Physical Sciences and Mathematics Commons^™

The Hanle Effect As A Diagnostic Of Magnetic Fields In Stellar Envelopes. V. Thin Lines From Keplerian Disks., R. Ignace

Richard Ignace

This paper focuses on the polarized profiles of resonance scattering lines that form in magnetized disks. Optically thin lines from Keplerian planar disks are considered. Model line profiles are calculated for simple field topologies of axial fields (i.e., vertical to the disk plane) and toroidal fields (i.e., purely azimuthal). A scheme for discerning field strengths and geometries in disks is developed based on Stokes Q − U diagrams for the run of polarization across line profiles that are Doppler-broadened by the disk rotation. A discussion of the Hanle effect for magnetized disks in which the magnetorotational instability (MRI) is operating …

Source Attribution Of Ozone In Southeast Texas Before And After The Deepwater Horizon Accident Using Satellite, Sonde, Surface Monitor, And Air Mass Trajectory Data, Gary A. Morris, Barry Lefer, Bernhard Rappenglueck, Christine Haman, Marc Taylor, Mark R. Schoeberl

Gary A. Morris

Since the summer of 2004, over 300 ozonesondes have been launched from Rice University (29.7 N, 95.4 W) or the University of Houston (29.7 N, 95.3 W), each < 5 km from downtown Houston. The Texas Commission on Environmental Quality maintains a large database of hourly surface ozone observations in Southeast Texas. In this study, we identify the contributions to surface ozone pollution levels from natural and anthropogenic sources, both local and remote in nature. This source identification is performed two ways: 1) through an analysis of sonde data, including ozone concentrations, wind speed and direction, and relative humidity data, and 2) through an analysis that combines trajectory calculations with surface monitor data. We also examine regional changes in Ozone Monitoring Instrument (OMI) measurements of formaldehyde and ozone from 2004 – 2010. In particular, we compare the 2010 sonde, surface monitor, and satellite data after the Deepwater Horizon accident with data from previous years to determine the impact, if any, of the large source of hydrocarbons in the Gulf of Mexico on air quality in Southeast Texas.

A Multi-Phase Suzaku Study Of Τ Sco., R. Ignace, L. M. Oskinova, M. Jardine, J. P. Cassinelli, D. H. Cohen, J.-F. Donati, R. H. D. Townsend, A. Ud-Doula

Richard Ignace

We obtained relatively high signal-to-noise X-ray spectral data of the early massive star τ Sco (B0.2V) with the Suzaku X-ray Imaging Spectrometer (XIS) instrument. This source displays several unusual features that motivated our study: (1) redshifted absorption in UV P Cygni lines to approximately +250 km s⁻¹ suggestive of infalling gas, (2) unusually hard X-ray emission requiring hot plasma at temperatures in excess of 10 MK whereas most massive stars show relatively soft X-rays at a few MK, and (3) a complex photospheric magnetic field of open and closed field lines. In an attempt to understand the hard component …

Research Data: Who Will Share What, With Whom, When, And Why?, Christine L. Borgman

Christine L. Borgman

The deluge of scientific research data has excited the general public, as well as the scientific community, with the possibilities for better understanding of scientific problems, from climate to culture. For data to be available, researchers must be willing and able to share them. The policies of governments, funding agencies, journals, and university tenure and promotion committees also influence how, when, and whether research data are shared. Data are complex objects. Their purposes and the methods by which they are produced vary widely across scientific fields, as do the criteria for sharing them. To address these challenges, it is necessary …

Lna Based On A Low Cost (~Usd1.30) Commercial Gaas Phemt Mmic Offers Wideband (0.4~1.4 Ghz) And Room-Temperature Low Noise (~0.3 Db) Performances That Satisfy The Ska Low Cost And No-Cooling Requirement, Chin-Leong Lim

Chin-Leong Lim

Introduction: New generations of radio telescopes such as the Square Kilometre Array consist of millions of receivers scattered over a continent. The array’s quantity and geographic considerations ruled out the traditional radio astronomy LNA implementation; i.e. costly InP devices cooled by high-maintenance closed-cycle helium (He) refrigerators. Several LNA designs have been proposed to address the cost and room-temperature operation constraints but none appear a clear winner. Peltier and package-scale cooling have also been proposed as a lower cost/maintenance alternative to He cooling but when multiplied by the quantity required can still carve a significant chunk of the budget. Additionally, cooling …

Absolute Ground-State Nitrogen Atom Density In A N2/Ch4 Late Afterglow: Talif Experiments And Modelling Studies, Et. Es-Sebbar, M.-C. Gazeau, Y. Benilan, A. Jolly, C D. Pintassilgo

Dr. Et-touhami Es-sebbar

Following a first study on a late afterglow in flowing pure nitrogen post discharge, we report new two-photon absorption laser-induced fluorescence (TALIF) measurements of the absolute ground-state atomic nitrogen density N(4S) and investigate the influence of methane introduced downstream from the discharge by varying the CH4 mixing ratio from 0% up to 50%. The N (4S) maximum density is about 2.2 × 1015 cm−3 in pure N2 for a residence time of 22 ms and does not change significantly for methane mixing ratio up to ~15%, while above, a drastic decrease is observed. The influence of the residence time has …

Experimental And Theoretical Studies On Nitrogen Plasma And Methane Photolysis: Implications For Laboratory Simulations Of Titan’S Atmosphere, M-C. Gazeau, Y. Benilan, E. Arzoumanian, Et. Es-Sebbar, A. Jolly

Dr. Et-touhami Es-sebbar

No abstract provided.

Spectroscopic Studies Applied To Uvis Observations Of Titan, Y. Benilan, F. Capalbo, Et. Es-Sebbar, N. Fray, A. Jolly, M-C. Gazeau, J-C. Guillemin, M. Schwell

Dr. Et-touhami Es-sebbar

No abstract provided.

Talif Investigation And Modelling Of The Absolute N(4s) Density In A N2-Ch4 Late Afterglow, C.D. Pintassilgo, Et. Es-Sebbar, Y. Benilan, M-C. Gazeau, A. Jolly

Dr. Et-touhami Es-sebbar

The purpose of the present work is the experimental and numerical study of the absolute ground-state nitrogen atoms density N(4S) in the late afterglow of a pure N2 flowing microwave discharge in which different amounts of CH4 have been injected at 25 cm downstream from the nitrogen discharge. The absolute N(4S) concentrations have been measured using Two-photon Absorption Laser-Induced Fluorescence (TALIF), while a detailed kinetic model has been developed to simulate both the discharge and the post-discharge regions. Theoretical predictions are then compared to experimental measurements.

Combined Experimental And Theoretical Studies On Methane Photolysis At 121.6 Nm And 248 Nm- Implications On A Program Of Laboratory Simulations Of Titan’S Atmosphere, C. Romanzin, E. Arzoumanian, Et. Es-Sebbar, A. Jolly, S. Perrier, M.-C. Gazeau, Y. Bénilan

Dr. Et-touhami Es-sebbar

Methane is, together with N2, the main precursor of Titan’s atmospheric chemistry. In our laboratory, we are currently developing a program of laboratory simulations of Titan’s atmosphere, where methane is intended to be dissociated by multiphotonic photolysis at 248 nm. A preliminary study has shown that multiphotonic absorption of methane at 248 nm is efficient and leads to the production of hydrocarbons such as C2H2 (Romanzin et al., 2008). Yet, at this wavelength, little is known about the branching ratios of the hydrocarbon radicals (CH3, CH2 and CH) and their following photochemistry. This paper thus aims at investigating methane photochemistry …

Deep 1.1 Mm-Wavelength Imaging Of The Goods-S Field By Aztec/Aste – I. Source Catalogue And Number Counts, Thushara Perera, K. Scott, M. Yun, G. Wilson, J. Austermann, E. Aguilar, I. Aretxaga, H. Ezawa, D. Ferrusca, B. Hatsukade, D. Hughes, D. Iono, M. Giavalisco, R. Kawabe, K. Khono, P. Mauskopf, T. Oshima, J. Rand, Y. Tamura, T. Tosaki, M. Velazquez, C. Williams, M. Zeballos

Thushara A. Perera

No abstract provided.

Application Of Asymptotic Expansions For Maximum Likelihood Estimators Errors To Gravitational Waves From Binary Mergers: The Single Interferometer Case, M. Zanolin, S. Vitale, N. Makris

Michele Zanolin

Temperature-Dependent Photoabsorption Cross-Section Of Cyano-Diacetylene In The Vacuum Uv, N. Fray, Y. Bénilan, M.-C. Gazeau, A. Jolly, M. Schwell, E. Arzoumanian, Et. Es-Sebbar, T. Ferradaz, J.- C. Guillemin

Dr. Et-touhami Es-sebbar

Using synchrotron radiation as a tunable VUV light source, we have measured, for the first time, the absolute photoabsorption cross sections of HC5N with a spectral resolution of 0.05 nm in the region between 80 and 205 nm from 233 to 298 K. The measured cross sections are used to predict the HC5N photodestruction rate in the solar system and to model a transmission spectrum in Titan's atmosphere. Comparing the latter with that acquired by the Ultraviolet Imaging Spectrograph on board the Cassini spacecraft, we have determined an upper limit of 2.7 × 10−5 on the HC5N abundance at 1100 …

The Data Conservancy: Science-Driven Information Science, Christine L. Borgman, Carole L. Palmer

Christine L. Borgman

The Data Conservancy –which is a National Science Foundation funded Datanet project with a diverse array of partners – embraces a shared vision: data curation is not an end, but rather a means to collect, organize, validate, and preserve data to address grand research challenges that face society. Key to the data conservancy approach is information science research on the data practices of the science domains. Three teams are conducting social studies of individual science domains. Prof. Carole Palmer of the University of Illinois will report on their comparative studies of multiple biosciences domains. Prof. Christine Borgman of the University …

Co And H3 + Toward Mwc 1080, Mwc 349, And Lkhα 101, Erika Gibb, S. D. Brittain, T W. Rettig, M Troutman, Theodore Simon, C Kulesa

Erika Gibb

Hard X-Ray Emission From The Massive Star-Forming Region On 2: Discovery With Xmm-Newton., L. M. Oskinova, R. A. Gruendl, R. Ignace, Y.-H. Chu, W.-R. Hamann, A. Feldmeier

Richard Ignace

We obtained X-ray XMM-Newton observations of the open cluster Berkeley 87 and the massive star-forming region (SFR) ON 2. In addition, archival infrared Spitzer Space Telescope observations were used to study the morphology of ON 2, to uncover young stellar objects, and to investigate their relationship with the X-ray sources. It is likely that the SFR ON 2 and Berkeley 87 are at the same distance, 1.23 kpc, and hence are associated. The XMM-Newton observations detected X-rays from massive stars in Berkeley 87 as well as diffuse emission from the SFR ON 2. The two patches of diffuse X-ray emission …

Radio Emission From Substellar Companions Of Evolved Cool Stars., Richard Ignace, Mark L. Giroux, Donald G. Luttermoser

Richard Ignace

A number of substellar companions to evolved cool stars have now been reported. Cool giants are distinct from their progenitor main-sequence low-mass stars in a number of ways. First, the mass loss rates of cool giant stars are orders of magnitude greater than for the late-type main-sequence stars. Secondly, on the cool side of the Linsky–Haisch ‘dividing line’, K and M giant stars are not X-ray sources, although they do show evidence for chromospheres. As a result, cool star winds are largely neutral for those spectral types, suggesting that planetary or brown dwarf magnetospheres will not be effective in standing …

Radio Emission From Substellar Companions Of Evolved Cool Stars., Richard Ignace, Mark L. Giroux, Donald G. Luttermoser

Donald G. Luttermoser

A number of substellar companions to evolved cool stars have now been reported. Cool giants are distinct from their progenitor main-sequence low-mass stars in a number of ways. First, the mass loss rates of cool giant stars are orders of magnitude greater than for the late-type main-sequence stars. Secondly, on the cool side of the Linsky–Haisch ‘dividing line’, K and M giant stars are not X-ray sources, although they do show evidence for chromospheres. As a result, cool star winds are largely neutral for those spectral types, suggesting that planetary or brown dwarf magnetospheres will not be effective in standing …

Relations Relevant To The One Body Reduction Of The Gravitational Two Body Problem, Eric Addison

Eric Addison

The one body reduction of the two body problem is outlined along with several important relations. It is verified that both masses in a binary system orbit around the common center of mass.

Instantaneous Velocities Of A Two Body Orbit, Eric Addison

Eric Addison

This short note will derive expressions for the instantaneous velocity of the components in a two-body elliptical Keplerian orbit.

Derivation Of Initial Velocities For A Two-Body Orbit In The Barycenter Frame, Eric Addison

Eric Addison

The readily available information for two body orbits generally refers to the one dimensional, reduced mass case. Information about initial conditions in the barycenter frame is not easily found. In order to derive the initial velocities required for a two-body orbit in the barycenter frame, the momentum of the reduced mass can be used.

Origins Of The Extragalactic Background At 1mm From A Combined Analysis Of The Aztec And Mambo Data In Goods-N, Kyle Penner, Alexandra Pope, Edward L. Chapin, Thomas R. Greve, Frank Bertoldi, Mark Brodwin, Ranga-Ram Chary, Christopher J, Conselice, Kristen Coppin, Mauro Giavalisco, David H. Hughes, Rob J. Ivison, Thushara Perera, Douglas Scott, Kimberly Scott, Grant Wilson

Thushara A. Perera

We present a study of the cosmic infrared background, which is a measure of the dust obscured activity in all galaxies in the Universe. We venture to isolate the galaxies responsible for the background at 1mm; with spectroscopic and photometric redshifts we constrain the redshift distribution of these galaxies. We create a deep 1.16mm map (sigma ~ 0.5mJy) by combining the AzTEC 1.1mm and MAMBO 1.2mm datasets in GOODS-N. This combined map contains 41 secure detections, 13 of which are new. By averaging the 1.16mm flux densities of individually undetected galaxies with 24um flux densities > 25uJy, we resolve 31--45 per …

Binary Tidal Disruption Radius, Eric Addison

Eric Addison

An expression for the tidal disruption radius of a binary system is calculated.

The Zeeman Effect In The Sobolev Approximation Ii. Radial Split Monopole Fields And The ‘Heartbeat’ Stokes V Profile., K. G. Gayley, R. Ignace

Richard Ignace

We calculate the circularly polarized Stokes V(λ) profile for emission lines, formed in hot-star winds threaded with a weak radial magnetic field. For simplicity, the field is treated as a split monopole under the assumptions that it has been radially combed by the wind, and rotation is not playing a central role. Invoking the weak-field approximation, we find that the V(λ) profile has a characteristic “heartbeat” shape exhibiting multiple sign inversions, which might be mistaken for noise in the absence of theoretical guidance. We also conclude that there is a tendency for the V(λ) profile to integrate to zero on …