Search Publications
Molecules in celestial objects. I - Circumstellar CO in 9 Cephei /B2Ib/
Tarafdar, S. P.; Swamy, K. S. K.; Vardya, M. S.
The column density of interstellar CO towards 9 Cep has been determined and a tentative identification of circumstellar CO around the star made. This is the first identification of a molecule around a B star. The circumstellar column density of CO and rate of mass loss have been estimated.
Ultraviolet spectroscopy of the VELA SNR.
Danziger, I. J.; Clark, D. H.; Wood, R.
A preliminary ultraviolet spectrum secured from the IUE satellite, of a bright filament in the Vela supernova remnant, displays both emission-line and continuum components. The emission-line spectrum shows the same anomalously low carbon-line strength reported previously for the Cygnus Loop. The continuum emission may be explained in terms of norm…
Does phi Herculis have a corona ?
Stickland, D. J.; Dworetsky, M. M.
High resolution IUE spectra of Phi Herculis have been searched for indicators of a chromosphere or transition region but none have been found, which could mean that the soft X-rays observed by HEAO-1 may have an alternative origin than a conventional corona in this Hg-Mn star. The possibility that white dwarfs could be responsible for the X-rays f…
Simultaneous spectroscopic (UV MG II and AL II lines) photometric variations of zet1 SCO (HD 152236).
Clavel, J.; Bianchi, L.; Cassatella, A. +2 more
Repeated IUE observations of HD152236 show variations in the line profiles of the two Mg II doublets at about 2800 A and of the Al II lambda 1670 line. A series of puffs in the expanding envelope have been identified, implying a non-stationary mass loss process. A phase of particularly discontinuous loss of matter has been correlated with a sharp …
IUE observations of N V, a diagnostic of hot interstellar gas
Smith, L. J.; Hartquist, T. W.
The paper reports IUE observations of interstellar N V toward a number of Wolf-Rayet stars and compares the derived number density with that predicted by one theory of the interstellar medium. The observed N V/O VI ratio implies that most of the hot gas in the interstellar medium is at T about 2.3 x 10 to the 5th K.
A search for absorption in the fourth positive system of CO in the spectrum of the planetary nebula IC 418.
Clavel, J.; Flower, D. R.
The continuous emission of IC 418 has been observed at high dispersion with the IUE satellite and the spectrum searched for the A1Π-&Chi1Σ+ bands of CO. It was not possible to unequivocally detect these CO bands in IC 418. However, an upper limit to the absorption by CO was determined, giving a column density w…
Extinction of NGC 7027.
Seaton, M. J.
Emission intensities of recombination lines in hydrogenic spectra are known accurately relative to intensities in the free-free radio continuum. For NGC 7027 intensities have been measured for the radio continuum and for H I and He II lines in the wavelength range from 2.17 microns to 1640 A; comparison with the calculated emission intensities giv…
Maximum-entropy image processing in gamma-ray astronomy.
Strong, A. W.; Bennett, K.; Skilling, J.
In order to make the fullest use of the information contained in data from a spark-chamber telescope, an image processing approach, is required. It is shown how the maximum-entropy reconstruction technique can be applied in a modification appropriate to a situation of low statistical weight per resolution solid angle, as usually occurs with presen…
Observations of 3C 390.3 with the International Ultraviolet Explorer.
Perryman, M. A. C.; Ferland, G. J.; Longair, M. S. +1 more
Observations of the radio galaxy 3C 390.3 made with IUE are presented; these allow separate determinations of the Lyman/Balmer ratios in both the narrow and broad emission-line regions. The broad-line L-alpha/H-alpha ratio confirms the anomalous results found previously in quasars; in this case a ratio is found about 15 times smaller than that pre…
Oxygen VI in stellar winds.
Morton, D. C.
A review of observational evidence for five-times ionized oxygen (OVI) in stars and new high-resolution spectral scans obtained with Copernicus satellite are presented to show how this phenomenon varies with spectral type. The region of the OVI resonance doublet was observed in nine stars with the Copernicus spectrometer, and P Cygni profiles or s…