Search Publications
Heavy elements in the 2000-3000 A range of four AP stars.
Faraggiana, R.
The long wavelength range of IUE has been examined in a search for heavy elements in four chemically peculiar stars of CP2 subgroup. Pb II 2203.53 appears to be present and a lead abundance higher than the solar one is derived for HD 188041 and HD 201601. No firm indication of the presence of Th II and U II can be established in the four program s…
The region of formation of the ultraviolet high temperature resonancelines in the eclipsing binary beta Persei (Algol).
Sahade, J.; Kondo, Y.; Brandi, E. +1 more
A new series of IUE observations of Beta Persei has shown that the high temperature resonance lines of Si IV and C IV arise in a region that surrounds the brighter, early-type component of the system. The continuum spectrum corresponds to that of a B8V object, and the value of E(B-V) that yielded the best match between the two IUE regions was 0.06…
The presence of carbon in DZ star atmospheres.
Koester, D.; Weidemann, V.
A recently obtained SWP spectrum of the DZ star L 119-34 is presented. The spectrum clearly shows the presence of C I lines. This result suggests that carbon is always present in cool helium-rich white dwarf atmospheres, independent of optically based spectral classification.
A comparative study of the discrete and cross correlation techniques : an application to the NGC 5548 IUE light-curve.
Clavel, J.; Rodriguez-Pascual, P. M.; Santos-Lleo, M.
Over the past few years, cross-correlation techniques have become of increasing importance in the context of active galactic nuclei (AGN) variability studies. Inference of time delays in the response of the emission line intensities with changes in the ionizing continuum flux have the potential to yield the length scale of the broad line emitting …
Activity in late-type stars. IV. The 1980 August 20 flare on proxima Centauri revisited.
Byrne, P. B.; McKay, D.
This paper presents a reanalysis of simultaneous ultraviolet and soft X-ray observations of a flare on the dMe star, Proxima Centauri. Using an emission measure analysis, as well as density sensitive line ratios, the electron density and the total emitting volume of the flare plasma which is at midtransition region temperatures are derived. These,…
The EXOSAT view of the north and east Cygnus loop.
Ballet, J.; Rothenflug, R.
EXOSAT images of the northeast third of the Cygnus Loop are presented. The brightest parts are analyzed and the different filters on the CMA are used to put constraints on the temperature. This is especially valuable for the warm gas, for which temperatures as low as 1.4 x 10 to the 6th K in the east are estimated. The spectra obtained with EXOSAT…
X-ray and optical observations of LDS 587.
Schmitt, J. H. M. M.; Pasquini, L.; Harnden, F. R., Jr. +2 more
During an Exosat observation of the RS CVn star HD 155555 (LDS 587 A) a serendipitous X-ray source (EXO 171224-6653.9) was discovered. This paper presents an analysis of the Exosat and Einstein Observatory (HEAO 2) X-ray observations as well as optical spectra of the serendipitous X-ray source; the X-ray properties of HD 155555 are also discussed.…
Rotational modulation of hydrogen Lyman alpha flux from 44i Bootis.
Vilhu, O.; Neff, J. E.; Rahunen, T.
Observations with IUE that cover the entire 6.4 hr orbital cycle of the late-type contact binary 44i Bootis are presented. Intrinsic stellar hydrogen Lyman alpha emission flux was determined from low-resolution IUE spectra, compensating for geocoronal emission and for interstellar absorption. The variation of the stellar Lyman alpha emission flux …
The ultra-violet spectrum of the peculiar early-type supergiant, HD 157038.
Dufton, P. L.; Lennon, D. J.
Ultra-violet spectra of the nitrogen rich supergiant, HD 157038, are presented and compared with those of the normal supergiant, HD 148379. The P-Cygni profiles of the Si IV and C IV resonance lines are very similar, implying that the stars have similar masses; this is evidence against HD 157038 being in a post red supergiant evolutionary stage an…
Detection of Lyman alpha in the spectrum of a white dwarf with heliumatmosphere.
Koester, D.; Weidemann, V.
The detection of Ly-alpha absorption in a low dispersion IUE spectrum of the DBA white dwarf G200-39 is reported. The geocoronal emission was reduced by using a small aperture. For effective temperatures between 12,000 and 16,000, and log n(H)/n(He) values of -5, -4.5, -4, and -3.5, calculations giving colors and line strengths for He I 4472 A, H-…