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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

The Sun as a star

Solar physics was reviewed in the context of the solar atmoshere. The understanding of the solar atmosphere is linked to stellar atmospheric research. Topics covered include: the existence of the chromosphere, the corona, and the solar wind; the interactive complex of convection, differential rotation, magnetic field generation and concentration, and the activity cycle; phenomena such as granulation, supergranulation, the 5 minute oscillation, filigree, faculae, sunspots, spicules, prominences, surges, and the spectacular flares.

Jordan, S. D.↗
NASA NTRS1995

Features of solar wind acceleration according to radio occultation data

In addressing one of the fundamental problems in solar physics establishing the mechanism(s) responsible for the solar wind acceleration and the corona heating - it is essential to have a reliable knowledge of the heliocentric radial dependence of the solar wind properties. Adequate data are available for small solar distances R less than 4 R(solar mass) from coronal white light and EUV observations and at distances R greater than 60 R(solar mass) from in situ measurements. One of the few methods available to fill in the gap between these boundaries is the radio scintillation technique. Taking the example of the solar wind velocity, the most reliable such measurements are obtained when phase fluctuation observations of scattered radio waves, which are not susceptible to saturation effects, are recorded at two or more widely-spaced ground stations. Two extensive observation campaigns of this type were carried out with the Venus-orbiting satellites Venera 10 in 1976 and Venera 15/16 in 1984. The observations were performed over the course of three months near superior conjunction at solar offset distances R approximately 6-80 R(solar mass). The main results from the subsequent analysis of these data are: (1) velocities vary between 250 and 380 km s(exp -1) for R greater than 20 R(solar mass), agreeing with similar measurements using natural sources (IPS); (2) velocities derived from two-station phase fluctuation observations varv between 70 and 120 km s(exp -1) for R less than 12 R(solar mass), i.e. values substantially lower than those derived from conventional IPS data; and (3) it is suggested that the different velocity profiles derived from the two data sets at small R may be due to the effects of magnetosonic and Alfvenic waves on radio wave scattering. Further analysis of additional radio sounding data should help resolve the apparent discrepancy.

Efimov, A. I.↗
NASA NTRS2007

Space Science Research and Technology at NASA's Marshall Space Flight Center

This presentation will summarize the various projects and programs managed in the Space Science Programs and Projects Office at NASA's Marshall Space Flight Center in Huntsville, Alabama. Projects in the portfolio include NASA's Chandra X-Ray telescope, Hinode solar physics satellite, various advanced space propulsion technologies, including solar sails and tethers, as well as NASA's Discovery and New Frontiers Programs.

Johnson, Charles L.↗
NASA NTRS1984

Solar-geophysical data number 479, August 1981. Part 2: (Comprehensive reports), data for January 1984 and August 1981 and miscellanea. Explanation of data reports issued as number 474 (supplement) February 1984

Various solar physical data are presented including: data for January 1984--(solar radio bursts af fixed frequencies, solar X-ray radiation from GOES satellite, Mass ejections from the sun); data for August 1981--solar flares; Miscellaneous data--(meudon carte synoptique, solar X-ray radiation from GOES satellite).

Coffey, H. E.↗
NASA NTRS1985

Spacelab to Space Station; Proceedings of the International Symposium on Spacelab 1 - Results, Implications and Perspectives, Naples and Capri, Italy, June 11-16, 1984

Consideration is given to the scientific objectives of the Spacelab program, a review of data obtained during the STS-9/Spacelab 1 mission on board the Shuttle, and the coordination of future Spacelab research among participating European nations. Among the specific fields of study covered by Spacelab 1 were space plasma physics, materials and fluid sciences and technology, astronomy and solar physics, and atmospheric physics and earth observations. Consideration is also given to the legal aspects of space manufacturing activities, the role of private industry in space-based manufacturing ventures, plant production and breeding in space, and the development of remote sensing systems for use in a microgravity environment.

Napolitano, L. G.↗
NASA NTRS2001

Did I Say Terabyte? I Meant Petabyte: Data Archiving in the Era of SDO

Two years ago (Gurman 1999, Bull, AAS, 31, 955), we discussed the treatment of archives of the order of 10 Tbyte per year from solar physics missions in the period 2004 - 2006 (e.g. Solar-B and STEREO). By early 2007, we expect that the Sun-Earth Connections community will have to deal with data sets from the Solar Dynamics Observatory (SDO) of order I Tbyte per day. As in the previous work, we examine several alternatives for dealing with data flow and service on a fire-hose scale, and show that off-the shelf, network-attached storage can provide an inexpensive and scaleable solution. We discuss some of the differences between an SDO data archive, as well as the range of requirements for data integrity, disaster recovery, &c. in various scenarios for archive concentration or distribution.

Gurman, Joseph B.↗
NASA NTRS1987

Data analysis and interpretation of UVSP and other experiments on board solar maximum mission

During the period of this contract (February 1 1980 to February 1987) there were two separate efforts involved: one was programmetric, i.e., the coordination of scientific working groups and the organization of workshops in the solar physics discipline; the second was scientific, i.e., to perform research to investigate the fundamental physical mechanisms of the energy and momentum transport from the solar surface to interplanetary space. In the former, 19 workshops, involving 88 scientists were organized. In the latter aspect, the following were investigated: solar flare energy buildup and release, coronal dynamics, energy and momentum transport from lower solar atmosphere to interplanetary space, numerical methods for the calculation of the nonlinear force-free field, and the evolution of the solar magnetic field.

Wu, S. T.↗
NASA NTRS1987

High-energy particle production in solar flares (SEP, gamma-ray and neutron emissions)

Electrons and ions, over a wide range of energies, are produced in association with solar flares. Solar energetic particles (SEPs), observed in space and near earth, consist of electrons and ions that range in energy from 10 keV to about 100 MeV and from 1 MeV to 20 GeV, respectively. SEPs are directly recorded by charged particle detectors, while X-ray, gamma-ray, and neutron detectors indicate the properties of the accelerated particles (electrons and ions) which have interacted in the solar atmosphere. A major problem of solar physics is to understand the relationship between these two groups of charged particles; in particular whether they are accelerated by the same mechanism. The paper reviews the physics of gamma-rays and neutron production in the solar atmosphere and the method by which properties of the primary charged particles produced in the solar flare can be deduced. Recent observations of energetic photons and neutrons in space and at the earth are used to present a current picture of the properties of impulsively flare accelerated electrons and ions. Some important properties discussed are time scale of production, composition, energy spectra, accelerator geometry. Particular attention is given to energetic particle production in the large flare on June 3, 1982.

Chupp, E. L.↗
NASA NTRSDate not supplied

The Hourly GHI, DHI and DNI: Intercomparison of the CERES-Based Data and the NSRDB Data through Comparison with the Ground-Based BSRN Data

The NASA Clouds and the Earth’s Radiant Energy System (CERES) SYN1deg(Ed4.1) provides hourly global horizontal irradiance (GHI), diffuse horizontal irradiance (DHI) and direct horizontal irradiance (DirHI) at 1-degree latitude by 1-degree longitude resolution, and the time span is from March 2000 to near present. While the GHI agrees well with the ground-based Baseline Surface Radiation Network (BSRN) data, the DHI and DirHI are, respectively, positively and negatively biased against the BSRN data, and so is the direct normal irradiance (DNI) derived simply by dividing the DirHI by the cosine of the hourly solar zenith angle (SZA). We found that the biases tend to be well-defined functions of cos(SZA) and the cloud fraction (CLFR). We thus performed a bias-correction on the hourly DHI and DNI in the latitude-cos(SZA)-CLFR phase space, and therefrom, we derived the hourly global tilted irradiance (GTI) at a number of tilt angles using the isotropic diffuse irradiance model, and the results agree well with the GTI derived from the original BSRN near-instantaneous records. Meanwhile, the National Renewable Energy Laboratory (NREL) has produced the National Solar Radiation Database (NSRDB) with finer spatiotemporal resolution using its Physical Solar Model (PSM) and surface-based measured data, model results and satellite-based data as inputs. Now the NSRDB data covers not only the United States and its neighboring regions, but Europe, Africa, Asia and Oceania. The available temporal resolutions are 5, 10, 15, 30 and 60 minutes and the spatial resolutions are 2, 4 and 10 km, depending on the selected region. In this presentation, we compare both the CERES-based and NSRDB GHI, DHI and DNI with their BSRN counterparts and show how finer spatial resolution may give us an advantage in data accuracy and usability.

Taiping Zhang↗
NASA NTRS1997

ISPAE Research Highlights 1995-1997

This paper presents ISPAE (Institute for Space Physics, Astrophysics and Education) research highlights from 1995-1997. The topics include: 1) High-Energy Astrophysics (Finding the smoking gun in gamma-ray bursts, Playing peekaboo with gamma ray bursts, and Spectral pulses muddle burst source study, Einstein was right: Black holes do spin, Astronomers find "one-man X-ray band", and Cosmic rays from the supernova next door?); 2) Solar Physics (Bright burst confirms solar storm model, Model predicts speed of solar wind in space, and Angry sunspots snap under the strain); 3) Gravitational Physics; 4) Tether Dynamics; and 5) Space Physics (Plasma winds blow form polar regions, De-SCIFERing thermal electrons, and UVI lets scientists see daytime aurora).

Harwell, Ken↗
NASA NTRS1990

The goals of gamma-ray spectroscopy in high energy astrophysics

The use of high resolution gamma-ray spectroscopy in astrophysics is discussed with specific attention given to the application of the Nuclear Astrophysics Explorer (NAE). The gamma-ray lines from nuclear transitions in radionucleic decay and positron annihilation permits the study of current sites, rates and models of nucleosynthesis, and galactic structure. Diffuse galactic emission is discussed, and the high-resolution observations of gamma-ray lines from discrete sites are also described. Interstellar mixing and elemental abundances can also be inferred from high-resolution gamma-ray spectroscopy of nucleosynthetic products. Compact objects can also be examined by means of gamma-ray emissions, allowing better understanding of neutron stars and the accreting black hole near the galactic center. Solar physics can also be investigated by examining such features as solar-flare particle acceleration and atmospheric abundances.

Lingenfelter, Richard E.↗
NASA NTRS1978

Solar neutron spectroscopy near the sun

A brief note is summarized to show the importance of solar neutron observations for the advancement of phenomena crucial for solar physics, and to suggest the constraints which must be placed on the Solar Probe Mission for carrying out studies of this kind.

Simpson, J. A.↗
NASA NTRS1992

Workshop on the evolution of the Martian atmosphere

Thirty-three papers based on the state of our knowledge prior to the anticipated new results from Mars Observer were presented at the workshop. Because of the nature of the subject, the scope of the papers covered a broad disciplinary range encompassing astronomy and solar physics, geology and geophysics, climatology, atmospheric science, aeronomy, and space physics. The 42 participants heard about topics from the evolution of solar-type stars to candidate instrumentation for measuring escape to space on yet-unscheduled future missions.

Luhmann, J. G.↗
NASA NTRS2001

Global Magnetohydrodynamic Modeling of the Solar Corona

The solar corona, the hot, tenuous outer atmosphere of the Sun, exhibits many fascinating phenomena on a wide range of scales. One of the ways that the Sun can affect us here at Earth is through the large-scale structure of the corona and the dynamical phenomena associated with it, as it is the corona that extends outward as the solar wind and encounters the Earth's magnetosphere. The goal of our research sponsored by NASA's Supporting Research and Technology Program in Solar Physics is to develop increasingly realistic models of the large-scale solar corona, so that we can understand the underlying properties of the coronal magnetic field that lead to the observed structure and evolution of the corona. We describe the work performed under this contract.

Linker, Jon A.↗
DOE OSTI2015

Artium mater in relativistic astrophysics : New perspectives for a European-Latin American PhD program

Following the successful scientific space missions by the European Space Agency (ESA) and the European Southern Observatory (ESO) in Chile, as well as the high-energy particle activities at CERN in Genve, we have created a Ph.D. program dedicated to the formation of scientists in the field of relativistic astrophysics. The students of such a program will lead the theoretical developments of one of the most active fields of research, based on the above observational and experimental facilities. This program needs expertise in the most advanced topics of mathematical and theoretical physics, and in relativistic field theories. It requires the ability to model the observational data received from the above facilities, as well as all the basic knowledge in astronomy, astrophysics and cosmology. This activity is necessarily international, no single university can cover the broad expertises. From this, the proposed program of the IRAP Ph.D., in one of the youngest and most dynamical French universities, pole of research and teaching in the Euro-Mediterranean region (PRES): the University of Nice. It benefits from the presence of the astrophysics research institute of Observatoire de la Cte d’Azur involved in relativistic and non-photonic astrophysics. The participation of the Freie Universitaet Berlin, Oldenburg and Bremen Universities and of the Einstein Institute in Potsdam offers the possibility of teaching in relativistic field theories at the highest level. The University of Savoy offers the link to the particle physics at CERN. The activities at the University of Rome, at Stockholm University and at ICRANet offer teaching programs in all the fields of relativistic astrophysics, including cosmology, the physics of gravitational collapse, gamma-ray bursts, and black hole physics. Finally, the University of Ferrara will be present with lectures and researches in the topics they have pioneered such as x-ray astrophysics and observational cosmology. Through ICRANet the extra-European connections with Brazil, China and India will be guaranteed: in China, with the Shanghai Observatory of the Chinese Academy of Science, studying the formation and evolution of large-scale structure and galaxies; in India, with the Indian Centre for Space Physics (ICSP), renowned for its research on compact objects as well as on solar physics and astrochemistry; in Brazil with ICRANet Brazil where a successful program of research and teaching in relativistic astrophysics has been established in recent years.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2017

The Direct Effect of Toroidal Magnetic Fields on Stellar Oscillations: An Analytical Expression for the General Matrix Element

Where is the solar dynamo located and what is its modus operandi? These are still open questions in solar physics. Helio- and asteroseismology can help answer them by enabling us to study solar and stellar internal structures through global oscillations. The properties of solar and stellar acoustic modes are changing with the level of magnetic activity. However, until now, the inference on subsurface magnetic fields with seismic measures has been very limited. The aim of this paper is to develop a formalism to calculate the effect of large-scale toroidal magnetic fields on solar and stellar global oscillation eigenfunctions and eigenfrequencies. If the Lorentz force is added to the equilibrium equation of motion, stellar eigenmodes can couple. In quasi-degenerate perturbation theory, this coupling, also known as the direct effect, can be quantified by the general matrix element. We present the analytical expression of the matrix element for a superposition of subsurface zonal toroidal magnetic field configurations. The matrix element is important for forward calculations of perturbed solar and stellar eigenfunctions and frequency perturbations. The results presented here will help to ascertain solar and stellar large-scale subsurface magnetic fields, and their geometric configuration, strength, and change over the course of activity cycles.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1986

The role of nonclassical electron transport in the lower solar transition region

One problem in solar physics is concerned with an understanding of the observed brightness of the quiet solar atmosphere in spectral lines which are formed in the lower solar transition region. The present paper has the objective to examine the possibility that the observed line emission results from nonclassical electron transport effects which are associated with the inherently steep temperature gradients in the solar transition region. The height variation of the electron temperature is parameterized to enable correspondence with a variety of one-dimensional constant pressure transition region models. The models include empirical models, theoretical models, and the constant classical heat fluxx model used by Shoub (1983). The electron velocity distribution function is considered along with the effect on collisional excitation and ionization rates, and effects on heat transport.

Owocki, S. P.↗
NASA NTRS1995

Helioseismology: A probe of the solar interior, atmosphere, and activity cycle

Helioseismology began in earnest in the mid 1970's. In the two decades which have elapsed since that time this branch of solar physics has become a mature field of research. Helioseismology has demonstrated that the solar convection zone is about twice as deep as was generally thought to be the case before 1977. Helioseismology has also provided measurements of the solar internal angular velocity over much of the sun's interior. Helioseismology has also ruled out models which would solve the solar neutrino problem by a lowering of the temperature of the core. Recently, some of the seismic properties of the sun have been demonstrated to vary with changing levels of solar activity. Also, helioseismology has recently provided evidence for helical flow patterns in the shallow, sub-photosphere layers. The techniques of helioseismology are also expanding to include seismic probes of solar active regions. Some work is also being conducted into the possible contributions of the solar acoustic models to the heating of the solar atmosphere. In this talk I will highlight a few of the above results and concentrate on current areas of research in the field.

Rhodes, E. J., Jr.↗