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Kondo, Y.

Publications and source records attributed to Kondo, Y..

At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

The ultraviolet spectra of four binaries observed with the S59 spectrometer

Ultraviolet spectra of Omicron And, Alpha CrB, Eta Ori A, and Alpha Vir, which were obtained with the S59 spectrometer at a resolution of 1.7 A in three 100-A-wide regions centered at 2110, 2454, and 2825 A, have been studied for the presence or absence of effects due to their binary nature. As may have been anticipated from their orbital and other characteristics, no indication of strong binary interactions were seen in these observations. However, there are certain spectral peculiarities suggesting the possibility of modifications of spectral classifications for some of these objects. A rather unusual spectral behavior in Alpha Vir is also noted. In addition, based primarily on a review of available literature, attention is drawn to a remarkable property of the third component in Eta Ori A.

Herczeg, T. J.↗
NASA NTRS1977

The Mg II features near 2800A and spectral classification

Relatively high-resolution (about 0.4 A) observations of the Mg II resonance lines at 2795.523 and 2802.698 A as well as their respective subordinate lines at 2797.989 and 2790.768 A are discussed for main-sequence stars, giants, and supergiants. The general behavior of the Mg II lines as a function of spectral type is described. An expression is obtained for the relationship between absolute magnitude and Mg II emission widths. The variation of the absorption widths of the Mg II features with spectral type and luminosity class is briefly summarized.

Kondo, Y.↗
NASA NTRS1977

High resolution stellar spectroscopy in the balloon ultraviolet

The JSC/SRL Balloon-borne Ultraviolet Stellar Spectrometer (BUSS) comprises a 40 cm telescope, an echelle spectrograph and a SEC Vidicon detector. Operating at an altitude of 40 km this instrument provides spectra of stars with 0.1 A resolution in the 2000-3400 A region. Observations made on 19 May 1976, are discussed.

De Jager, C.↗
NASA NTRS1976

Absolute flux calibration for the Mg II observations near 2800 angstroms

Observations of the Mg II features near 2800 A, obtained with a balloon-borne ultraviolet stellar spectrometer for five stars, have been calibrated against the absolute flux measures from OAO-2 spectrometer results. Equivalent widths of the Mg II resonance doublet and their respective subordinate lines, as well as the emission intensities, were evaluated where applicable.

Kondo, Y.↗
NASA NTRS1976

The behavior of the Mg II doublet features near 2800 A observed in F, A, and B supergiants

The Mg II doublet features near 2800 A were recently observed in F-, A-, and B-type supergiants with a balloon-borne ultraviolet stellar spectrometer. The stars observed are Alpha UMi (F8 Ib), Alpha Per (F5 Ib), Eta Leo (A0 Ib), and Rho Leo (B1 Ib). The Mg II doublet features in Alpha UMi and Alpha Per show emission superposed on photospheric absorption. In the spectrum of Eta Leo, the Mg II lines are in absorption and show shortward-shifted components attributable to mass loss. In the spectrum of Rho Leo, the Mg II lines are primarily a composite of the photospheric and interstellar absorption features. The general behavior of the Mg II lines for supergiants of spectral types M through B are also discussed.

Kondo, Y.↗
NASA NTRS1976

Mass flow in the O7f binary UW Canis Majoris. II

The far-ultraviolet spectrum of UW CMa was obtained from the telescope spectrometer on the Copernicus satellite at about phase 0.25 in order to supplement earlier observations of the same kind made near phase 0.75. Analysis of the data shows that the high-temperature gas giving rise to the P Cygni features in the far-ultraviolet spectrum is located primarily around the entire binary system and does not share in the motion of either component. The effects of radiation pressure on the Roche (Jacobian) equipotential surfaces and in generating a stellar wind are discussed.

Mccluskey, G. E., Jr.↗
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

Possible Mg II emission in B stars observed from Copernicus

Four B stars, Alpha Vir, Beta Cen, Alpha Gru, and Beta Lib, were observed with the Copernicus spectrometer at a resolution of 0.1 A in order to investigate the presence of chromospheric emission. Emission was observed in Beta Cen and Alpha Gru, while the results for Alpha Vir and Beta Lib were inconclusive.

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

Skylab ultraviolet stellar spectra - Cool stars with hot secondaries

A hot companion to the G5 III star HR 3080, a single-line spectroscopic binary, has been discovered from spectra in the vacuum-ultraviolet. The companion must be a subdwarf or pre-white dwarf. A list of previously known systems of the zeta Aur and VV Cep type observed with the ultraviolet spectrograph on Skylab is also given.

Parsons, S. B.↗
NASA NTRS1976

Effects of radiation pressure on the equipotential surfaces in X-ray binaries

Equipotential surfaces incorporating the effect of radiation pressure were computed for the X-ray binaries Cen X-3, Cyg X-1 = HDE 226868, Vela XR-1 = 3U 0900-40 = HD 77581, and 3U 1700-37 = HD 153919. The topology of the equipotential surfaces is significantly affected by radiation pressure. In particular, the so-called critical Roche (Jacobian) lobes, the traditional figure 8's, do not exist. The effects of these results on modeling X-ray binaries are discussed.

Kondo, Y.↗
NASA NTRS1976

The Skylab S019 ultraviolet spectra of HD 153919 (=3U 1700-37) and HDE 226868 (=Cyg X-1)

Ultraviolet spectra of HD153919 (=3U1700-37) and HDE226868 (=Cyg X-1) were obtained with the ultraviolet objective-prism spectrograph of Skylab Experiment S019. The data consist of unwidened spectra which extend to 1,600A for HD153919 and to 2,400A for HDE226868. The wavelength resolution is about 2A to 1,400A and 12A at 2,000A. For HD153919, an unwidened spectrum of fair quality and extending to a wavelength of 1,600A was obtained at 22 sup h 08 sup m on 1 September 1973. The energy distribution in this spectrum generally resembles that of other reddened O stars. A break in continuum intensity seems to occur at a wavelength of about 1,720A. There is a suggestion of an emission line on the longward edge of the break but this could be either a chance clumping of grains or else a photographic edge-effect caused by the break.

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 NTRS1975

Ultraviolet stellar astronomy

The author has identified the following significant results. During all three Skylab missions, prism-on observations were obtained in 188 starfields and prism-off observations in 31 starfields. In general, the fields are concentrated in the Milky Way where the frequency of hot stars is highest. These fields cover an area approximately 3660 degrees and include roughly 24 percent of a band 30 deg wide centered on the plane of the Milky Way. A census of stars in the prism-on fields shows that nearly 6,000 stars have measurable flux data at a wavelength of 2600A, that 1,600 have measurable data at 2000A, and that 400 show useful data at 1500A. Obvious absorption or emission features shortward of 2000A are visible in approximately 120 stars. This represents a bonanza of data useful for statistical studies of stellar classification and of interstellar reddening as well as for studies of various types of peculiar stars.

Henize, K. G.↗
NASA NTRS1975

High temperature plasma in beta Lyrae, observed from Copernicus

High-resolution UV spectrophotometry of the complex close binary system beta Lyrae was performed with a telescope spectrometer on board Copernicus. Observations were made at phases 0.0, 0.25, 0.5, and 0.75 with resolutions of 0.2 A (far-UV) and 0.4 A (mid-UV). The far-UV spectrum is completely dominated by emission lines indicating the existence of a high-temperature plasma in this binary. The spectrum of this object is unlike that of any other object observed from Copernicus. It is believed that this high-temperature plasma results from dynamic mass transfer taking place in the binary. The current results are compared with OAO-2 observations and other observational results. The possibility that the secondary component is a collapsed object is also discussed; the Copernicus observations are consistent with the hypothesis that the spectroscopically invisible secondary component is a black hole.

Kondo, Y.↗