Search Publications
Composition of comet Halley dust particles from Giotto observations
Hornung, K.; Kissel, J.; Sekanina, Z. +16 more
Mass spectra of cometary dust particles measured by the PIA dust particle analyser aboard the Giotto spacecraft show some unexpected and striking features. First, small particles below 10-14 g are much more abundant than anticipated by models. Second, most of the particles are rich in light elements such as H, C, N and O, suggesting the…
An average interstellar extinction curve for the Large Magellanic Cloud.
Fitzpatrick, Edward L.
In a recent paper (Fitzpatrick, 1985) the author examined the properties of ultraviolet interstellar extinction curves in the Large Magellanic Cloud (LMC) utilizing International Ultraviolet Explorer observations of 19 reddened O and B type LMC supergiants. The author has now obtained IUE observations of an additional eight reddened LMC OB supergi…
A Survey of Chromospherically Active Stars
Fekel, F. C.; Henry, G. W.; Moffett, T. J.
Photometric and/or spectroscopic observations have been obtained of 52 late-type stars which are suspected or known to be chromospherically active. Although not all types of observations were obtained for each star, these observations include all-sky BVRI Johnson photometry, ultraviolet spectrograms, low-dispersion blue-wavelength spectrograms, an…
Active Extragalactic Sources: Nearly Simultaneous Observations from 20 Centimeters to 1400 Angstrom
Landau, Robert; Golisch, Bill; Jones, Terry J. +15 more
IRAS, IUE, and ground-based optical, NIR, mm and submm, and radio observations obtained mainly on Apr. 9-23, 1983, are reported for 19 active extragalactic sources and eight control sources. The overall spectra of the compact active sources are shown to be well represented by continuous-curvature functions such as parabolas. The spectra are found …
The Discovery of 3.8 Hour Periodic Intensity Dips and Eclipses from the Transient Low-Mass X-Ray Binary EXO 0748-676
Parmar, A. N.; White, N. E.; Giommi, P. +1 more
Using the EXOSAT Observatory the authors have discovered a new transient X-ray burst source EXO 0748-676 that shows 8.3 minute duration X-ray eclipses that recur with a period of 3.82 hr. If the companion star is on the main sequence, the eclipse duration gives a companion mass of 0.45 M_sun; and a system inclination of 75°. Irregular intensity di…
IUE Spectra and a Resulting Model of Seyfert 2 Galaxies
Ferland, G. J.; Osterbrock, D. E.
Nearly simultaneous optical and ultraviolet observations of several Seyfert 2 galaxies are presented. A mean optical to ultraviolet emission line spectrum for Seyfert 2 galaxies is determined, and these intensities are compared with predictions of photoionization models. The UV to X-ray nonthermal continuum which ionizes this gas is examined. The …
A study of the continuum and iron K line emission from low-mass X-raybinaries.
White, N. E.; Branduardi-Raymont, G.; Hasinger, G. +4 more
It is possible to classify the spectral properties of the luminous X-ray sources which are thought to contain accreting neutron stars broadly according to whether or not the source is a coherent X-ray pulsar. In the present paper a study is reported of the spectral properties of a sample of six low-mass X-ray binaries (LMXRB). It is found that the…
X-Ray and Optical Observations of the Ultrashort Period Dwarf Nova SW Ursae Majoris: A Likely New DQ Herculis Star
Szkody, P.; Shafter, A. W.; Thorstensen, J. R.
Optical photometric and spectroscopic and X-ray observations of the dwarf nova SW UMa are presented. Moderate resolution spectroscopic data have established an orbital period of 81.8 min and have revealed that the Balmer emission lines have a multiple structure. A narrow component, similar to the s-wave component which is sometimes seen in catacly…
X-Ray Sources in Regions of Star Formation. I. The Naked T Tauri Stars
Walter, F. M.
Einstein X-ray observations of regions of active star formation in Taurus, Ophiuchus, and Corona Australis show a greatly enhanced surface density of stellar X-ray sources over that seen in other parts of the sky. Many of the X-ray sources are identified with low-mass, pre-main-sequence stars which are not classical T Tauri stars. The X-ray, photo…
Rotational modulation and flares on RS CVn and BY Dra-type stars. I. Photometry and SPOT models for BY Dra, AU Mic, AR Lac, II Peg and V711 Tau (=HR 1099).
Doyle, J. G.; Linsky, J. L.; Cellino, A. +19 more
Multicolor wide-band photometry of five active stars is presented. The observations were carried out at several places before, during and after the period of IUE observations for the purpose of determining the location, sizes, and evolution of photospheric spots at the time when chromospheric, transition region, and coronal activity data were obta…