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The ionization structure of planetary nebulae. V. NGC 3242.
Barker, T.
Spectrophotometric observations of emission line intensities over the spectral range 1400 A to 9600 A were made in five positions in the planetary nebula NGC 3242. In two of the positions, both the weakness of the 1548 A, 1550 A C IV resonance lines and the steepness of the Balmer decrement suggest the possibility of internal dust in the nebula. T…
COS-B gamma-ray sources and interstellar gas in the first galactic quadrant. Caravane collaboration for the COS-B satellite.
Caraveo, P. A.; Bignami, G. F.; Strong, A. W. +8 more
The consequences are considered for the high-energy gamma-ray sources of the recently established correlation between the intensity above 300 MeV, and tracers of atomic and molecular gas, in the first quadrant of the Galaxy. Using a likelihood method on the complete set of COS-B data, it is shown that there are point-like gamma-ray sources which d…
Atmospheric parameters of the variable DB white dwarf GD 358.
Koester, D.; Weidemann, V.; Vauclair, G. +3 more
This paper presents new observations of GD 358, the prototype of the class of variable white dwarfs with helium-dominated atmospheres (DB). These data, together with previous observations, are analyzed using new model atmosphere calculations. The results are Teff = 24000±1000K, log g = 8.0±0.3. This temperature is within the range predi…
Condensation of dust around the WC7 star HD 192641 (WR 137).
Telesco, C. M.; van der Hucht, K. A.; Longmore, A. J. +4 more
The WC7+ absorption class Wolf-Rayet star WR 137 (=HD 192641) is shown to have brightened significantly in the infrared since 1978, most rapidly between 1983 and mid-1984. This is ascribed to an increase in the mass loss rate and the condensation of dust grains in the stellar wind. At maximum, the dust mass was about 10-8 Msun
M 4-18 : a young cool planetary nebula.
Goodrich, R. W.; Dahari, O.
The unresolved planetary nebula M4-18 has been studied spectroscopically from the ultraviolet to the near-infrared. The nebula is found to be of very low excitation, with electron density Ne = 11,000 + or - 1,000/cu cm and electron temperature Te = 5600 + or - 1300 K, and a high O abundance. The central star is found to be among the coolest centra…
Simultaneous observations of CA II K and MG II K in T TAuri stars.
Basri, G.; Calvet, N.; Giampapa, M. S. +1 more
The first simultaneous, calibrated observations of the Ca II K and Mg II k resonance lines in T Tauri stars are presented. It is found that for T Tauri stars with mass greater than 1.5 solar mass, which have radiative cores and tend to be fast rotators, the k line seems to arise in an extended region (probably also responsible for the H-alpha emis…
The Jovian stratosphere in the ultraviolet
Encrenaz, T.; Owen, T.; Caldwell, J. +3 more
The center-of-disk reflectivity of Jupiter in the wavelength range from 1450 to 3150A˚has been computed from 30 low-dispersion IUE spectra taken during solar maximum in 1978-1980. A vertically inhomogeneous radiative transfer program is used to compute model reflectivities of various stratospheric compositions for comparison. Ammonia and acetylene…
Star formation and chemical abundances in the blue compact galaxy ESO338-IG04.
Bergvall, N.
The blue compact galaxy ESO 338 - IG04, which is undergoing a burst of star formation, is luminous for its type and has extremely blue colors. Attention is given to new broadband UBVIR photometry, spectroscopy, and both direct photographic and CCD observations of this galaxy, together with the reanalysis of a low resolution IUE spectrum. In H-alph…
An analysis of the bright white dwarf CD -38 10980.
Bruhweiler, F. C.; Wesemael, F.; Holberg, J. B. +1 more
The bright DA white dwarf CD - 38 deg 10980 is comprehensively analyzed using all available data. Detailed comparisons of the overall energy distribution and Lyman-alpha and Balmer profiles are made with theoretical predictions based on a homogeneous grid of model atmospheres. These comparisons yield a consistent, well-defined effective temperatur…
Spectrum of the high-excitation planetary nebula NGC 6741 (33-2 1).
Czyzak, S. J.; Keyes, C. D.; Aller, L. H.
Image tube observations carried out at the Lick and Mount Wilson Observatories were combined with IUE and infrared observations to study the spectra of the high-excitation planetary nebula NGC 6741. Plasma diagnostics were carried out and ion concentrations were calculated for ions from He I to Ca4(+). The ion densities and plasma diagnostics data…