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The Infrared Emission Bands. III. Southern IRAS Sources
Tielens, A. G. G. M.; Allamandola, L. J.; Cohen, Martin +5 more
Airborne 5-8-micron spectra of southern IRAS sources are presented which display the strong PAH emission features. The sources studied include those in a previous paper (Cohen et al, 1986) and NGC 6302, HR 4049, and CPD -56 deg 8032. A good correlation is found between the intensity ratio of the 7.7-micron feature relative to the FIR dust continuu…
The winds of O-stars. I. an analysis of the UV line profiles with theSEI method.
Lamers, H. J. G. L. M.; Groenewegen, M. A. T.
The theoretical UV P Cygni profiles of the UV resonance lines for C IV, N V, Si IV, C III, and N IV of 26 O-type stars and one B star were calculated using the SEI method described by Lamers et al. (1987), taking into account the effects of turbulence in the wind, limb darkening, photospheric lines, and interstellar Ly alpha. The results were comp…
The Transient 42 Second X-Ray Pulsar EXO 2030+375. I. The Discovery and the Luminosity Dependence of the Pulse Period Variations
Stella, L.; Parmar, A. N.; White, N. E. +2 more
The discovery of a new transient X-ray pulsar, EXO 2030+375, that is associated with a Be star companion, is reported. The results of a series of EXOSAT observations, where the evolution of the pulsar's properties over two orders of magnitude in luminosity was monitored. The dependence of the change in pulsar period on luminosity is measured and c…
The winds of O-stars. II. The terminal velocities of stellar winds ofO-type stars.
Pauldrach, A. W. A.; Lamers, H. J. G. L. M.; Groenewegen, M. A. T.
The SEI method (Lamers et al., 1987) is used to obtain P Cygni profiles of the UV resonance lines of C IV, N V, and S IV and of the subordinate UV lines of N IV and C III observed in the spectra of 27 O-type stars. Theoretical profiles which include the turbulence effects agree well with the observations, and they can account for the deep absorpti…
The photodissociation of water in cometary atmospheres
Crovisier, J.
It is now known from laboratory and theoretical works that following water photodissociation, the OH radical is created in excited states of rotation or vibration. This fact was neglected in previous models of water photodissociation in cometary atmospheres. The goal of the present paper is to update these models. The water life time is not change…
The Transient 42 Second X-Ray Pulsar EXO 2030+375. II. The Luminosity Dependence of the Pulse Profile
Stella, L.; Parmar, A. N.; White, N. E.
During an outburst from the transient, 42 s, X-ray pulsar EXO 2030+375, marked luminosity-dependent changes in pulsar profile were observed. At high luminosities the pulse profile consisted of a smooth asymmetric main pulse separated by about 180 deg in phase from a small interpulse. As the luminosity decreased by a factor of about 100, the relati…
Velocity space diffusion of pickup ions from the water group at Comet Halley
Coates, A. J.; Glassmeier, K. -H.; Wilken, B. +2 more
We have studied the diffusion in velocity space of cometary ions using the distributions of ions measured by the implanted ion spectrometer on Giotto during the inbound pass. The measurements were transformed into a frame comoving with the solar wind and oriented with the magnetic field. The observations show the evolution of the pitch angle distr…
Pre--Main-Sequence Disk Accretion in Z Canis Majoris
Kenyon, S. J.; Stauffer, J. R.; Edwards, S. +4 more
It is suggested that the pre-main-sequence object Z CMa is a luminous accretion disk, similar in many respects to the FU Orionis variables. Z CMa shows the broad, doubled optical absorption lines expected from a rapidly rotating accretion disk. The first overtone CO absorption detected in Z CMa is blue-shifted, suggesting line formation in a disk …
Spectral classification of low-mass X-ray binary (LMXB) energy spectra with color-color diagrams.
Hasinger, G.; Truemper, J.; Schulz, N. S.
In this article we describe spectral variations of a large sample of low-mass X-ray binaries (LMXBs). The observations are done with the European X-ray Observatory EXOSAT. We decomposed the measured X-ray spectrum into three energy bands and plotted them into color-color and hardness-intensity diagrams. Correlations are compared with a few templat…
The X-ray flare and the quiescent emission from Algol as detected by EXOSAT.
Mewe, R.; van den Oord, G. H. J.
The Algol system was observed on August 18/19,1983 with different combinations of three instruments aboard EXOSAT: the low-energy channel multiplier array, the medium-energy proportional counters, and the transmission grating spectrometer. The X-ray flare observed on August 19 was analyzed and the decay phase was studied. It is shown that during t…