Astrophysics and Astronomy Commons^™

Prospects For Sme Tests With Experiments At Syrte And Lkb, C. Guerlin, H. Pihan-Le Bars, Q. G. Bailey, P. Wolf

Publications

Preliminary work has been done in order to assess the perspectives of metrology and fundamental physics atomic experiments at SYRTE and LKB in the search for physics beyond the Standard Model and General Relativity. The first studies we identified are currently ongoing with the Microscope mission and with a Cs fountain clock. The latter brings significant improvement on the proton-sector coefficient cTT down to the 10−17 GeV level.

Gravity Sector Of The Sme, Q. G. Bailey

Publications

In this talk, the gravity sector of the effective field theory description of local Lorentz violation is discussed, including minimal and nonminimal curvature couplings. Also, recent experimental and observational analyses including solar-system ephemeris and short-range gravity tests are reviewed.

The Dawn–Dusk Asymmetry Of Ion Density In The Dayside Magnetosheath And Its Annual Variability Measured By Themis, Andrew P. Dimmock, Tuija I. Pulkkinen, Adnane Osmane, Katariina Nykyri

Publications

The local and global plasma properties in the magnetosheath play a fundamental role in regulating solar wind–magnetosphere coupling processes. However, the magnetosheath is a complex region to characterise as it has been shown theoretically, observationally and through simulations that plasma properties are inhomogeneous, non-isotropic and asymmetric about the Sun-Earth line. To complicate matters, dawn–dusk asymmetries are sensitive to various changes in the upstream conditions on an array of timescales. The present paper focuses exclusively on dawn–dusk asymmetries, in particularly that of ion density. We present a statistical study using THEMIS data of the dawn–dusk asymmetry of ion density in the …

Optical Tracking And Spectral Characterization Of Cubesats For Operational Missions, Forrest Gasdia

Doctoral Dissertations and Master's Theses

Orbital debris in low Earth orbit is of growing concern to operational satellites from the government and commercial sector. With an uptick in worldwide satellite launches and the growing adoption of the CubeSat standard, the number of small objects in orbit are increasing at a faster pace than ever. As a result, a cascading collision event seems inevitable in the near future.

The United States Strategic Command tracks and determines the orbit of resident space objects using a worldwide network of radar and optical sensors. However, in order to better protect space assets, there has been increased interest in not …

Book Review: Moons Of The Solar System: From Giant Ganymede To Dainty Dactyl, T. D. Oswalt

Publications

This document is Dr. Oswalt’s review of Moons of the Solar System : from Giant Ganymede to Dainty Dactyl by James A. Hall, III. Springer 2015. 297p index afp, 9783319206356 $34.99, 9783319206363 $19.99

Observation Of Gravitational Waves From A Binary Black Hole Merger, B. P. Abbott, K. Gill, B. Hughey, M, J. Szczepańczyk, M. Zanolin, Et Al.

Publications

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10−21. It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203 000 years, equivalent to a significance greater …

Human Behavior During Spaceflight - Evidence From An Analog Environment, Kenny M. Arnaldi, Guy Smith, Jennifer E. Thropp

Journal of Aviation/Aerospace Education & Research

Spaceflight offers a multitude of stressors to humans living and working in space, originating from the external space environment and the life-support system. Future space participants may be ordinary people with different medical and psychosocial backgrounds who may not receive the intense spaceflight preparation of astronauts. Consequently, during a mission, a space participant’s mood and behavior could differ from a trained astronaut. This study was an exploratory research project that used an artificial habitat to replicate an orbital environment and the activities performed by humans in space. The study evaluated whether the type of environment affects mood and temperament. Two …

Gravitons To Photons--Attenuation Of Gravitational Waves, Preston Jones, Douglas Singleton

Publications

In this essay, we examine the response of an Unruh–DeWitt (UD) detector (a quantum two-level system) to a gravitational wave background. The spectrum of the UD detector is of the same form as some scattering processes or three body decays such as muon-electron scattering or muon decay. Based on this similarity, we propose that the UD detector response implies a “decay” or attenuation of gravitons, G, into photons, γ, via G+G→γ+γ or G→γ+γ+G. Over large distances such a decay/attenuation may have consequences in regard to the detection of gravitational waves.

The Impact Of Solar Wind Ulf Bz Fluctuations On Geomagnetic Activity For Viscous Timescales During Strongly Northward And Southward Imf, A. Osmane, A. P. Dimmock, R. Naderpour, T. I. Pulkkinen, K. Nykyri

Publications

We analyze more than 17 years of OMNI data to statistically quantify the impact of IMF Bz fluctuations on AL by using higher-order moments in the AL-distribution as a proxy. For strongly southward interplanetary magnetic field (IMF), the AL distribution function is characterized by a decrease of the skewness, a shift of its peak from −30 nT to −200 nT, and a broadening of the distribution core. During northward IMF, the distribution of AL is characterized by a significant reduction of the standard deviation and weight in the tail. Following this characterization of AL for southward and northward IMF, we …

Testing Lorentz Symmetry With Planetary Orbital Dynamics, A. Hees, Q. G. Bailey, C. Le Poncin-Lafitte, A. Bourgoin, A. Rivoldini, B. Lamine, F. Meynadier, C. Guerlin, P. Wolf

Publications

Planetary ephemerides are a very powerful tool to constrain deviations from the theory of general relativity (GR) using orbital dynamics. The effective field theory framework called the Standard-Model Extension (SME) has been developed in order to systematically parametrize hypothetical violations of Lorentz symmetry (in the Standard Model and in the gravitational sector). In this communication, we use the latest determinations of the supplementary advances of the perihelia and of the nodes obtained by planetary ephemerides analysis to constrain SME coefficients from the pure gravity sector and also from gravity-matter couplings. Our results do not show any deviation from GR and …

Impact Of Declining Proposal Success Rates On Scientific Productivity, Ted Von Hippel, Priscilla Cushman, Todd Hoeksema, Chryssa Kouveliotou, James Lowenthal, Bradley Peterson, Keivan G. Stassun,

Publications

Over the last decade proposal success rates in the fundamental sciences have dropped significantly. Astronomy and related fields funded by NASA and NSF are no exception. Data across agencies show that this is not principally the result of a decline in proposal merit (the proportion of proposals receiving high rankings is largely unchanged), nor of a shift in proposer demographics (seniority, gender, and institutional affiliation have all remained unchanged), nor of an increase (beyond inflation) in the average requested funding per proposal, nor of an increase in the number of proposals per investigator in any one year. Rather, the statistics …

The Lunar Exosphere: Spatial And Temporal Variations Of Sodium And Potassium Emissions From November 2013 To May 2014, Dona Chathuni P. Kuruppuaratchi

Doctoral Dissertations and Master's Theses

I apply high resolution spectroscopy to investigate the lunar exosphere by measuring sodium and potassium spectral line profiles to determine spatial and temporal variations in exospheric effective temperatures and velocities. Observations were made from the National Solar Observatory (MMP) at Kitt Peak, Arizona from November 2013 to May 2014, with the exception of March 2014. Data collection was centered of full moon and spanned several nights with lunar phase angle coverage ranging from 65.6° (waxing) to 78.7° (waning). Observations were concurrent with the NASA LADEE mission science and instrument testing phases. We used a dial etalon Fabry-Perot spectrometer with a …

Solar Wind Energy Input To The Magnetosheath And At The Magnetopause, T. I. Pulkkinen, A. P. Dimmock, A. Osmane, K. Nykyri

Publications

Using Time History of Events and Macroscale Interactions During Substorms observations, we show that the efficiency of the energy entry through the magnetopause as measured by the Poynting vector normal component depends on the combination of the solar wind speed and the southward component of the interplanetary magnetic field (IMF): Most efficient energy transfer occurs when the IMF BZ is only moderately negative, and the solar wind speed is high. This means that for the same level of solar wind driver parameters (electric field, epsilon, or other), different combinations of V and BZ will produce different driving at the magnetopause. …

Magnetic Flux Circulation In The Rotationally Driven Giant Magnetospheres, P. A. Delamere, A. Otto, X. Ma, F. Bagenal, R. J. Wilson

Publications

The giant‐planet magnetodiscs are shaped by the radial transport of plasma originating in the inner magnetosphere. Magnetic flux transport is a key aspect of the stretched magnetic field configuration of the magnetodisc. While net mass transport is outward (ultimately lost to the solar wind), magnetic flux conservation requires a balanced two‐way transport process. Magnetic reconnection is a critical aspect of the balanced flux transport. We present a comprehensive analysis of current sheet crossings in Saturn's magnetosphere using Cassini magnetometer data from 2004 to 2012 in an attempt to quantify the circulation of magnetic flux, emphasizing local time dependence. A key …

Book Review: The Scientific Exploration Of Venus, T. D. Oswalt

Publications

This document is Dr. Oswalt’s review of The Scientific Exploration of Venus, by Fredric W. Taylor. Cambridge, 2014 295p bibl index, 9781107023482 $48.00

A Statistical Study Of The Dawn-Dusk Asymmetry Of Ion Temperature Anistrophy And Mirror Mode Occurrence In The Terrestrial Dayside Magnetosheath Using Themis Data, A. P. Dimmock, A. Osmane, T. I. Pulkkinen, K. Nykyri

Publications

We present a statistical study of ion temperature anisotropy and mirror mode activity in the Earth's dayside magnetosheath using 6 years of Time History of Events and Macroscale Interactions during Substorms (THEMIS) observations focusing on the quantification of dawn-dusk asymmetry as a function of upstream conditions and distance from the magnetopause. Our statistical data show a pronounced dusk favored asymmetry of T⊥/T∥ which drives a similar asymmetry of mirror mode activity. T⊥/T∥ decreases with increasing solar wind Alfvén Mach number, whereas mirror mode occurrence increases. In both cases, the relative asymmetry between the dawn and dusk flanks decrease with increasing …

Core-Collapse Supernovae Overview With Swift Collaboration, Kiranjyot Gill, Michele Zanolin, Marek Szczepańczyk

Publications

The Core-Collapse supernovae (CCSNe) mark the dynamic and explosive end of the lives of massive stars. The mysterious mechanism, primarily focused with the shock revival phase, behind CCSNe explosions could be explained by detecting the corresponding gravitational wave (GW) emissions by the laser interferometer gravitational wave observatory, LIGO. GWs are extremely hard to detect because they are weak signals in a floor of instrument noise. Optical observations of CCSNe are already used in coincidence with LIGO data, as a hint of the times where to search for the emission of GWs. More of these hints would be very helpful. For …

A Statistical Study Into The Spatial Distribution And Dawn-Dusk Asymmetry Of Dayside Magnetosheath Ion Temperatures As A Function Of Upstream Solar Wind Conditions, A. P. Dimmock, K. Nykyri, H. Karimabadi, A. Osmane, T. I. Pulkkinen

Publications

The magnetosheath contains the shocked solar wind and behaves as a natural filter to the solar wind plasma before it reaches the magnetosphere. The redistribution of kinetic energy at the bow shock results in significant thermalization of the solar wind plasma, resulting in a magnetosheath temperature profile which is highly nonhomogeneous and nonisotropic and differs between the dawn and dusk flanks. The present study attempts to study the spatial distribution of magnetosheath ion temperature as a function of upstream solar wind conditions. We pay particular attention to the dawn/dusk asymmetry in which we attempt to quantify using experimental data collected …

Asymmetric Kelvin-Helmholtz Propagation At Saturn's Dayside Magnetopause, X. Ma, B. Stauffer, P. A. Delamere, A. Otto

Publications

At Saturn's magnetopause, the shear flows are maximized (minimized) in the prenoon (postnoon) sector due to the rapid planetary rotation and the corotating magnetodisc. As such, the prenoon sector is expected to be more Kelvin‐Helmholtz (KH) unstable than the postnoon sector; however, in situ Cassini data analyses showed that the evidence of KH activity favors the postnoon sector. In this study, we use a two‐dimensional MHD simulation to demonstrate that fast‐growing KH modes strongly deform and diffuse the boundary layer on a time scale of a few minutes in the prenoon sector. Therefore, the KH observational signature is difficult to …

To Apply Or Not To Apply: A Survey Analysis Of Grant Writing Costs And Benefits, Ted Von Hippel, Courtney Von Hippel

Publications

We surveyed 113 astronomers and 82 psychologists active in applying for federally funded research on their grant-­‐writing history between January, 2009 and November, 2012. We collected demographic data, effort levels, success rates, and perceived non-­‐financial benefits from writing grant proposals. We find that the average proposal takes 116 PI hours and 55 CI hours to write; although time spent writing was not related to whether the grant was funded. Effort did translate into success, however, as academics who wrote more grants received more funding. Participants indicated modest non-­‐monetary benefits from grant writing, with psychologists reporting a somewhat greater benefit overall …

What Do We Know About Lorentz Symmetry?, Q. G. Bailey

Publications

Precision tests of Lorentz symmetry have become increasingly of interest to the broader gravitational and high-energy physics communities. In this talk, recent work on violations of local Lorentz invariance in gravity is discussed, including recent analysis constraining Lorentz violation in a variety of gravitational tests. The arena of short-range tests of gravity is highlighted, demonstrating that such tests are sensitive to a broad class of unexplored signals that depend on sidereal time and the geometry of the experiment.

Bayesian Investigation Of Isochrone Consistency Using The Old Open Cluster Ngc 188, Shane Hills, Ted Von Hippel, Stéphane Courteau, Aaron M. Geller

Publications

This paper provides a detailed comparison of the differences in parameters derived for a star cluster from its color– magnitude diagrams (CMDs) depending on the filters and models used. We examine the consistency and reliability of fitting three widely used stellar evolution models to 15 combinations of optical and near-IR photometry for the old open cluster NGC 188. The optical filter response curves match those of theoretical systems and are thus not the source of fit inconsistencies. NGC 188 is ideally suited to this study thanks to a wide variety of high-quality photometry and available proper motions and radial velocities …

Short-Range Gravity And Lorentz Violation, Quentin G. Bailey, V. Alan Kostelecký, Rui Xu

Publications

Comparatively few searches have been performed for violations of local Lorentz invariance in the pure-gravity sector. We show that tests of short-range gravity are sensitive to a broad class of unconstrained and novel signals that depend on the experimental geometry and on sidereal time.

Quantum Tests Of The Einstein Equivalence Principle With The Ste-Quest Space Mission, Brett Altschul, Quentin G. Bailey, Luc Blanchet, Kai Bongs, Philippe Bouyer, Luigi Cacciapuoti, Et Al.

Publications

We present in detail the scientific objectives in fundamental physics of the Space–Time Explorer and QUantum Equivalence Space Test (STE–QUEST) space mission. STE–QUEST was pre-selected by the European Space Agency together with four other missions for the cosmic vision M3 launch opportunity planned around 2024. It carries out tests of different aspects of the Einstein Equivalence Principle using atomic clocks, matter wave interferometry and long distance time/frequency links, providing fascinating science at the interface between quantum mechanics and gravitation that cannot be achieved, at that level of precision, in ground experiments. We especially emphasize the specific strong interest of performing …

Exploring How Social Media Can Be Used To Promote Space Awareness: A Case Study Of The Yuri's Night Web 2.0, Alan Steinberg, Jeffrey Alles, Ryan L. Kobrick

Publications

Despite the importance of social media as an inexpensive and efficient means of communication, it is not clear to what degree space advocacy groups are making a strong organized effort to use the resources available to them. Moreover, there is no previous literature that specifically examines the use of social media tools by space organizations. This study seeks to start a larger dialog regarding how the space advocacy community can make use of these tools to promote their mission. Using a case study approach, this article focuses specifically on the organization of Yuri’s Night to explore how this group is …

A Deep Proper Motion Catalog Within The Sloan Digital Sky Survey Footprint, Jeffrey A. Munn, Hugh C. Harris, Ted Von Hippel, Mukremin Kilic, James W. Liebert, Kurtis A. Williams, Steven Degenarro, Elizabeth Jeffery, Trudy M. Tilleman

Publications

A new proper motion catalog is presented, combining the Sloan Digital Sky Survey (SDSS) with second epoch observations in the r band within a portion of the SDSS imaging footprint. The new observations were obtained with the 90prime camera on the Steward Observatory Bok 90 inch telescope, and the Array Camera on the U.S. Naval Observatory, Flagstaff Station, 1.3 m telescope. The catalog covers 1098 square degrees to r = 22.0, an additional 1521 square degrees to r = 20.9, plus a further 488 square degrees of lesser quality data. Statistical errors in the proper motions range from 5 mas …

The Power Of Principled Bayesian Methods In The Study Of Stellar Evolution, Ted Von Hippel, David Van Dyk, David Stenning, Elliot Robinson, Elizabeth Jeffery, Nathan Stein, William Jefferys, Erin M. O'Malley

Publications

It takes years of effort employing the best telescopes and in- struments to obtain high-quality stellar photometry, astrometry, and spectroscopy. Stellar evolution models contain the experience of life- times of theoretical calculations and testing. Yet most astronomers fit these valuable models to these precious datasets by eye. We show that a principled Bayesian approach to fitting models to stellar data yields substantially more information over a range of stellar astrophysics. We highlight advances in determining the ages of star clusters, mass ratios of binary stars, limitations in the accuracy of stellar models, post-main-sequence mass loss, and the ages of individual …

Bayesian Analysis For Stellar Evolution With Nine Parameters (Base-9): User's Manual, Ted Von Hippel, Elliot Robinson, Elizabeth Jeffery, Rachel Wagner-Kaiser, Steven Degennaro, Nathan Stein, David Stenning, William H. Jefferys, David Van Dyk

Publications

BASE-9 is a Bayesian software suite that recovers star cluster and stellar parameters from photometry. BASE-9 is useful for analyzing single-age, single-metallicity star clusters, binaries, or single stars, and for simulating such systems. BASE-9 uses Markov chain Monte Carlo and brute-force numerical integration techniques to estimate the posterior probability distributions for the age, metallicity, helium abundance, distance modulus, and line-of-sight absorption for a cluster, and the mass, binary mass ratio, and cluster membership probability for every stellar object. BASE-9 is provided as open source code on a version-controlled web server. The executables are also available as Amazon Elastic Compute Cloud …

Book Review: Planetary Rings: A Post-Equinox View 2nd Ed, T. D. Oswalt

Publications

This document is Dr. Oswalt’s review of Planetary Rings : a Post-Equinox View 2nd Ed. by Larry W. Esposito, Cambridge, 2014 246p bibl index, 9781107028821 $120.00

The Geocoronal H Α Cascade Component Determined From Geocoronal H Β Intensity Measurements, F. L. Roesler, E. J. Mierkiewicz, S. M. Nossal

Publications

"Geocoronal H α and H β intensity measurements using the Wisconsin H α Mapper Fabry-Perot are used to determine the intensity of the H α cascade component. From basic atomic physics and the work of Meier (1995), we show that the total cascade in geocoronal H α emission is 0.52 ± 0.03 times the geocoronal H β intensity, I(H β), for solar Lyman series excitation of geocoronal hydrogen. The results are consistent with the H α cascade measurements of Mierkiewicz et al. (2012), which were determined directly from the analysis of H α line profile measurements, and significantly narrow the …