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Results for “Soft X-ray Telescope”

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 55 records · Page 3
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NASA NTRS1975

Soft X-ray observations of Centaurus X-3 from Copernicus

We have detected soft X-ray emission from Centaurus X-3 in the 0.6-1.9 keV band, using the focusing telescope aboard OAO Copernicus. The flux is compatible with an extrapolation of the harder X-ray spectrum, attenuated by (3-4) times 10 to the 22nd atoms per sq cm of interstellar and/or circumstellar matter. The data are consistent with the distance estimate of 5-10 kpc derived from the spectroscopic modulus of the optical component, and obviate the need to postulate the primary to be an anomalously subluminous hot star. There is currently no compelling evidence that such models must be invoked to explain any of the observed compact X-ray sources.

Margon, B.↗
NASA NTRS1973

Ground-based flare studies at Sacramento Peak

The structure of an isolated solar flare point observed by vacuum telescope and multichannel spectrophotometer is considered. The tiny bright spot in H alpha photos lasted less than 30 seconds and coincided with a Type-III solar burst; a soft X-ray burst peaked at the time of this event. The small scale structure of the flare point exhibited in miniature the characteristics of a true flare event.

Maran, S. P.↗
NASA NTRS1979

Analysis of X-ray and EUV spectra of solar active regions

Data acquired by two flights of an array of six Bragg crystal spectrometers on an Aerobee rocket to obtain high spatial and spectral resolution observations of various coronal features at soft X-ray wavelengths (9-23A) were analyzed. The various aspects of the analysis of the X-ray data are described. These observations were coordinated with observations from the experiments on the Apollo Telescope Mount and the various data sets were related to one another. The Appendices contain the published results, abstracts of papers, computer code descriptions and preprints of papers, all produced as a result of this research project.

Strong, K. T.↗
NASA NTRS1977

A survey of soft X-ray limb flare images - The relation between their structure in the corona and other physical parameters

The data used in the investigation were obtained by the American Science and Engineering S-054 experiment on board Skylab. The instrument employed was a grazing incidence X-ray telescope which records images of the sun on film. The morphology of limb flares is investigated and the observed spatial structure is related with the other physical parameters of the region (temperature, density, characteristic times, and energy density). It is concluded that two physically distinct classes of flares exist that differ both in their morphology and in the physical properties which characterize the emitting regions.

Pallavicini, R.↗
NASA NTRS1978

Determination of the structure and heating mechanisms of coronal loops from soft X-ray observations with the solar probe

High resolution soft X-ray imaging from the solar probe is justified in terms of the expected scientific returns which include the determination of the temperature and density structure of a coronal loop. The advantages of the grazing incidence telescope over the multiple pinhole camera are discussed. An instrument package is described which includes a grazing incidence mirror, a thermal prefilter, a three position filter wheel and a focal plane detector baselined as an 800 by 800 back-illuminated charge coupled device. The structural assembly together with the data processing equipment would draw heavily on the designs being developed for the Solar Polar Mission.

Davis, J. M.↗
NASA NTRS1978

Upper limits on extreme ultraviolet radiation from nearby main sequence and subgiant stars

Flux upper limits for 44-800 A radiation were measured in a sample of nearby main sequence stars and one subgiant star with the aid of the Apollo-Soyuz grazing incidence telescope. Comparisons of emission measure upper limits with three different methods for predicting coronal properties cannot yet determine which, if any, are valid. Data for Alpha Centauri A and B are consistent with recent HEAO-1 soft X-ray measurements which suggest that the surface flux of coronal emission from the Alpha Cen system is comparable to that of the 'normal' sun.

Ayres, T. R.↗
NASA NTRS1976

Collimators for soft X-ray measurements

The development of X-ray grid collimators at the Los Alamos Scientific Laboratory is considered with attention given to grid design (patterns and artwork for masters, materials, layout of grid patterns), mounting techniques (index housings, L-bar and T-bar housings, U-housings, rectangular housings). Alignment techniques (adjustable frames and alignment telescope, adjustable frames and on-axis and off-axis telescopes) are considered along with test procedures (plane parallel X-ray beam, convolved response).

Blake, R. L.↗
NASA NTRS1976

Instrumentation for solar spectrophotometry at extreme ultraviolet and soft X-ray wavelengths

The solar extreme ultraviolet and soft X-ray (XUV) spectrum at wavelengths between 20 and 300 A contains a wealth of emission lines from ions formed at temperatures from 10 to the 5th K to greater than 2 x 10 to the 7th K. The requirements for high resolution spectrophotometric instrumentation are discussed in the light of data obtained with extreme ultraviolet and X-ray telescopes flown on Skylab. The design of a grazing-incidence spectroheliometer for active region and flare studies over the wavelength range from 40 to 630 A is presented and recently developed high-efficiency detectors and detector-arrays for use at XUV wavelengths are described.

Timothy, J. G.↗
NASA NTRS1977

The atmosphere of Sirius B. II - Extreme-ultraviolet observations

The letter reports an observation of Sirius in the extreme-ultraviolet (100-1000 A) band, using a grazing-incidence telescope flown aboard the Apollo-Soyuz mission. No positive flux is detected; under the arbitrary assumption of flat incident spectrum, an upper limit to the flux in the 170-620 A band is 5 billion erg/sq cm per sec. A detailed model-atmosphere analysis, when combined with the EUV limits, places severe constraints on models which attribute the previously reported soft X-ray (44-60 A) flux to thermal radiation from deep layers of the atmosphere of the white dwarf Sirius B. EUV radiation should be detectable from Sirius B just below the sensitivity threshold of the current data, or a thermal origin for the X-ray flux is untenable. If the X-ray flux is thermal, the present results provide extremely sensitive constraints on the temperature and helium abundance of Sirius B: the white dwarf has an effective temperature of 32,000 K to 32,500 K and a helium abundance (relative to hydrogen) of 0.0001 to 0.0002.

Shipman, H. L.↗
NASA NTRS1971

Long term temporal variations of the hard X-ray flux from the Centaurus region

The X-ray telescope aboard the third Orbiting Solar Observatory (OSO-3) observed the Centaurus region daily from 1967 October to 1968 February, and also for five days in 1968 June. A stable minimum flux of 0.33 + or - 0.03 photons (sq cm sec)/1 between 7.7 and 38 keV from a source around l = 305 deg is derived. Several single days show enhanced fluxes, and two extensive flaring episodes, one with a soft and the other a very hard spectrum, lasting at least ten days.

Schwartz, D. A.↗
DOE OSTI2025

Directly imaging the cooling flow in the Phoenix cluster

In the centres of many galaxy clusters, the hot (approximately 10 7 kelvin) intracluster medium can become dense enough that it should cool on short timescales. However, the low measured star formation rates in massive central galaxies and the absence of soft X-ray lines from the cooling gas suggest that most of this gas never cools. This is known as the cooling flow problem. The latest observations suggest that black hole jets are maintaining the vast majority of gas at high temperatures. A cooling flow has yet to be fully mapped through all the gas phases in any galaxy cluster. Here we present observations of the Phoenix cluster using the James Webb Space Telescope to map the [Ne vi] λ 7.652-μm emission line, enabling us to probe the gas at 10 5.5 kelvin on large scales. These data show extended [Ne vi] emission that is cospatial with the cooling peak in the intracluster medium, the coolest gas phases and the sites of active star formation. Taken together, these imply a recent episode of rapid cooling, causing a short-lived spike in the cooling rate, which we estimate to be 5,000–23,000 solar masses per year. As a result, these data provide a large-scale map of gas at temperatures between 10 5 kelvin and 10 6 kelvin in a cluster core, and highlight the critical role that black hole feedback has in not only regulating cooling but also promoting it.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1972

Long-term temporal variations of the hard X-ray flux from the Centaurus region.

An X-ray telescope aboard OSO 3 observed the Centaurus region daily from October 1967 to February 1968, and also for five days in June 1968. For this period, we derive a stable minimum flux of 0.33 plus or minus 0.33 photons per sq cm per sec between 7.7 and 38 keV from a persistent hard X-ray source around 305 deg longitude. Several single days show enhanced fluxes; and two extensive flaring episodes, one with a soft and the other with a very hard spectrum, last at least 10 days.

Schwartz, D. A.↗
DOE OSTI2025

Chandra Discovery of a Candidate Hyperluminous X-Ray Source in MCG+11-11-032

We present a multiwavelength analysis of MCG+11-11-032, a nearby active galactic nucleus (AGN), with a unique classification as being both a binary and a dual AGN candidate. With new Chandra observations, we aim to resolve any dual AGN system via imaging data and search for signs of a binary AGN via analysis of the X-ray spectrum. Analyzing the Chandra spectrum, we find no evidence of the previously suggested double-peaked Fe Kα lines; the spectrum is instead best fit by an absorbed power law with a single Fe Kα line, as well as an additional line centered at ≈7.5 keV. The Chandra observation reveals faint, soft, and extended X-ray emission, possibly linked to low-level nuclear outflows. Further analysis shows evidence for a compact hard source—MCG+11-11-032 X2—located 3.″3 from the primary AGN. Modeling MCG+11-11-032 X2 as a compact source, we find that it is relatively luminous (L2–10 keV=1.5−0.5+0.9×1041erg s$^{−1}$), and the location is coincident with a compact and off-nuclear source resolved in Hubble Space Telescope infrared (F105W) and optical (F621M, F547M) bands. Pairing our X-ray results with a 144 MHz radio detection at the host galaxy location, we observe X-ray and radio properties similar to those of ESO 243-49 HLX-1, suggesting that MCG+11-11-032 X2 may be a hyperluminous X-ray source. This detection with Chandra highlights the importance of a high-resolution X-ray imager as well as how previous binary AGN candidates detected with large-aperture instruments can benefit from high-resolution follow-up. Future spatially resolved optical spectra, and deeper X-ray observations, can better constrain the origin of MCG+11-11-032 X2.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1975

Interstellar absorption lines toward gamma Arae

The available data on interstellar absorption lines in the spectrum of gamma Ara observed from the ground and with the Copernicus telescope have been analyzed to give column densities of various ion stages of H, C, N, O, Na, Mg, Si, P, S, Ar, Ca, Mn, and Fe. The element abundances with respect to H nuclei in H I regions are similar to the values for zeta Oph, with depletions relative to the sun tending to increase with increasing condensation temperature. For example, toward gamma Ara, Fe is depleted by a factor of 50; Mg, Si, and Mn by about 10; and S, P, and N little or none. Interstellar Si IV and probably S IV appear stronger than in most other stars, but still their low ratios to Si III and S III suggest that soft X-rays and low-energy cosmic rays are not important sources of ionization. The width of the O VI lines and the absence of N V have been interpreted as evidence for a collisionally ionized region with a temperature between 300,000 and 700,000 K containing at least 0.0004 of the total interstellar column density.

Morton, D. C.↗
DOE OSTI2025

Delving into the depths of NGC 3783 with XRISM

The 2024 X-ray/UV observation campaign of NGC 3783, led by XRISM, revealed the launch of an ultrafast outflow (UFO) with a radial velocity of 0.19c (57 000 km s −1 ). This event is synchronized with the sharp decay, within less than half a day, of a prominent soft X-ray/UV flare. Accounting for the look-elsewhere effect, the XRISM Resolve data alone indicate a low probability of 2 × 10 −5 that this UFO detection is due to random chance. The UFO features narrow H-like and He-like Fe lines with a velocity dispersion of ∼1000 km s −1 , suggesting that it originates from a dense clump. Beyond this primary detection, there are hints of weaker outflow signatures throughout the rise and fall phases of the soft flare. Their velocities increase from 0.05c to 0.3c over approximately three days, and they may be associated with a larger stream in which the clump is embedded. The radiation pressure is insufficient to drive the acceleration of this rapidly evolving outflow. The observed evolution of the outflow kinematics instead closely resembles that of solar coronal mass ejections, implying magnetic driving and, conceivably, reconnection near the accretion disk as the likely mechanisms behind both the UFO launch and the associated soft flare.

Astronomy and AstroPhysics↗
DOE OSTI2025

Initial in-orbit operation of the soft X-ray spectrometer Resolve onboard the X-ray imaging and spectroscopy mission satellite

The X-Ray Imaging and Spectroscopy Mission satellite was launched on September 6, 2023 (UT). Its Resolve instrument is a high-resolution X-ray spectrometer enabled by a microcalorimeter array thermally anchored to a 50-mK heat sink. Many sensitive, critical sub-systems comprise Resolve, including a multistage cryogenic cooling system, thin-film aperture filters, low-noise electronics, on-board signal processing, and several sources of X-rays for calibration. We summarize the initial on-orbit power-on and checkout of Resolve that commenced immediately after launch. Soon after launch, the cryocoolers were activated, and their operation was successfully established. On October 9, 2023, the first cycle of the adiabatic demagnetization refrigerator was carried out, bringing the sensors to their steady-state operational temperatures. Following this, the energy resolution at 5.9 keV was successfully measured. The energy scale of the system is highly sensitive to the thermal environment surrounding both the sensors and their analog electronics. Gain correction was performed using reference X-ray lines from onboard calibration sources. To optimize cooler frequency settings, noise spectra were collected across a range of frequencies, and the most suitable frequency pair was selected based on the in-orbit environment. During the final phase of the checkout, an attempt was made to open the gate valve, which is designed to protect the Dewar’s interior from external pressure during ground operations and launch. Unfortunately, this attempt was unsuccessful. As a result, the checkout process was temporarily paused, and a stable operational strategy was subsequently developed to enable Resolve to function effectively with the gate valve remaining closed.

X-ray micro-calorimeter↗
DOE OSTI2025

GRB 221009A: The B.O.A.T. Burst that Shines in Gamma Rays

We present a complete analysis of Fermi Large Area Telescope (LAT) data of GRB 221009A, the brightest gamma-ray burst (GRB) ever detected. The burst emission above 30 MeV detected by the LAT preceded, by 1 s, the low-energy (<10 MeV) pulse that triggered the Fermi Gamma-Ray Burst Monitor (GBM), as has been observed in other GRBs. The prompt phase of GRB 221009A lasted a few hundred seconds. It was so bright that we identify a bad time interval of 64 s caused by the extremely high flux of hard X-rays and soft gamma rays, during which the event reconstruction efficiency was poor and the dead time fraction quite high. The late-time emission decayed as a power law, but the extrapolation of the late-time emission during the first 450 s suggests that the afterglow started during the prompt emission. We also found that high-energy events observed by the LAT are incompatible with synchrotron origin, and, during the prompt emission, are more likely related to an extra component identified as synchrotron self-Compton (SSC). A remarkable 400 GeV photon, detected by the LAT 33 ks after the GBM trigger and directionally consistent with the location of GRB 221009A, is hard to explain as a product of SSC or TeV electromagnetic cascades, and the process responsible for its origin is uncertain. Because of its proximity and energetic nature, GRB 221009A is an extremely rare event.

79 ASTRONOMY AND ASTROPHYSICS↗