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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

The stellar coronal X-ray Explorer: STCOEX

The status of the newly born field of stellar X-ray astronomy is considered. The need for further observational capability, the study of stellar surface activity and the development of design criteria for a follow-up mission, with primary emphasis on stellar observations and with general capabilities within the scope of the Explorer program are examined. The criteria which lead to the desired instrumental capabilities are reviewed; and an overview of the proposed instrument and some of its capabilities, as indicated by simulations is presented. Two versions of a trial payload the stellar coronal. Explorer (STCOEX) which meet the observational desirable are developed.

Vaiana, G. S.↗
NASA NTRS1991

The first year of observations with the Hubble Space Telescope

The Hubble Space Telescope has gathered unique information that supports many very significant scientific investigations during its early orbital operations, despite the limitations imposed by an unexpected spherical aberration in the primary mirror. These early results, gathered primarily with the HST cameras and spectrographs, are reviewed, with emphasis on extragalactic, stellar, and nebular astronomy.

Kinney, A. L.↗
NASA NTRS2011

Development of a Multivariable Parametric Cost Analysis for Space-Based Telescopes

Over the past 400 years, the telescope has proven to be a valuable tool in helping humankind understand the Universe around us. The images and data produced by telescopes have revolutionized planetary, solar, stellar, and galactic astronomy and have inspired a wide range of people, from the child who dreams about the images seen on NASA websites to the most highly trained scientist. Like all scientific endeavors, astronomical research must operate within the constraints imposed by budget limitations. Hence the importance of understanding cost: to find the balance between the dreams of scientists and the restrictions of the available budget. By logically analyzing the data we have collected for over thirty different telescopes from more than 200 different sources, statistical methods, such as plotting regressions and residuals, can be used to determine what drives the cost of telescopes to build and use a cost model for space-based telescopes. Previous cost models have focused their attention on ground-based telescopes due to limited data for space telescopes and the larger number and longer history of ground-based astronomy. Due to the increased availability of cost data from recent space-telescope construction, we have been able to produce and begin testing a comprehensive cost model for space telescopes, with guidance from the cost models for ground-based telescopes. By separating the variables that effect cost such as diameter, mass, wavelength, density, data rate, and number of instruments, we advance the goal to better understand the cost drivers of space telescopes.. The use of sophisticated mathematical techniques to improve the accuracy of cost models has the potential to help society make informed decisions about proposed scientific projects. An improved knowledge of cost will allow scientists to get the maximum value returned for the money given and create a harmony between the visions of scientists and the reality of a budget.

Dollinger, Courtnay↗
NASA NTRSDate not supplied

What Can We Learn From The Skies Of Alien Planets? Astrophysicists Tell All.

This panel will explore the exciting and often speculative topic of what the skies of other worlds might look like. The discussion will delve into both the scientific research that informs our understanding of exoplanet atmospheres and the creative and imaginative ways that artists and writers have depicted alien skies in popular culture. The panel will bring together experts across stellar and planetary astronomy to discuss the latest scientific findings about exoplanet atmospheres and what they might reveal about the potential habitability of these worlds. They will explore questions such as: what gases might be present in the atmosphere of an exoplanet, and how might they affect the appearance of the sky? How might the presence of multiple stars in a planetary system impact the sky's appearance? And what implications might these findings have for the search for life beyond our solar system? The panel will also discuss the imaginative ways that artists and writers have depicted alien skies in popular culture, from the twin sunsets of Tatooine to the red, dusty sky of Mars in The Martian. They will explore how these depictions have influenced public perceptions of alien words, bridging the gap between science and the imagination.

Elisa Victoria Quintana↗
NASA NTRS1974

Astronomy satellites in the U.S. program

The Orbiting Astronomical Observatory (OAO) series demonstrated that necessary thermal control systems and high pointing stability are feasible on astronomical satellites. A geosynchronous International Ultraviolet Explorer (IUE) is being planned by the US, UK, and ESRO for stellar spectroscopy. High Energy Astronomy Observatories, HEAO-A B, and C, will concentrate on stellar X-ray objects, cosmic ray physics, and gamma ray astronomy. A Shuttle-compatible Solar Maximum Mission (SMM) is planned for studying solar flares and flare related phenomena during the next solar maximum. Now in the instrumentation definition stage is the Large Space Telescope (LST), to provide higher resolution and sensitivity, larger wavelength range (from ultraviolet to far infrared), and higher time resolution than ground-based telescopes.

Aucremanne, M. J.↗
NASA NTRS2021

Discovery of an Extremely Short Duration Flare from Proxima Centauri Using Millimeter through Far-ultraviolet Observations

We present the discovery of an extreme flaring event from Proxima Cen by the Australian Square Kilometre Array Pathfinder(ASKAP), Atacama Large Millimeter/submillimeter Array(ALMA), Hubble Space Telescope(HST),Transiting Exoplanet Survey Satellite(TESS), and the du Pont Telescope that occurred on 2019 May 1. In the millimeter and FUV, this flare is the brightest ever detected, brightening by a factor of>1000 and>14,000 as seen by ALMA and HST, respectively. The millimeter and FUV continuum emission trace each other closely during the flare, suggesting that millimeter emission could serve as a proxy for FUV emission from stellar flares and become a powerful new tool to constrain the high-energy radiation environment of exoplanets. Surprisingly, optical emission associated with the event peaks at a much lower level with a time delay. The initial burst has an extremely short duration, lasting for<10 s. Taken together with the growing sample of millimeter M dwarf flares, this event suggests that millimeter emission is actually common during stellar flares and often originates from short burst-like events.

Stellar activity↗
NASA NTRS1985

On stellar X-ray emission

Stellar X-ray astronomy represents an entirely new astronomical discipline which has emerged during the past five years. It lies at the crossroads of solar physics, stellar physics, and general astrophysics. The present review is concerned with the main physical problems which arise in connection with a study of the stellar X-ray data. A central issue is the extent to which the extrapolation from solar physics is justified and the definition (if possible) of the limits to such extrapolation. The observational properties of X-ray emission from stars are considered along with the solar analogy and the modeling of X-ray emission from late-type stars, the modeling of X-ray emission from early-type stars, the physics of stellar X-ray emission, stellar X-ray emission in the more general astrophysical context, and future prospects.

Rosner, R.↗
NASA NTRS1974

Design of an X-ray telescope system for an orbiting astronomical observatory

The design and construction is described of a package of X-ray telescopes launched in the NASA satellite Copernicus (OAO-3), which began stellar observations in September 1972. It contains three grazing incidence reflectors covering a range of wavelengths from 0.3 to 8 nm, and having a combined collecting area of 40.9 sq cm, with angular resolutions up to 1 minute of arc. This is believed to be the first satellite application of such reflectors in stellar X-ray astronomy. A collimated detector of wavelengths 0.1-0.3 nm has a 17.8 sq cm collecting area. A visible light star tracker detects package misalignment if this should occur.

Bowles, J. A.↗
NASA NTRS1979

Scientific Research with the Space Telescope: International Astronomical Union Colloquium No. 54

The application of the space telescope for extragalactic astronomy, planetary research, and stellar, interstellar, and galactic structural problems is discussed. Topics include investigations of small solar system objects, the physical characteristics of ionized gaseous nebulae, the central regions of active galaxies and quasars, problems of cosmology, and the distribution and composition of interstellar matter.

Longair, M. S.↗
NASA NTRS1972

Research review, 1 January - 31 December 1972

Space science projects are reported individually for the period January 1, 1972 through December 31, 1972. The articles, representing both theoretical and experimental study approaches, present highlights of the research, along with graphical diagrams of important results. Subjects range from laboratory astrophysics to balloon-borne infrared astronomy, from lunar studies to stellar evolution, and from planetary atmospheric investigations to climatology. Applications of research for the same period are also reviewed, along with their attendant results.

Source record↗
NASA NTRS1993

Heavy element abundances and massive star formation

The determination of the stellar initial mass function (IMF) remains a great challenge in astronomy. In the solar neighborhood, the IMF is reasonable well determined for stellar masses from about 0.1 to 60 solar mass. However, outside the solar neighborhood, the IMF is poorly known. Among those frequently discussed arguments favoring a different IMF outside the solar neighborhood are the estimated time to consume the remaining gas in spiral galaxies, and the high rate of forming massive stars in starburst galaxies. An interesting question then is whether there may be an independent way of testing possible variations in the IMF. Indeed, the heavy elements in the interstellar medium are mostly synthesized in massive stars, so increasing, or decreasing, the fraction of massive stars naturally leads to a variation in the heavy element yield, and thus, the metallicity. The observed abundance should severely constrain any deviations of the IMF from the locally determined IMF. We focus on element oxygen, which is the most abundant heavy element in the interstellar medium. Oxygen is ejected only by massive stars that can become Type 1 supernovae, and the oxygen abundance is, therefore, a sensitive function of the fraction of massive stars in the IMF. Adopting oxygen enables us to avoid uncertainties in Type 1 supernovae. We use the nucleosynthesis results to calculate the oxygen yield for given IMF. We then calculate the oxygen abundance in the interstellar medium assuming instantaneous recycling of oxygen.

Wang, Boqi↗