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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 955 records · Page 53
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

AN INFRARED DIFFUSE CIRCUMSTELLAR BAND? THE UNUSUAL 1.5272 μm DIB IN THE RED SQUARE NEBULA

The molecular carriers of the ubiquitous absorption features called the diffuse interstellar bands (DIBs) have eluded identification for many decades, in part because of the enormous parameter space spanned by the candidates and the limited set of empirical constraints afforded by observations in the diffuse interstellar medium. Detection of these features in circumstellar regions, where the environmental properties are more easily measured, is thus a promising approach to understanding the chemical nature of the carriers themselves. Here, using high-resolution spectra from the Apache Point Observatory Galactic Evolution Experiment survey, we present an analysis of the unusually asymmetric 1.5272 μm DIB feature along the sightline to the Red Square Nebula (RSN) and demonstrate the likely circumstellar origin of about half of the DIB absorption in this line of sight. This interpretation is supported both by the velocities of the feature components and by the ratio of foreground to total reddening along the line of sight. The RSN sightline offers the unique opportunity to study the behavior of DIB carriers in a constrained environment and thus to shed new light on the carriers themselves.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2017

Recent Progress in Laboratory Astrophysics and Astrochemistry Achieved with the COSmIC Facility

We describe the characteristics and the capabilities of the laboratory facility, COSmIC, that was developed at NASA Ames to generate, process and analyze interstellar, circumstellar and planetary analogs in the laboratory. COSmIC stands for "Cosmic Simulation Chamber" and is dedicated to the study of neutral and ionized molecules and nanoparticles under the low temperature and high vacuum conditions that are required to simulate various space environments such as diffuse interstellar clouds, circumstellar outflows and planetary atmospheres. COSmIC integrates a variety of state-of-the-art instruments that allow recreating simulated space conditions to generate, process and monitor cosmic analogs in the laboratory. The COSmIC experimental setup is composed of a Pulsed Discharge Nozzle (PDN) expansion, that generates a plasma in the stream of a free supersonic jet expansion, coupled to high-sensitivity, complementary in situ diagnostics: cavity ring down spectroscopy (CRDS) and laser induced fluorescence (LIF) systems for photonic detection, and Reflectron Time-Of-Flight Mass Spectrometer (ReTOF-MS) for mass detection. Recent results obtained using COSmIC will be highlighted. In particular, the progress that has been achieved in the domain of the diffuse interstellar bands (DIBs) and in monitoring, in the laboratory, the formation of circumstellar dust grains and planetary atmosphere aerosols from their gas-phase molecular precursors. Plans for future laboratory experiments on interstellar and planetary molecules and grains will also be addressed, as well as the implications of the studies underway for astronomical observations and past and future space mission data analysis.

Salama, Farid↗
NASA NTRS2016

Development of the Model of Galactic Interstellar Emission for Standard Point-Source Analysis of Fermi Large Area Telescope Data

Most of the celestial gamma rays detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope originate from the interstellar medium when energetic cosmic rays interact with interstellar nucleons and photons. Conventional point-source and extended-source studies rely on the modeling of this diffuse emission for accurate characterization. Here, we describe the development of the Galactic Interstellar Emission Model (GIEM),which is the standard adopted by the LAT Collaboration and is publicly available. This model is based on a linear combination of maps for interstellar gas column density in Galactocentric annuli and for the inverse-Compton emission produced in the Galaxy. In the GIEM, we also include large-scale structures like Loop I and the Fermi bubbles. The measured gas emissivity spectra confirm that the cosmic-ray proton density decreases with Galactocentric distance beyond 5 kpc from the Galactic Center. The measurements also suggest a softening of the proton spectrum with Galactocentric distance. We observe that the Fermi bubbles have boundaries with a shape similar to a catenary at latitudes below 20deg and we observe an enhanced emission toward their base extending in the north and south Galactic directions and located within approximately 4deg of the Galactic Center.

gamma rays: diffuse background – gamma rays: gen↗
NASA NTRS1996

The Properties of the local Interstellar Medium and the Interaction of the Stellar Winds of epsilon Indi and lambda Andromedae with the Interstellar Environment

We present new observations of the Ly alpha lines of Epsilon Indi (K5 5) and A Andromedae (G8 4-3 + ?) These data were obtained by the Goddard High Resolution Spectrograph (GHRS) on the Hubble Space Telescope. Analysis of the interstellar H 1 and D 1 absorption lines reveals that the velocities and temperatures inferred from the H 1 lines are inconsistent with the parameters inferred from the D 1 lines, unless the H 1 absorption is assumed to be produced by two absorption components. One absorption component is produced by interstellar material. For both lines of sight observed, the velocity of this component is consistent with the velocity predicted by the local flow vector. For the Epsilon Indi data, the large velocity separation between the stellar emission and the interstellar absorption allows us to measure the H 1 column density independent of the shape of the intrinsic stellar Ly alpha profile. This approach permits us to quote an accurate column density and to assess its uncertainty with far more confidence than in previous analyses, for which the errors were dominated by uncertainties in the assumed stellar profiles.

Wood, Brian E.↗
NASA NTRS2013

Synthesis and Spectroscopy of Large Carbon Molecules with Ames' COSmIC Facility in Support of NASA's Space Missions

We present and discuss the unique characteristics and capabilities of the laboratory facility, COSmIC, that was developed at NASA Ames to generate, process and analyze interstellar and planetary analogs in the laboratory. COSmIC stands for Cosmic Simulation Chamber and is dedicated to the study of molecules and ions under the low temperature and high vacuum conditions that are required to simulate interstellar, circumstellar and planetary physical environments in space. COSmIC integrates a variety of state-of-the-art instruments that allow forming, processing and monitoring simulated space conditions for planetary, circumstellar and interstellar materials in the laboratory. COSmIC is composed of a Pulsed Discharge Nozzle (PDN) expansion that generates a free jet supersonic expansion coupled to two ultrahigh-sensitivity, complementary in situ diagnostics: a Cavity Ring Down Spectroscopy (CRDS) system for photonic detection and a Reflectron Time-Of-Flight Mass Spectrometer (ReTOF-MS) for mass detection. Recent, unique, laboratory astrophysics results that were obtained using the capabilities of COSmIC will be discussed, in particular the progress that have been achieved in monitoring in the laboratory the formation of solid gains from their gas-phase molecular precursors in environments as varied as stellar/circumstellar outflow and planetary atmospheres. Plans for future, next generation, laboratory experiments on cosmic molecules and grains in the growing field of laboratory astrophysics will also be addressed.

Spectroscopy↗
NASA NTRS2018

The Nature of Interstellar Organics and Their Relationship to the Solar System

Carbonaceous materials are a primary compo-nent of interstellar dust, forming in the outflow of carbon stars and the diffuse interstellar me-dium (DISM). Over time, the low density DISM is swept into dense molecular clouds, the principal formation sites and repositories of most interstellar molecules. Organic com-pounds created in these clouds are the first step towards the complex materials that help to make planets habitable. Ground- and space-based telescopic observations trace interstellar organics from the diffuse to dense interstellar clouds, revealing that organic material in the diffuse ISM is predominantly hydrocarbon in nature, possessing little N or O, with the C distributed between the aromatic and aliphatic forms. A remarkable similarity between the hydrocarbons in dust in our Galaxy to that of distant galaxies, indicates that this organic component of the DISM is widespread and may be an important universal reservoir of prebiotic organic carbon. Spectroscopy of background stars seen through quiescent dust in clouds with no star formation activity re-veals that chemistry occurs early-on. Mean-while, observations of certain asteroids, com-ets, interplanetary dust particles, planets and planetary satellites present an intricate inter-weaving of preserved interstellar components and those that have been subsequently altered. The composition ofinterstellar dust grains and the evolution of dust between dense clouds (where stars and planetary systems form) and the diffuse inter-stellar medium (where stardust components are ejected), will be presented in this workshop on Carbon in the Solar System.

Intersteller Organics↗
NASA NTRS1992

Atomic and molecular data for space astronomy - Needs, analysis, and availability; 21st IAU General Assembly, Buenos Aires, Argentina, July 23-Aug. 1, 1991, Selected Papers

The present volume on atomic and molecular spectroscopic data for space astrophysics discusses scientific problems and laboratory data needs associated with the Hubble Space Telescope, atomic data needed for far ultraviolet astronomy with HUT and FUSE and for analysis of EUV and X-ray spectra, and data for observations of interstellar medium with the Hubble Space Telescope. Attention is also given to atomic and molecular data for analysis of IR spectra from ISO and SIRTF, atomic data from the opacity project, sources of atomic spectroscopic data for astrophysics, and summary of current molecular data bases.

Smith, Peter L.↗
NASA NTRS2007

Extraterrestrial Samples at JSC

A viewgraph presentation on the curation of extraterrestrial samples at NASA Johnson Space Center is shown. The topics include: 1) Apollo lunar samples; 2) Meteorites from Antarctica; 3) Cosmic dust from the stratosphere; 4) Genesis solar wind ions; 5) Stardust comet and interstellar grains; and 5) Space-Exposed Hardware.

Allen, Carlton C.↗
DOE OSTI2015

Molecular ions in the laboratory and in space

Molecular ions play a central role in the gas-phase chemistry of the interstellar medium; they also provide information on the physical conditions in astronomical sources (e.g., fractional ionization), and in some cases can be used to infer the abundance of nonpolar molecules such as N{sub 2} and CO{sub 2} which can not be observed in the radio band. During the past four years, the rotational spectra of six carbon-chain anions (C{sub 2}H{sup −}, C{sub 4}H{sup −}, C{sub 6}H{sup −}, C{sub 8}H{sup −}, CN{sup −}, C{sub 3}N{sup −}), NCO{sup −} and seven protonated species (HSCO{sup +}, HSCS{sup +}, cis- and trans-HOSO{sup +}, H{sub 2}NCO{sup +}, HNCOH{sup +}, and HNNO{sup +}) have been detected in our laboratory. On the basis of dedicated astronomical searches, all of the carbon-chain anions except C{sub 2}H{sup −} have now been identified in space. In addition to highlighting recent work on carbon-chain anions and protonated HSO{sub 2}{sup +}, efforts to better understand the distribution of anions in space using C{sub 6}H{sup −} as a tracer for negative charge are described.

74 ATOMIC AND MOLECULAR PHYSICS↗
NASA NTRS1993

Radiative Cooling of Warm Molecular Gas

We consider the radiative cooling of warm (T >= 100 K), fully molecular astrophysical gas by rotational and vibrational transitions of the molecules H2O, CO, and H2. Using an escape probability method to solve for the molecular level populations, we have obtained the cooling rate for each molecule as a function of temperature, density, and an optical depth parameter. A four-parameter expression proves useful in fitting the run of cooling rate with density for any fixed values of the temperature and optical depth parameter. We identify the various cooling mechanisms which are dominant in different regions of the astrophysically relevant parameter space. Given the assumption that water is very abundant in warm regions of the interstellar medium, H2O rotational transitions are found to dominate the cooling of warm interstellar gas over a wide portion of the parameter space considered. While chemical models for the interstellar medium make the strong prediction that water will be produced copiously at temperatures above a few hundred degrees, our assumption of a high water abundance has yet to be tested observationally. The Infrared Space Observatory and the Submillimeter Wave Astronomy Satellite will prove ideal instruments for testing whether water is indeed an important coolant of interstellar and circumstellar gas.

Neufeld, David A.↗
DOE OSTI2015

The Spitzer c2d survey of large, nearby, interstellar clouds. XII. The Perseus YSO population as observed with IRAC and MIPS

The Spitzer Space Telescope mapped the Perseus molecular cloud complex with the Infrared Array Camera (IRAC) and the Multi-Band Imaging Photometer for Spitzer (MIPS) as part of the c2d Spitzer Legacy project. This paper combines the observations from both instruments giving an overview of low-mass star formation across Perseus from 3.6 to 70 μm. We provide an updated list of young stellar objects (YSOs) with new classifications and source fluxes from previous works, identifying 369 YSOs in Perseus with the Spitzer data set. By synthesizing the IRAC and MIPS maps of Perseus and building on the work of previous papers in this series, we present a current census of star formation across the cloud and within smaller regions. Sixty-seven percent of the YSOs are associated with the young clusters NGC 1333 and IC 348. The majority of the star formation activity in Perseus occurs in the regions around the clusters to the eastern and western ends of the cloud complex. The middle of the cloud is nearly empty of YSOs despite containing regions of high visual extinction. The western half of Perseus contains three-quarters of the total number of embedded YSOs (Class 0+I and Flat spectral energy distribution sources) in the cloud and nearly as many embedded YSOs as Class II and III sources. Class II and III objects greatly outnumber Class 0+I objects in eastern Perseus and IC 348. These results are consistent with previous age estimates for the clusters. Across the cloud, 56% of YSOs and 91% of the Class 0+I and Flat sources are in areas where A v ≪ 5 mag, indicating a possible extinction threshold for star formation.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1993

Cirrus and Future Space Based Astronomy

Astronomical observations from space make possible observations of sensitivity and spatial resolution impossible in the past. This increase in sensitivity will both make possible the observation of new phenomena and will bring observations against limitations not encountered before. This paper discusses the effects that infrared cirrus and diffuse interstellar clouds will have on space based observations. Some special opportunities provided by space observations of cirrus are presented and a partial list of currently planned observations of cirrus by space telescopes is given.

cirrus observations sensitivity stellar clouds spa↗
NASA NTRS2007

Useful Sensor Web Capabilities to Enable Progressive Mission Autonomy

This viewgraph presentation reviews using the Sensor Web capabilities as an enabling technology to allow for progressive autonomy of NASA space missions. The presentation reviews technical challenges for future missions, and some of the capabilities that exist to meet those challenges. To establish the ability of the technology to meet the challenges, experiments were conducted on three missions: Earth Observing 1 (EO-1), Cosmic Hot Interstellar Plasma Spectrometer (CHIPS) and Space Technology 5 (ST-5). These experiments are reviewed.

Mandl, Dan↗
DOE OSTI2015

Lifetimes and oscillator strengths for ultraviolet transitions in singly ionized lead

We present the results of lifetime measurements made using beam-foil techniques on levels of astrophysical interest in Pb ii producing lines at 1203.6 Å (6s6p{sup 2} {sup 2}D{sub 3/2}) and 1433.9 Å (6s{sup 2}6d {sup 2}D{sub 3/2}). We also report the first detection of the Pb ii λ1203 line in the interstellar medium (ISM) from an analysis of archival spectra acquired by the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope (HST). The oscillator strengths derived from our experimental lifetimes for Pb ii λλ1203, 1433 are generally consistent with recent theoretical results, including our own relativistic calculations. Our analysis of high-resolution HST/STIS spectra helps to confirm the relative strengths of the Pb ii λλ1203, 1433 lines. However, the oscillator strength that we obtain for Pb ii λ1433 (0.321 ± 0.034) is significantly smaller than earlier theoretical values, which have been used to study the abundance of Pb in the ISM. Our revised oscillator strength for λ1433 yields an increase in the interstellar abundance of Pb of 0.43 dex over determinations based on the value given by Morton, indicating that the depletion of Pb onto interstellar dust grains is less severe than previously thought.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2001

Interstellar Propulsion Research Within NASA

NASA is actively conducting advanced propulsion research and technology development in various in-space transportation technologies with potential application to interstellar missions and precursors. Within the last few years, interest in the scientific community in interstellar missions as well as outer heliospheric missions, which could function as interstellar precursor missions, has increased. A mission definition team was charted by NASA to define such a precursor, The Interstellar Probe, which resulted in a prioritization of relatively near-term transportation technologies to support its potential implementation. In addition, the goal of finding and ultimately imaging extra solar planets has raised the issue of our complete inability to mount an expedition to such as planet, should one be found. Even contemplating such a mission with today's technology is a stretch of the imagination. However, there are several propulsion concepts, based on known physics, that have promise to enable interstellar exploration in the future. NASA is making small, incremental investments in some key advanced propulsion technologies in an effort to advance their state-of-the-art in support potential future mission needs. These technologies, and their relative maturity, are described.

Johnson, Les↗
DOE OSTI2016

SOLAR MODULATION OF THE LOCAL INTERSTELLAR SPECTRUM WITH VOYAGER 1 , AMS-02, PAMELA , AND BESS

In recent years, the increasing precision of direct cosmic rays measurements opened the door to high-sensitivity indirect searches of dark matter and to more accurate predictions for radiation doses received by astronauts and electronics in space. The key ingredients in the study of these phenomena are the knowledge of the local interstellar spectrum (LIS) of galactic cosmic rays and the understanding of how the solar modulation affects the LIS inside the heliosphere. Voyager 1 , AMS-02, PAMELA , and BESS measurements of proton and helium fluxes provide valuable information, allowing us to shed light on the shape of the LIS and the details of the solar modulation during solar cycles 22-24. A new parametrization of the LIS is presented, based on the latest data from Voyager 1 and AMS-02. Using the framework of the force-field approximation, the solar modulation parameter is extracted from the time-dependent fluxes measured by PAMELA and BESS . A modified version of the force-field approximation with a rigidity-dependent modulation parameter is introduced, yielding better fits than the force-field approximation. The results are compared with the modulation parameter inferred by neutron monitors.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1992

Spatial heterodyne spectroscopy for the exploration of diffuse interstellar emission lines at far-ultraviolet wavelengths

Spatial heterodyne spectroscopy (SHS) is a new instrumental technique for interference spectroscopy which promises to extend into the FUV (1200-2000 A) spectral region the large throughput advantage at high spectral resolution usually associated with Fabry-Perot and Michelson interferometers. In addition, SHS systems are compact in size, can be field-widened to increase their throughput even further, have no moving parts, and can be built in all-reflection configurations. SHS appears to be well suited for high resolution, space-based spectroscopy of faint interstellar emission lines in the ultraviolet. This has significant implications for the study of the dynamics and distribution of hot gas within the Galactic disk and halo. For example, a field-widened SHS incorporating 5 x 5 cm gratings could obtain a radial velocity resolved (20 km/s), 3 deg angular resolution map of the high-latitude interstellar C IV 1550 emission in less than 1 year.

Harlander, J.↗
NASA NTRS1976

Observations of interstellar helium with a gas absorption cell - Limits on the bulk velocity of the interstellar medium

Results are reported for observations of solar 584-A flux resonantly scattered by the 1s(2)-1s2p transition of neutral interstellar helium. A photometer equipped with a helium gas-absorption cell and flown aboard a sounding rocket to a peak altitude of 185 km was employed to observe the sky in Perseus. The data reduction procedure is described, including subtraction of the terrestrial atmospheric background, calculation of the solar flux, and reduction of the number density of scatters to a function of phase-space parameters of the local interstellar medium. The ratio of 584-A fluxes observed with the gas cell full and empty is computed and compared with numerical models of the interstellar-helium flow through the solar system. The results show that the bulk speed of the distant interstellar medium with respect to the sun is unlikely to be less than 10 to 15 km/s, at the 2-sigma level. Since this value is inconsistent with results obtained from Lyman-alpha observations, it is suggested that either the total ionization rate for helium is variable or present models of the behavior of the local interstellar medium need further refinement.

Freeman, J.↗