Engineering Papers⌕ Search

Engineering topics

Mccluskey, G. E.

Publications and source records attributed to Mccluskey, G. E..

16 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Optically-thick, highly-variable plasma in interacting binaries

The interacting binaries HD 207739 and R Arae were observed by IUE. The ultraviolet spectrum of HD 207739 undergoes complex variations in both the lines and the continuum. Considerable circumstellar matter is present; R Arae (B9p + ?) exhibits SiIV, CIV and even NV absorption features. Both the lines and continuum are variable. An unusual secondary eclipse which is deeper in the ultraviolet than in the visible is present near phase 0.6. The CII line has a P cygni profile with emission present at all observed phases. These systems are probably in a relatively short-lived phase of evolution which is not often observed.

Kondo, Y.↗
NASA NTRS1984

Variable, optically thick, hot plasma observed in interacting binaries

Recent International Ultraviolet Explorer (IUE) observations of two interacting binaries, R Arae and HD 207739 are reported. The ultraviolet spectra indicate the presence of optically-thick, variable hot plasma in those binary systems. These two binaries may belong to a class of binaries that are currently undergoing a rarely observed and probably short-lived phase in their evolution. Their properties are compared with those of two other interacting binaries, U Cephei and Beta Lyrae.

Kondo, Y.↗
NASA NTRS1983

International Ultraviolet Explorer observations of the peculiar variable spectrum of the eclipsing binary R Arae

The eclipsing binary system R Arae = HD 149730 is a relatively bright southern system with an orbital period of about 4.4 days. It is a single-lined spectroscopic binary. The spectral class of the primary component is B9 Vp. The system was included in a study of mass flow and evolution in close binary systems using the International Ultraviolet Explorer satellite (IUE). Four spectra in the wavelength range from 1150 to 1900 A were obtained with the far-ultraviolet SWP camera, and six spectra in the range from 1900 to 3200 range were obtained with the mid-ultraviolet LWR camera. The close binary R Arae exhibits very unusual ultraviolet spectra. It appears that no other close binary system, observed with any of the orbiting satellites, shows outside-eclipse ultraviolet continuum flux variations of this nature.

Mccluskey, G. E.↗
NASA NTRS1982

The early-type component in v1 Sagittarii

Four low-resolution UV spectra of v1 Sgr (cK2) were obtained with the IUE satellite to investigate the nature of the hot component in this object, which was detected in the Astronomical Netherlands Satellite UV photometric data. The IUE results show that the spectral energy distribution of v1 Sgr in the FUV is comparable to that of a B9 star. FUV flux level, when compared with that of the mid-ultraviolet flux level, indicates that the luminosity of the hot component is roughly equivalent to that of a main-sequence star, assuming that the mid-ultraviolet flux is dominated almost entirely by a K2 I object. No discernible spectral features are present in the FUV, contrary to what may be expected in a star of B9 spectral type. Two possible interpretations are suggested: the hot component is a rapidly rotating star, or an accretion disk surrounding a central object which could be a collapsed star is being observed.

Kondo, Y.↗
NASA NTRS1982

The very unusual ultraviolet spectra of R Arae

The high resolution ultraviolet spectra of the 4.4-day period binary R Arae, observed in 1980 with the International Ultraviolet Explorer, show that its continuum flux level varied outside the eclipse by more than a factor of two in ten days, and by over 50 percent within the same orbital cycle. The flux level varied nonmonotonically at different wavelengths. The resonance lines of Mg II and Si IV exhibited shortward-shifted absorption components near phase 0.4, indicating the presence of a gas stream toward the observer at a velocity of some -450 to -500 km/s. The observations of R Arae with the Einstein satellite show it to be an X-ray source.

Kondo, Y.↗
NASA NTRS1981

Five-color band ultraviolet photometry of fourteen close binaries

Photometric observations obtained with the Astronomical Netherlands Satellite in five ultraviolet wavelength regions for 14 close binaries are presented. Strong excess far-ultraviolet flux is detected in four objects. The binaries TT Hya, RX Cas, and SX Cas exhibit a pronounced excess of far-ultraviolet flux, which is thought to be the result of mass transfer phenomena in these systems. Observations of the binary R Ara show very peculair variations; its far ultraviolet flux at 1550 A brightened by 0.4 mag between phases 0.7 and 0.8, while its near ultraviolet flux at 3300 A decreased by 0.5 mag over this same half-day interval. The A0 II-III component in the system RZ Sct is seen to dominate the ultraviolet spectrum.

Kondo, Y.↗
NASA NTRS1981

The ultraviolet spectrum of the O-type subdwarf HD 49798

The O-type subdwarf (O6p) single-lined spectroscopic binary HD 49798, with an orbital period of 1.5477 d, has been observed by the International Ultraviolet Explorer satellite, to aid in analyses of O type photospheres. Four high resolution (0.1A) spectra are found in the far-ultraviolet region, and two high resolution (0.2A) spectra are found in the mid-ultraviolet region. Numerous absorption lines are identified in the spectra of the star, most of which are attributable to Fe V lines at wavelengths of 1270 to 1500 A. Fe IV lines are also identified at wavelengths of 1500 to 1860 A. The strong Fe V features are found to have no corresponding analogs in the Kurucz and Peytremann (1975) list, and the total line blanketing for stars of spectral type O6 to B0 is discovered to be underestimated by at least a factor of four. In addition, mass loss from the subdwarf observed in the N V resonance doublet at wavelengths of 1238 A and 1242 A is discussed, indicating the existence of a hot stellar wind.

Bruhweiler, F. C.↗
NASA NTRS1981

IUE observations of mass ejection by the close binary system AO Cassiopeiae

It is noted that 11 high-resolution spectra in the far-ultraviolet and two high-resolution spectra in the mid-ultraviolet were obtained. A high-velocity stellar wind exists as indicated by narrow shortward-displaced absorption features superposed on the P Cygni lines of N V, Si IV, and C IV. Absorption lines caused by N IV and C III are present and show nonorbital velocities of about -50 to -150 km/sec. Several weak photospheric lines of the primary star are detected. A few lines of Fe IV and Fe V are detectable near phase 0.50 and, less prominently, near phase 0.00. It is noted that the He II absorption line appears doubled except near phases 0.00 and 0.50 and that the weaker component appears to be attributable to the secondary component of the system. The mean velocity of the stellar wind is -1879 + or - 51(p.e.) km/sec and is nearly constant over the period of observation, although the absorption strength is found to vary.

Mccluskey, G. E.↗
NASA NTRS1980

X-ray and ultraviolet spectroscopy of Cygnus X-1 = HDE 226868

Observations of Cygnus X-1 with the solid-state spectrometer on the Einstein Observatory are presented. The X-ray spectra of two intensity dips viewed near superior conjunction did not exhibit increased photoelectric absorption. Rather, the data support a model in which an increase in the electron-scattering optical depth modifies both the observed spectrum and the intensity. The characteristic temperature of the intervening material is greater than about 50 million K. These measurements were in part simultaneous with observations by IUE. The ultraviolet spectrum and intensity remained relatively constant during an X-ray intensity dip.

Pravdo, S. H.↗
NASA NTRS1980

Interstellar C IV and Si IV column densities toward early-type stars

Equivalent widths and deduced column densities of Si IV and C IV are examined for 18 early-type close binaries, and physical processes responsible for the origin of these ions in the interstellar medium are investigated. The available C IV/Si IV column density ratios typically lie within a narrow range from 0.8 to 4.5, and there is evidence that the column density of C IV is higher than that of N V along most lines of sight, suggesting that C IV is not formed in the same hot region as O VI. In addition, the existence of regions with a narrowly defined new temperature range around 50,000 deg K is indicated. The detection of the semitorrid gas of Bruhweiler, Kondo, and McCluskey (1978, 1979) is substantiated, and the relation of this gas to the observations of coronal gas in the galactic halo is discussed.

Bruhweiler, F. C.↗
NASA NTRS1979

Mass flow in close binaries - Results of optical and ultraviolet observations

Observational data provide information regarding mass flow in close binaries. Data about origin, condition, and development of circumstellar matter can also be obtained. The investigations are based on an evaluation and correlation of photometric observations and simultaneously made photoelectric and spectrographic observations in the visible spectral range and, in addition, also on satellite observations in the ultraviolet range. Supplementary information concerning the mass flow in close binaries is obtained on the basis of observations related to the X-ray, infrared, and radio range. Suitable theoretical models are employed to interpret the observational data.

Rahe, J.↗
NASA NTRS1976

Skylab ultraviolet stellar spectra - Emission lines from the Beta Lyrae system

Observations of Beta Lyr with the Skylab S-019 ultraviolet objective-prism spectrograph show numerous emission lines in the region from 1400 to 2300 A. Some variations in line strength between phases 0.25 and 0.50 are seen, which probably explain the shallowness of the OAO-2 light curve at 1910 A. Many of the emission lines are probably due to intercombination transitions, thus confirming the concept that the emission is produced by collisional excitation in low-density clouds of hot gas.

Kondo, Y.↗
NASA NTRS1976

Ultraviolet photometry from the Orbiting Astronomical Observatory. XXII Ultraviolet light variation of Beta Lyrae

Six-color ultraviolet light curves of the complex eclipsing binary system Beta Lyr were obtained with the OAO-2 Wisconsin Experiment Package. The filters had a typical width at half maximum of 150 to 200 A and were centered at 1430, 1550, 1910, 2460, 2980, and 3320 A. The most striking characteristics of the ultraviolet light curves are that the secondary minimum deepens at shorter wavelengths. This indicates that we are not observing the eclipse effect of two stars having roughly a Planckian distribution of energy. In combination with the high-resolution far-ultraviolet spectra of Beta Lyr recently obtained with Copernicus (OAO-3) Princeton Telescope Spectrometer, it is concluded that the far-ultraviolet light curves are dominated by emission from the high-temperature gas surrounding the binary system. The ultraviolet observations of OAO-2 and Copernicus are consistent with a model in which the enigmatic secondary component involves a gravitationally collapsed object; i.e., a black hole. However, alternative models are also admissible.

Kondo, Y.↗
NASA NTRS1976

Mass flow in close binary systems

The manner of mass flow in close binary systems is examined with a special view to the role of the so-called critical Roche (or Jacobian) lobe, taking into consideration relevant physical conditions such as radiation pressure that may affect the restricted three-body problem treatment. The mass does not necessarily flow from component one to component two through the L1 point to form a gaseous ring surrounding the latter. These considerations are applied to X-ray binaries with early-type optical components, such as Cyg X-1 (HDE 226868) and 3U 1700 - 37 (HD 153919). In the two bright close binary systems Beta Lyr and UW CMa, which are believed to be undergoing dynamic mass transfer, recent Copernicus observations show that the gas giving rise to the prominent ultraviolet emission lines surrounds the entire binary system rather than merely component two. Implications of these observations are also discussed.

Kondo, Y.↗
NASA NTRS1974

Copernicus spectra of beta Lyrae

The observations reported were made in August and September 1973. The principal data were scans in the low resolution mode at phases nearly coincident with the two light minima. Shorter scans were obtained at the two quadrature phases. The data show that the secondary component of beta Lyrae is a hotter object than the visible B8 star. The velocity amplitude of the lines suggests that the secondary is the more massive object, by a factor of several times.

Hack, M.↗