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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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NASA NTRS1989

X-ray spectroscopy of the ultrasoft transient 4U 1543 - 47

The X-ray transient 4U 1543 - 47 was observed in August 1983 by the Exosat observatory near the maximum of an outburst. The X-ray spectrum was measured using a gas scintillation proportional counter (GSPC) and a transmission grating spectrometer (TGS). A broad (FWHM about 2.7 keV) line at 5.9 keV is detected in the GSPC, which is interpreted as a redshifted and broadened iron K-alpha line. The line broadening and redshift may arise from either Compton scattering in a cool plasma with small optical depth and/or from Droppler and relativistic effects in the vicinity of compact object. The spectrum below 2 keV, obtained with the TGS, shows evidence for a broad emission feature at 0.74 keV, which may be an iron L-transition complex. However, such an emission feature could be an artifact caused by an anomalously low interstellar absorption by neutral oxygen. The contimuum emission is extremely soft and is well described by an unsaturated Comptonized spectrum from very cool plasma (kT = 0.84 keV) with large scattering depth.

Van Der Woerd, H.↗

NASA NTRS2020

The Origins Space Telescope Integration and Testing

This paper describes the plans, flows, key facilities, test beds, pathfinders, simulators and ground support equipment that could be used to fully integrate, functionally test and qualify the Origins Space Telescope (Origins). The Origins Observatory consists of the Spacecraft Bus Module (SBM) and the Cryogenic Payload Module (CPM), which comprises the telescope and three science instruments. The telescope is a Three Mirror Anastigmat (TMA) and is composed of four mirrors: three with optical power (the elliptical primary, hyperbolic secondary, and elliptical tertiary mirrors) and a flat field-steering mirror (FSM). The three science instruments spanning the wavelength range 2.8 to 588 μm provide the powerful new spectroscopic and imaging capabilities required to achieve the scientific objectives. The Origins Survey Spectrometer (OSS) uses six gratings in parallel to take multi-beam spectra simultaneously across the 25 to 588 μm window through long slits enabling deep 3D extra-galactic surveys. The Far-IR Imager/Polarimeter (FIP) provides imaging and polarimetric measurement capabilities at 50 and 250 μm. Its fast mapping enables rapid follow-up of transient or variable sources and efficient monitoring campaigns. The Mid-Infrared Spectrometer (MISC-T) provides spectroscopy simultaneously over 2.8 to 20 μm with exquisite stability and precision (<5 ppm between 2.8 to 10 μm, <20 ppm between 11 to 20 μm). All the instruments are delivered for Integration and Test fully qualified and calibrated. The Integration and Test program implemented at each level of assembly is discussed as well as the separation of thermal vacuum testing between the hot and cold zones of the Observatory. Portions of this manuscript appear in the Origins Study Final Report.

Origins↗

NASA NTRS2012

An Extreme X-ray Disk Wind in the Black Hole Candidate IGR J17091-3624

Chandra spectroscopy of transient stellar-mass black holes in outburst has clearly revealed accretion disk winds in soft, disk-dominated states, in apparent anti-correlation with relativistic jets in low/hard states. These disk winds are observed to be highly ionized. dense. and to have typical velocities of approx 1000 km/s or less projected along our line of sight. Here. we present an analysis of two Chandra High Energy Transmission Grating spectra of the Galactic black hole candidate IGR J17091-3624 and contemporaneous EVLA radio observations. obtained in 2011. The second Chandra observation reveals an absorption line at 6.91+/-0.01 keV; associating this line with He-like Fe XXV requires a blue-shift of 9300(+500/-400) km/ s (0.03c. or the escape velocity at 1000 R(sub schw)). This projected outflow velocity is an order of magnitude higher than has previously been observed in stellar-mass black holes, and is broadly consistent with some of the fastest winds detected in active galactic nuclei. A potential feature at 7.32 keV, if due to Fe XXVI, would imply a velocity of approx 14600 km/s (0.05c), but this putative feature is marginal. Photoionization modeling suggests that the accretion disk wind in IGR J17091-3624 may originate within 43,300 Schwarzschild radii of the black hole, and may be expelling more gas than accretes. The contemporaneous EVLA observations strongly indicate that jet activity was indeed quenched at the time of our Chandra observations. We discuss the results in the context of disk winds, jets, and basic accretion disk physics in accreting black hole systems

King, A. L.↗

NASA NTRS1997

A Three-Year Program of Micro- and Nano-System Technology Development for X-Ray Astronomy

For many years the work at MIT aimed at the development of new concepts and technologies for space experiments in high-energy astrophysics, but not explicitly supported by flight programs, has been supported. This work has yielded new devices and techniques for X-ray astronomy, primarily low-noise, deep-depletion charge-coupled devices (CCDS) for spectrally-resolved X-ray imaging, and high-performance transmission gratings for high-resolution X-ray spectroscopy. Among the most significant recent achievements have been the development by G. Ricker and associates of the X-ray CCD camera flying on ASCA, and currently in development for AXAF and Astro-E, and the development by C. Canizares and associates of thick, 200 nm-period transmission gratings employing the phenomenon of phase shifting for high-resolution X-ray spectroscopy up to energies of 8- 1 0 keV that is essential for the operation of the AXAF High Energy Transmission Grating Spectrometer (HETGS). Through the current SR&T grant, the latter technology is now being extended successfully to the fabrication of 100 nm-period transmission gratings, which have twice the dispersion of the AXAF gratings. We note that, among other outcomes, the modest investments of past SR&T Grants at MIT resulted in the development of the key technologies for fully one-half of the scientific instrumentation on AXAF. In addition, NASA flight programs that have benefited from previous SR&T support at MIT include the SAS 3 X-ray Observatory, which carried the first rotation modulation collimator, the Focal Plane Crystal Spectrometer (FPCS) on the Einstein Observatory, the CCD cameras on ASCA and planned for Astro-E, the High Energy Transient Experiment (HETE), the Solar EUV Monitor on the Solar and Heliospheric Observatory (SOHO), the Medium Energy Neutral Atom imager (MENA) on the Image for Magnetopause-to-aurora Global Exploration (IMAGE) mission, and the recently-approved Two Wide-Angle Imaging Neutral-atom Spectrometers (TWINS) Mission of Opportunity.

Canizares, Claude R.↗