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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 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
NASA NTRS1998

Study of MeV/GeV/Sources. TeV Extension of First CGRO EGRET Catalogue Sources Multiwavelength Blazar Studies: A Search for TeV Emission from Bursts Detected by BATSE

The Whipple Gamma Ray Collaboration was formed in 1982 with the aim of improving the sensitivity of the ground-based atmospheric Cherenkov technique by the use of imaging cameras on large optical detectors. The approach was successful and the discipline of ground-based TeV astronomy was established. The first confirmed galactic source was discovered by the Whipple Collaboration as were the first two extragalactic sources. The technique has now matured and several new and important astrophysical results have been produced. The gamma-ray group of the Smithsonian Astrophysical Observatory is a key component of the Whipple Gamma Ray Collaboration. With all its members resident in Arizona, all its activities are devoted to research in ground-based gamma-ray astronomy.

Weekes, Trevor C.↗
NASA NTRS1990

Seeing in a new light: Astro-1 teacher's guide with activities

A teacher's guide that concentrates on the electromagnetic spectrum is presented. The subject was chosen because it is part of the middle school curriculum and because an understanding of the different ranges of energy is crucial to an understanding of the high energy astronomy performed by the Astro-1 telescopes to be carried on the Space Shuttle's first astrophysics mission. Various learning activities are outlined.

Source record↗
NASA NTRS1971

New astronomy space experiments with television scanning.

Application of data from the Celescope Catalog of Ultraviolet Observations to various problems of stellar and interstellar astrophysics. These include refinements in the incorporation of line blanketing in theoretical stellar-atmosphere models, variations in the law of interstellar extinction from one region of the sky to another, and selection and identification of various types of peculiar stars for further investigation. In addition, the data were analyzed to determine the photometric and astrometric accuracy of the Celescope equipment.

Davis, R. J.↗
NASA NTRS2011

High Broadband Spectral Resolving Transition-Edge Sensors for High Count-Rate Astrophysical Applications

We are developing arrays of transition-edge sensor (TES) X-ray detectors optimized for high count-rate solar astronomy applications where characterizing the high velocity motions of X-ray jets in solar flares is of particular interest. These devices are fabricated on thick Si substrates and consist of 35x35micron^2 TESs with 4.5micron thick, 60micron pitch, electroplated absorbers. We have tested devices fabricated with different geometric stem contact areas with the TES and surrounding substrate area, which allows us to investigate the loss of athermal phonons to the substrate. Results show a correlation between the stem contact area and a non-Gaussian broadening in the spectral line shape consistent with athermal phonon loss. When the contact area is minimized we have obtained remarkable board-band spectral resolving capabilities of 1.3 plus or minus 0.leV at an energy of 1.5 keV, 1.6 plus or minus 0.1 eV at 5.9 keV and 2.0 plus or minus 0.1 eV at 8 keV. This, coupled with a capability of accommodating 100's of counts per second per pixel makes these devices an exciting prospect of future x-ray astronomy applications.

Smith, Stephen↗
NASA NTRS2021

Gravitational-Wave Physics and Astronomy in the 2020s and 2030s

The 100 years since the publication of Albert Einstein’s theory of General Relativity saw significant development of the understanding of the theory, the identification of potential astrophysical sources of sufficiently strong gravitational waves, and development of key technologies for gravitational-wave detectors. In 2015, the first gravitational wave signals were detected by the two US Advanced LIGO instruments. In 2017, Advanced LIGO and the European Advanced Virgo detectors pinpointed a binary neutron star coalescence that was also seen across the electromagnetic spectrum. The field of gravitational wave astronomy is just starting, and this Roadmap of future developments surveys the potential for growth in bandwidth and sensitivity of future gravitational-wave detectors and discusses the science results anticipated to come from upcoming instruments.

Compact astrophysical objects↗
NASA NTRS2016

Initial Technology Assessment for the Large-Aperture UV-Optical-Infrared (LUVOIR) Mission Concept Study

The NASA Astrophysics Division's 30-Year Roadmap prioritized a future large-aperture space telescope operating in the ultra-violet/optical/infrared wavelength regime. The Association of Universities for Research in Astronomy envisioned a similar observatory, the High Definition Space Telescope. And a multi-institution group also studied the Advanced Technology Large Aperture Space Telescope. In all three cases, a broad science case is outlined, combining general astrophysics with the search for biosignatures via direct-imaging and spectroscopic characterization of habitable exoplanets. We present an initial technology assessment that enables such an observatory that is currently being studied for the 2020 Decadal Survey by the Large UV/Optical/Infrared (LUVOIR) surveyor Science and Technology Definition Team. We present here the technology prioritization for the 2016 technology cycle and define the required technology capabilities and current state-of-the-art performance. Current, planned, and recommended technology development efforts are also reported.

technology development↗
NASA NTRS2016

Initial Technology Assessment for the Large UV-Optical-Infrared (LUVOIR) Mission Concept Study

The NASA Astrophysics Divisions 30-Year Roadmap prioritized a future large-aperture space telescope operating in the ultra-violet-optical-infrared wavelength regime. The Association of Universities for Research in Astronomy envisioned a similar observatory, the High Definition Space Telescope. And a multi-institution group also studied the Advanced Technology Large Aperture Space Telescope. In all three cases, a broad science case is outlined, combining general astrophysics with the search for bio-signatures via direct-imaging and spectroscopic characterization of habitable exo-planets. We present an initial technology assessment that enables such an observatory that is currently being studied for the 2020 Decadal Survey by the Large UV-Optical Infrared (LUVOIR) surveyor Science and Technology Definition Team. We present here the technology prioritization for the 2016 technology cycle and define the required technology capabilities and current state-of-the-art performance. Current, planned, and recommended technology development efforts are also reported.

large aperture↗
NASA NTRS1973

High energy and solar astronomy, overview

A survey of our own galaxy and neighboring galaxies using X-rays, gamma rays, and cosmic rays is outlined. High energy astrophysic results suggest the presence of a new acceleration mechanism where the inflow of matter on collapsed objects seems to be one of the sources of complex time variations in binary systems.

Mcdonald, F. B.↗
NASA NTRS1991

High resolution gamma-ray astronomy - Observations and predictions of line shapes

The shapes of gamma-ray lines carry unique information about the physical processes and conditions in astrophysical sites. Galactic center and SN 1987A lines have been observationally resolved allowing their shapes to be studied. There are also significant new theoretical results concerning line shapes from Type I supernovae, supernova remnants and the interstellar medium. New work is presented on a simple treatment of line profiles for rotating disks and spherical shells.

Bhattacharya, Dipen↗
NASA NTRS1992

Intelligent text retrieval in the NASA astrophysics data system

In collaboration with the NASA Scientific and Technical Information System, the NASA Astrophysics Data System (ADS) is establishing a service to provide access to the literature abstracts relevant to astronomy in the NASA Scientific and Technical Aerospace Reports and the International Aerospace Abstracts (together also known as NASA RECON). The service will include several sophisticated retrieval methods, which may be combined. Included will be methods to perform relevancy ranking from natural language queries, synonym and misspelling recognition, author name translation (e.g. for multiple transliteration possibilities), and other features. The capabilities of the current release will be shown, and the plans for the near future will be discussed.

Kurtz, M. J.↗
NASA NTRS2000

Infrared Submillimeter and Radio Astronomy Research and Analysis Program

This program entitled "Infrared Submillimeter and Radio Astronomy Research and Analysis Program" with NASA-Ames Research Center (ARC) was proposed by the Smithsonian Astrophysical Observatory (SAO) to cover three years. Due to funding constraints only the first year installment of $18,436 was funded, but this funding was spread out over two years to try to maximize the benefit to the program. During the tenure of this contact, the investigators at the SAO, Drs. Wesley A. Traub and Nathaniel P. Carleton, worked with the investigators at ARC, Drs. Jesse Bregman and Fred Wittebom, on the following three main areas: 1. Rapid scanning SAO and ARC collaborated on purchasing and constructing a Rapid Scan Platform for the delay arm of the Infrared-Optical Telescope Array (IOTA) interferometer on Mt. Hopkins, Arizona. The Rapid Scan Platform was tested and improved by the addition of stiffening plates which eliminated a very small but noticeable bending of the metal platform at the micro-meter level. 2. Star tracking Bregman and Wittebom conducted a study of the IOTA CCD-based star tracker system, by constructing a device to simulate star motion having a specified frequency and amplitude of motion, and by examining the response of the tracker to this simulated star input. 3. Fringe tracking. ARC, and in particular Dr. Robert Mah, developed a fringe-packet tracking algorithm, based on data that Bregman and Witteborn obtained on IOTA. The algorithm was tested in the laboratory at ARC, and found to work well for both strong and weak fringes.

Traub, Wesley A.↗
NASA NTRS2000

The AstroBiology Explorer (ABE) MIDEX Mission

The Astrobiology Explorer (ABE) is a Medium-Class Explorer (MIDEX) mission concept currently under study at NASA's Ames Research Center. ABE will conduct infrared (IR) spectroscopic observations with much better sensitivity than Infrared Space Observatory (ISO) or the Stratospheric Observatory for Infrared Astronomy program (SOFIA) in order to address outstanding astrobiologically important problems in astrochemistry as well as important astrophysical investigations. The core observational astrobiology program would make fundamental scientific progress in understanding the cosmic history of molecular carbon, the distribution of organic matter in the diffuse interstellar medium, tracing the chemical history of complex organic molecules in the interstellar medium, and the evolution of organic ices in young planetary systems. The ABE instrument concept includes a 0.5 m aperture Cassegrain telescope and a suite of three moderate resolution (R = 1000 - 4000) spectrographs which cover the entire lambda = 2.5-20 micron spectral region. Use of large format (1024 x 1024 pixel or larger) IR detector arrays will allow each spectrograph to cover an entire octave of spectral range per exposure without any moving parts. The telescope is passively cooled by a sun shade to below 65 K, and the detectors are cooled with solid H2 cryogen to approximately 8 K. ABE will be placed in an Earth-trailing one AU solar orbit by a Delta II launch vehicle. This energetically favorable orbit provides a low thermal background, affords good access to the entire sky over the one year mission lifetime, and allows adequate communications bandwidth. The spacecraft will be stabilized in three axes and will be pointed to an accuracy of approximately one arcsecond at ABE's several thousand individual scientific targets.

Greene, Thomas↗
NASA NTRS2001

Determination of the Cosmic Radio Background from the Radio-Infrared Relation in Galaxies

We use the radioactive flux correlation for star forming galaxies in the local universe to derive their contribution to the cosmic radio background (CRB). The CRB from these galaxies is therefore determined by the evolution of the comoving infrared luminosity density with redshift, which is constrained by galaxy number counts at various infrared wavelengths and by the cosmic infrared background. The research of ED was supported by NASA NRA 99-OSS-01 Astrophysics Theory Program. MB acknowledges the support of the "Research Opportunities for Undergraduates in the Laboratory for Astronomy and Solar Physics" for the summer student internship program at NASA/GSFC.

Dwek, Eli↗
NASA NTRS2000

Chandra and XMM-Newton: Atomic Data Needs For X-ray Astronomy

With the launches of the Chandra X-ray Observatory and XM M-Newton, high resolution X-ray spectra of cosmic sources are broadening our understanding of the physical conditions, such as temperature, density, Ionization state, and elemental abundances. X-ray emitting astrophysical plasmas can be generally classified by their dominant ionization mechanism, either collisional ionization or X-ray photoionization. The atomic data needs are significantly different for these two cases; however, for both cases it is important that we identify robust and accurate diagnostics and that we verify completeness of the broadband models. We discuss the status of tile atomic data currently used in atomic databases for X-ray astronomy, in view of theoretical and experimental atomic physics considerations. We will also discuss the application of these models to new astrophysical data.

Brickhouse, Nancy↗
NASA NTRS1984

A solar spectral line list between 10 and 200 A modified for application to high spectral resolution X-ray astronomy

A spectral line list for the 10-200 A range is developed from existing solar spectra for application to high spectral resolution measurements of astrophysical plasmas. The solar spectral line lists are merged into a single comprehensive list. The effect of the solar emission measure distribution is removed from the line intensities, which results in a set of emission rates for the lines that can be applied to many optically thin, low density high temperature plasmas in ionization equilibrium. In addition to the measured solar lines, 250 theoretical lines are added to this list. These lines fall in wavelength regions where the existing solar lists have few lines because of limitations in instrumental sensitivity. Also, some lines have been added because the sun has very little plasma at temperatures of about one million K, and consequently these lines are weak or absent in solar spectra. The entire list contains about 600 lines. Finally, predicted spectra of the two RS CVn stars, alpha Aur (Capella) and UX Ari, are presented at 1 and 0.25 A spectral resolution. Also, the solar spectrum is shown at 1 A resolution, and the emission rate spectrum (spectrum not modified by an emission measure distribution) is shown at very high spectral resolution. The predicted spectra for Capella and UX Ari are based on results obtained from the Einstein and International Ultraviolet Explorer (IUE) spacecraft.

Doschek, G. A.↗
NASA NTRS1986

Topics in gamma ray astronomy

Observations of gamma rays from solar flares, gamma ray bursts, the Galactic center, galactic nucleosynthesis, SS433, and Cygnus X-3, and their effects on astrophysical problems are discussed. It is observed that gamma ray spectra from solar flares are applicable to the study of particle acceleration and confinement and the determination of chemical abundances in the solar atmosphere. The gamma ray lines from the compact galactic object SS433 are utilized to examine the acceleration of jets, and analysis of the gamma ray lines of Cygnus X-3 reveal that particles can be accelerated in compact sources to ultrahigh energies.

Ramaty, R.↗
NASA NTRSDate not supplied

Design and Performance of the CdZnTe VFG Imaging Calorimeter Prototype for Gamma-ray Astronomy

We present the design and first results of the CdZnTe Imaging calorimeter prototype. The CdZnTe Imaging calorimeter has been designed for use in large astrophysical gamma-ray space instruments, and we report here on a small prototype built to validate the approach. The calorimeter is based on virtual Frisch-grid drift-bar CdZnTe detectors. The design is modular, such that multiple crates of 16 bars, each served by a single ASIC, can be arranged in to different configurations depending on the specific requirements for an instrument. The modules are plugged into the readout motherboard in the designed configuration for a given instrument. The detectors are capable of measuring the interaction point of an incident photon in three dimensions and the energy deposited. In this work, we have designed and built a prototype consisting of 4 by 4 module array and have tested it with various radioactive sources to measure its position and energy resolution. The preliminary results demonstrate ~1% FWHM energy resolution and 1-2 mm position resolution for 662 keV photons (Cs137), subject to the further improvement by applying various corrections. We tested the module with a “conventional” analog ASIC readout as well as a wave-front sampling ASIC to compare the results, which is critical for the optimization of the future instrument.

A. A. Moiseev↗
NASA NTRS2009

X-Ray Calorimeter Arrays for Astrophysics

High-resolution x-ray spectroscopy is a powerful tool for studying the evolving universe. The grating spectrometers on the XMM and Chandra satellites started a new era in x-ray astronomy, but there remains a need for instrumentation that can provide higher spectral resolution with high throughput in the Fe-K band (around 6 keV) and can enable imaging spectroscopy of extended sources, such as supernova remnants and galaxy clusters. The instrumentation needed is a broad-band imaging spectrometer - basically an x-ray camera that can distinguish tens of thousands of x-ray colors. The potential benefits to astrophysics of using a low-temperature calorimeter to determine the energy of an incident x-ray photon via measurement of a small change in temperature was first articulated by S. H. Moseley over two decades ago. In the time since, technological progress has been steady, though full realization in an orbiting x-ray telescope is still awaited. A low-temperature calorimeter can be characterized by the type of thermometer it uses, and three types presently dominate the field. The first two types are temperature-sensitive resistors - semiconductors in the metal-insulator transition and superconductors operated in the superconducting-normal transition. The third type uses a paramagnetic thermometer. These types can be considered the three generations of x-ray calorimeters; by now each has demonstrated a resolving power of 2000 at 6 keV, but only a semiconductor calorimeter system has been developed to spaceflight readiness. The Soft X-ray Spectrometer on Astro-H, expected to launch in 2013, will use an array of silicon thermistors with I-IgTe x-ray absorbers that will operate at 50 mK. Both the semiconductor and superconductor calorimeters have been implemented in small arrays, kilo-pixel arrays of the superconducting calorimeters are just now being produced, and it is anticipated that much larger arrays will require the non-dissipative advantage of magnetic thermometers.

Kilbourne, Caroline A.↗