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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Simultaneous Exosat and VLA observations of the W UMa binaries, VW Cep and XY Leo - A flare on VW Cep

Two UMa-type contact binaries, XY Leo and VW Cep, have been observed simultaneously with Exosat, the VLA, and, in the case of XY Leo, optically. The temporal coverage of each star was sufficient to monitor them throughout two orbital revolutions (P about 0.25 days), however, no orbital modulation of either the X-ray or 6-cm data was seen for either star. A large flare from VW Cep was detected, the first such simultaneous flare ever seen on a star other than the sun. Its behavior before, during, and after the flare is remarkably similar to that found in solar flares. For both stars, it is demonstrated that the 6-cm emission cannot be the result of bremsstrahlung radiation of the X-ray emitting plasma.

Vilhu, Osmi↗
NASA NTRS1986

H and K maps of two star-forming regions: S 140 and CEP A OB3

The molecular clouds near S 140 and Cep A OB3 both contain regions that emit strongly in the infrared but which have relatively little or no emission in radio wavelengths. The lack of radio emission is usually interpreted to mean that little ionization has taken place, and that the IR emission comes from dust heated by a central pre-main sequence object. We have made high resolution maps of these two areas with H and K broadband filters with the 2.3m telescope of the Wyoming Infrared Observatory (WIRO). Our observations were made with an InSb detector using the standard WIRO mapping technique of multiple scanning to construct a series of 64x64 pictures. Our scanning was made in one arcsec steps with a 7 inch aperture to produce a resolution of about 6 sec FWHM. Observations of S 140 by Blair et al (1978) with moderate resolution in J, H, and K, revealed a prominent IR source that they called S 140IR. We have scanned an area surrounding their S 140IR region and have obtained total IR fluxes which are in close agreement with Blair et al. Additional detail corresponds to that seen by Dinerstein et al (1979) at 0.9 microns and Campbell (1986) at 1.0 microns. The large (H-K) values for all components of S 140IR indicates that they are probably embedded in the parent molecular cloud with A(v) = 25 mag and A(K) = 2.2 mag. Recent radio studies of Cep A by Hughes and Wouterloot (1984) and FIR studies by Evans et al (1981) have shown the similarity of Cep A to S 140. There is, however, some emission detected from ionized regions by the radio observations, indicating a slightly more advanced stage of evolution for Cep A. We observed an area around the strongest source in Cep A in both H and K, and the K map is presented. We have identified three sources separate from the main source.

Graadalen, G. L.↗
NASA NTRS1989

Properties of interstellar dust in the region of the CEP OB4 association

Regional variations in the interstellar extinction law was examined. The region of Cyg was noted among the areas with abnormal interstellar extinction law (IEL). An attempt was made to study interstellar extinction in the region of the Cep OB4 association. The Vilnius seven color photometric system was used for this purpose. The effective wavelengths and their reciprocals for the Vilnius photometric system are presented. This system was applied for the study of variations in the IEL in four regions of the sky: Cyg, Cep, Per, and Mon (Sudzius, 1974). The results of multicolor photometry were combined with the data of Whiteoak (1966) and detailed interstellar extinction curves were derived for Cyg and for Cep-Per-Mon (average) regions in the wavelengths interval of 3000 to 8000 A (Sudzius, 1974). The obtained IEL for the Cep OB4 association does not match any of the laws determined for other regions of the sky. However, it is very close to Cyg OB2 law in the ultraviolet. Results suggest that Cep OB4 IEL have no very broadband structure (VBS) in the interval of wavenumbers 1.84 to 2.15/micron.

Sudzius, J.↗
NASA NTRS1998

Recent Outbursts from the Transient X-Ray Pulsar Cep X-4 (GS 2138+56)

We report on X-ray observations of the 66 s period transient X-ray pulsar Cep X-4 (GS 2138+56) with the Burst and Transient Source Experiment (BATSE) on the Compton Gamma-Ray Observatory (CGRO) and with the Rossi X-ray Timing Explorer (RXTE). Two outbursts from Cep X-4 were observed with BATSE in 1993 June-July and 1997 July. Spin periods of P(sub spin) = 66.2510 +/- 0.0009 s on 1993 June 25 (MJD 49,163) and P(sub spin) = 66.27 68 +/- 0.0007 s on 1997- July 12 (MJD 50,641) were each measured from 2 day spans of BATSE data near each outburst's peak. Cep X-4 showed an average spin down rate of P/P = (8.7 +/- 0.2) x 10(exp -5)/ yr between the 1993 and 1997 outbursts. After BATSE could no longer detect Cep X-4, public observations were performed on 1997 July 18 & 25 with the Proportional Counter Array (PCA) on RXTE. A spin period Of P(sub spin) = 66.28 +/- 0.02 s was measured from observations on 1997 July 18 (MJD 50,647). Significant aperiodic noise, with an rms variance of approx. 18% in the frequency range 0.01 - 1.0 Hz was observed on both days. Energy and intensity dependent pulse shape variations were also seen in these data. Recently published optical observations associate Cep X-4 with a Be companion star.

Wilson, Colleen A.↗
DOE OSTI2025

High-repetition rate, CEP-stable shortwave infrared source with two-cycle pulses for field-resolved spectroscopy

We report on a passively carrier-envelope phase (CEP)-stable optical parametric amplifier generating two-cycle pulses at 2060 nm with energies of up to 2.25 µJ operating at a repetition rate of 400 kHz, specifically designed for applications in field-resolved spectroscopy. The measured pulse duration is 13.6 fs, resulting in two cycles of the carrier wave. Due to the robust CEP-stable front-end design, we achieve an open-loop CEP stability of 250 mrad (rms) and the capability for fast CEP modulation.

47 OTHER INSTRUMENTATION↗
NASA NTRS1983

The morphology and kinematics of the Cep IV star formation region

Rossano et al. (1980) have discussed the morphology and kinematics of Cep IV star formation region. The present investigation is concerned with H2CO observations which have been conducted to examine the relationship between the neutral and ionized gas in the Cep IV star formation region and to study the origin of the unusual kinematics and morphology of the stars, gas, and dust in this region. Six-cm H2CO observations were undertaken throughout a one half degree square area centered on the H II region W1. In addition, VLA observations of the Cep IV region at 6 and 20 cm were also performed. The neutral gas in the vicinity of W1 is found to be located in clouds having velocities of -13, -7, and 1 km/s. The gas at - 7 km/s appears to be undisturbed gas from the original dark cloud complex.

Grayzeck, E. J.↗
NASA NTRS1980

A continuum and recombination line study of the Cep IV star formation region

The Cep IV star formation region consists of the Cep IV OB association, the H II regions W 1 and NGC 7822, and an extensive fragmented dust cloud complex. Six- and nine-cm radio continuum observations and 6-cm hydrogen recombination line observations show that all of the emission nebulosity in this region, which includes a large loop-type structure suggested by Herbst and Assousa (1977) to be a supernova remnant, has a thermal spectrum. The two components of W 1 have been detected at H 110 alpha and are found to be kinematically distinct.

Rosano, G. S.↗
NASA NTRS1997

Outbursts from the Transient X-Ray Pulsar Cep X-4 (GS 2138+56)

Cep X-4 was discovered with the Orbiting Solar Observatory (OSO) 7 Satellite in 1973 June-July, but no pulsations were detected. In March 1988, an additional outburst was observed with Gingaq. Pulsations at a period of 66.2490 +/- .0001 s were detected during a month long outburst which peaked at about 100 mCrab (1-20 keV) in early April 1988. The source apparently did not appear again until June 1993 when it was detected by Roentgen Satellite (ROSAT) and Burst and Transient Source Experiment (BATSE). Pulsations at a period of 66.2499 +/- .0007 s were detected by BATSE. The outburst lasted about two weeks and had a peak pulsed flux of 15-20 mCrab (20-50 keV). In July 1997, BATSE and the All-Sky Monitor (ASM) on Rossi X-ray Timing Explorer (RXTE) observed a new outburst from Cep X-4. Pulsations at a period of 66.2743 +/- 0.0005 s were detected by BATSE. This outburst lasted about 2 weeks and peaked at a pulsed flux of about 10-15 mCrab (20-50 keV). Results of a search of BATSE data for additional outbursts will be presented. Pulse frequency and flux histories will be presented and compared to the flux history from the RXTE ASM. Implications of the apparent spin-down between outbursts will be discussed.

Wilson, Colleen A.↗
NASA NTRS1981

Notes on the early-type components of W Cep, o Cet, CH Cyg, AR Mon, and BL Tel

Low resolution IUE spectra in both spectral regions are used to clarify the nature of the warmer components of several binary systems. The W Cep, the primary of which is a luminous K-type supergiant, shows an ultraviolet absorption spectrum of type B0 or B1; this system is heavily reddened. The hot companion of Mira (o Cet) is surprisingly faint in the short wavelength region, but it excites a rich emission spectrum from the surrounding gas. The ultraviolet active M7 giant CH Cyg is shown to be a binary with a hot companion. This system was also observed at high resolution and shows variable Fe II emission and well-separated circumstellar and interstellar absorptions within the broad Mg II emission profiles. The eclipsing binaries AR Mon and BL Tel are shown not to have hot companions.

Wing, R. F.↗
NASA NTRS1987

Calculating the CEP (Circular Error Probable)

This report compares the probability contained in the Circular Error Probable associated with an Elliptical Error Probable to that of the EEP at a given confidence level. The levels examined are 50 percent and 95 percent. The CEP is found to be both more conservative and less conservative than the associated EEP, depending on the eccentricity of the ellipse. The formulas used are derived in the appendix.

Source record↗
NASA NTRS2003

Doppler Imaging with FUSE: The Partially Eclipsing Binary VW Cep

This report covers the FUSE Guest Observer program. This project involves the study of emission line profiles for the partially eclipsing, rapidly rotating binary system VW Cep. Active regions on the surface of the star(s) produce observable line shifts as the stars move with respect to the observer. By studying the time-dependence of the line profile changes and centroid shifts, one can determine the location of the activity. FUSE spectra were obtained by the P.I. 27 Sept 2002 and data reduction is in progress. Since we are interested in line profile analysis, we are now investigating the wavelength scale calibration in some detail. We have also obtained and are analyzing Chandra data in order to compare the X-ray velocities with the FUV velocities. A complementary project comparing X-ray and Far UltraViolet (FUV) emission for the similar system 44i Boo is also underway. Postdoctoral fellow Ronnie Hoogerwerf has joined the investigation team and will perform the data analysis, once the calibration is optimized.

Sonneborn, George↗
NASA NTRS2006

Disk Evolution in Cep OB2: Results from the Spitzer Space Telescope

We presented the results of an infrared imaging survey of Tr 37 and NGC 7160 using the IRAC and MIPS instruments on board the Spitzer Space Telescope. Our observations cover the wavelength range from 3.6 to 24 microns, allowing us to detect disk emission over a typical range of radii 0.1 to 20 AU from the central star. In Tr 37, with an age of about 4 Myr, about 48% of the low-mass stars exhibit detectable disk emission in the IRAC bands. Roughly 10% of the stars with disks may be "transition" objects, with essentially photospheric fluxes at wavelengths i 4.5 microns but with excesses at longer wavelengths, indicating an optically thin inner disk. The median optically thick disk emission in Tr 37 is lower than the corresponding median for stars in the younger Taurus region; the decrease in infrared excess is larger at 6-8 microns than at 24 microns, suggesting that grain growth and/or dust settling has proceeded faster at smaller disk radii, as expected on general theoretical grounds. Only about 4% of the low-mass stars in the 10 Myr old cluster NGC 7160 show detectable infrared disk emission. We also find evidence for 24 micron excesses around a few intermediate-mass stars, which may represent so-called "debris disk" systems. Our observations provided new constraints on disk evolution through an important age range.

Sicilia-Aguilar Aurora↗
NASA NTRSDate not supplied

CEPS - A Compact Electron-Proton Spectrometer

Small mass/power sensors are needed for autonomous Moon surface ops that provide alerts to impending adverse space weather conditions. In order to use current operational forecasting tools, a sensor capable of measuring both high-energy electrons and protons is needed. By combining high-TRL Timepix technology with a CdTe layer, this project leverages known technology to fill a critical gap for surface operations. The proposed work will bring ability to provide warnings to crews to shelter with a device that can easily be carried on the Lunar and Martian surfaces.

Radiation↗
NASA NTRS2022

A Compact Electron-Proton Spectrometer for Moon / Mars Surface Space Weather Monitoring and Crew Protection (CEPS)

Small mass/low-power sensors are needed for autonomous Moon/Mars surface ops that provide alerts to impending adverse space weather conditions. In order to use current operational forecasting tools, a sensor capable of measuring both high-energy electrons and protons is needed. By combining high-TRL Timepix technology with a CdTe layer, this project leverages known technology to fill a critical gap for surface operations. Typical space weather sensors are at least an order of magnitude higher in mass than is expected from Timepix-based devices and are deployed on robotic assets away from human crews. High fidelity measurements at the crew location and subsequent ability are needed to provide warnings to crews to shelter with a device that can easily be carried on the Lunar and Martian surfaces.​ The aim of this project is the development of compact, low power space weather sensors for crew protection based on the combination of AES flight heritage Timepix hardware with novel CdTe (Cadmium Telluride) sensors. CdTe technology has only recently matured to a point where it can be reliably used with Timepix detectors. These detectors will be able to measure electron spectra in an energy range relevant to the RELEASE model, which is used operationally by NASA to provide crew early warning of Solar Energetic Particle Events as well as protons in the energy ranges relevant to human health allowing for event ‘nowcasting’ and total event crew dose prediction. Compared to existing solutions these detectors will be compact enough to travel with crew, providing a significant advantage to space environment situation awareness. Project results indicate that CdTe-based Timepix sensors respond well to energetic electrons, and particle tracks are sufficiently distinct to be able to measure in a mixed radiation field. Thermal testing results point to a needed design modification to mitigate high temperatures the detector will see in space. Radiation susceptibility testing was conducted to assess the radiation hardness of the CdTe-Timepix assembly. Overall, the assembly continued to operate up to 100 kRad of gamma-ray exposure. The system calibration did show drift over time but recovered once exposure was complete.

Dan James Fry↗
NASA NTRS2023

CEPS – A Compact Electron-Proton Spectrometer

Small mass/low-power sensors are needed for autonomous Moon/Mars surface ops that provide alerts to impending adverse space weather conditions. In order to use current operational forecasting tools, a sensor capable of measuring both high-energy electrons and protons is needed. By combining high-TRL Timepix technology with a CdTe layer, this project leverages known technology to fill a critical gap for surface operations. Typical space weather sensors are at least an order of magnitude higher in mass than is expected from Timepix-based devices and are deployed on robotic assets away from human crews. High fidelity measurements at the crew location and subsequent ability are needed to provide warnings to crews to shelter with a device that can easily be carried on the Lunar and Martian surfaces.​ The aim of this project is the development of compact, low power space weather sensors for crew protection based on the combination of AES flight heritage Timepix hardware with novel CdTe (Cadmium Telluride) sensors. CdTe technology has only recently matured to a point where it can be reliably used with Timepix detectors. These detectors will be able to measure electron spectra in an energy range relevant to the RELEASE model, which is used operationally by NASA to provide crew early warning of Solar Energetic Particle Events as well as protons in the energy ranges relevant to human health allowing for event ‘nowcasting’ and total event crew dose prediction. Compared to existing solutions these detectors will be compact enough to travel with crew, providing a significant advantage to space environment situation awareness. Project results indicate that CdTe-based Timepix sensors respond well to energetic electrons, and particle tracks are sufficiently distinct to be able to measure in a mixed radiation field. Detector response functions were developed for both electrons and protons. Measurement results showed response to both electrons and protons in the energy range of interest for human space flight.

Radiation↗