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IUE UV spectra of the clumpy irregular galaxy MKN297
Casini, C.; Benvenuti, P.; Heidmann, J.
Clumpy irregular galaxies are made up of 5-10 bright clumps loosely scattered in a common envelope, have excess near-UV radiation and are giant compared with classic irregular galaxies1,2. Clumps are apparently ~100 times more massive than giant H II regions such as 30 Doradus or NGC604 (ref. 3). To get an insight into their properties …
Ultraviolet and X-ray observations of the BL Lac object MK 501.
Boksenberg, A.; Penston, M. V.; Snijders, M. A. J. +3 more
We present ultraviolet and X-ray satellite observations of Mk 501. The ultraviolet data after dereddening assuming E(B-V) = 0.11 show a power-law spectrum with α = 0.51+0.10-0.15. The visible and infrared fluxes are in good agreement with this power-law if the underlying elliptical galaxy has a luminosity MV = -22.…
Far ultraviolet line profiles in the Seyfert galaxy NGC 4151.
Boksenberg, A.; Penston, M. V.; Snijders, M. A. J. +2 more
Two high-resolution far-UV spectra (1150-2000 A) of the Seyfert 1 galaxy NGC 4151 are presented which were obtained from the IUE satellite with a resolution of about 10,000. It is found that the Ly-alpha line in NGC 4151 is asymmetric and rather narrow, that the Ly-alpha/H-beta ratio varies across the line, and that there are two absorption system…
On the energy distribution in Sirius B.
Boehm-Vitense, E.; Dettmann, T.; Kapranidis, S.
A spectrum of Sirius B in the wavelength region 1100-1900 A taken with the IUE satellite shows an absolute flux and spectral energy distribution in the continuum in agreement with theoretical white-dwarf models with T(eff) of 26,000 K plus or minus 1000 K for log g equals 8.65 and R equals 5.08 x 10 to the 8th cm. The Lyman-alpha profile is also i…
Ultraviolet spectroscopy of the extreme B supergiants P Cygni and zeta 1 Scorpii.
Hutchings, J. B.
High-dispersion IUE spectra of P Cyg and Zeta-1 Sco are presented. Both show extreme line blanketing by Fe III and similar ions, formed in a low-velocity stellar wind. P Cygni also shows the same phenomenon in Fe II, at somewhat higher velocity, and appears to be cooler and less reddened then its visible spectrum suggests. Both stars show weak evi…
The UV resonance lines of zeta 1 Sco.
Wolf, B.; Appenzeller, I.
The IUE satellite has been used to obtain high-resolution UV spectrograms of the extreme B1 supergiant Zeta-1 Sco. The observed line spectrum was found to be dominated by conspicuous P Cygni profiles or strongly blueshifted circumstellar absorption lines of the resonance transitions of Al II, Mg II, Si II, C II, Al III, Si IV, C IV, and N V, and o…
HD 149499B : the hottest white dwarf ?
Wray, J. D.; Parsons, S. B.; Henize, K. G.
IUE spectra of the white dwarf component of HD 149499, discovered from the Skylab experiments S-019 UV survey, show prominent lines of He II. The star appears to be helium-rich with He/H not less than 1. The ultraviolet fluxes show the temperature to be within the range 70,000-100,000 K, with the most probable value near 85,000 K.
On the ultraviolet spectrum of Nova Cygni 1978.
Clavel, J.; Macchetto, F.; Cassatella, A. +4 more
Ultraviolet high- and low-resolution spectra of Nova Cygni 1978 have been obtained with IUE at three dates during the first month after its outburst (Sept. 13). The high-resolution spectrum of Sept. 28 is dominated, in the range 2300-2800 A, by broad undisplaced emission lines of singly ionized metals like Fe II, Cr II, and Mn II. The widths of th…
IUE observations of the extreme B1 supergiant zeta 1 Sco.
Wolf, B.; Appenzeller, I.
High-resolution (delta lambda approximately 0.2 A) and low-resolution (delta lambda approximately 6 A) spectrograms in the wavelength range from about 1200 to 3200 A have been obtained using the IUE satellite. The high-dispersion spectrograms have been used to compile lists of the stellar and interstellar absorption lines and to derive accurate wa…
Gas, dust, high energy particles and star formation in the Galactic Center
Puget, J. -L.; Lequeux, J.; Audouze, J. +1 more
The amount of gas and dust in the Galactic Center is evaluated. The COS-B and SAS-2 gamma-ray observations of the Galactic Center are discussed and limits for the flux of high-energy cosmic rays are derived from them. Consideration is given to low-energy cosmic rays which are indirectly responsible via their interaction of the interstellar matter,…