^{22}$ Mx. With the influence of a convective velocity field, rise times are reduced (from years to months) for all fluxes, and loops are able to emerge at low latitudes even for large flux. We examine geometric and magnetic field asymmetries between the leading and following legs of the emerging loops, and the tilt angle of the emerging flux tube as a function of the latitude in order to identify the observed Joy's Law trend of solar active regions. By comparing our flux tube simulation results with observations of solar active regions, we attempt to constrain the magnetic field generated by the solar dynamo at the base of the convection zone. [Preview Abstract] |
Saturday, October 22, 2011 11:34AM - 11:46AM |
M4.00003: Looking to the sky to predict Solar Power Intermittency Vijai Thottathil Jayadevan, Alex Cronin, Vincent Lonij, Sarah Jones, Gabe Torres Intermittency in solar power production is one of the grand challenges impeding the adoption of solar power on a Giga Watt scale. Intermittency due to clouds will lead to mismatches between power production and consumption which can affect grid power quality and cause blackouts. We have installed a camera at the Tucson Electric Solar Power Test Yard which continuously tracks the sun from dawn to dusk. By analyzing images that the camera provides, we are developing an algorithm which can predict solar irradiance and cloud motion. These predictions can then be incorporated in a solar-aware smart-grid (using load management and energy storage) to reduce production/consumption mismatch due to solar intermittency. [Preview Abstract] |
Saturday, October 22, 2011 11:46AM - 11:58AM |
M4.00004: Negligible Kinetic Helicity Can Drive Large Scale Dynamos Jonathan Pietarila Graham, Eric Blackman, Pablo Mininni, Annick Pouquet Turbulent helical velocities drive large scale magnetic field growth and steepen the small scale magnetic energy spectrum, but the minimum sufficient fractional kinetic helicity $f_{h,C}$ to do so has not been previously quantified. Using direct numerical simulations, we show that $f_{h,C}$ strongly decreases as the ratio of forcing to large scale wavenumbers $k_F/k_{min}$ increases. We also develop a simple theory that explains the simulation results. {For $k_F/k_{min}\ge6$ we find $f_{h,C}\la 5\%$, and our theory predicts that, in the asymptotic limit $k_F/k_{min}\rightarrow\infty$, $f_{h,C}\sim(k_F/k_{min})^{-5}$,} implying that very small helicity fractions strongly influence magnetic spectra for {even moderate} scale separation. [Preview Abstract] |
Saturday, October 22, 2011 11:58AM - 12:10PM |
M4.00005: Low Thrust Orbital Maneuvers Using Ion Propulsion Eric Ramesh Low-thrust maneuver options, such as electric propulsion, offer specific challenges within mission-level Modeling, Simulation, and Analysis (MS{\&}A) tools. This project seeks to transition techniques for simulating low-thrust maneuvers from detailed engineering level simulations such as AGI's Satellite ToolKit (STK) Astrogator to mission level simulations such as the System Effectiveness Analysis Simulation (SEAS). Our project goals are as follows: A) Assess different low-thrust options to achieve various orbital changes; B) Compare such approaches to more conventional, high-thrust profiles; C) Compare computational cost and accuracy of various approaches to calculate and simulate low-thrust maneuvers; D) Recommend methods for implementing low-thrust maneuvers in high-level mission simulations; E) prototype recommended solutions. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700