Search Publications
Compact Nuclei in Moderately Redshifted Galaxies
Green, Richard F.; Griffiths, Richard E.; Ratnatunga, Kavan +1 more
The Hubble Space Telescope (HST) Wide Field Planetary Camera 2 is being used to obtain high-resolution images (<=0."15 FWHM) in the V (F606W) and I (F814W) bands for several thousand distant galaxies as part of the Medium Deep Survey (MDS). An important scientific aim of the MDS is to identify possible active galactic nucleus (AGN) candidates f…
UvbyHbeta_ photometry of main sequence A type stars.
Jordi, C.; Figueras, F.; Torra, J. +1 more
We present Stroemgren uvby and Hbeta_ photometry for a set of 575 northern main sequence A type stars, most of them belonging to the Hipparcos Input Catalogue, with V from 5mag to 10mag and with known radial velocities. These observations enlarge the catalogue we began to compile some years ago to more than 1500 stars. Our catalogue inc…
Detection of O VI lambda 1033 Emission and Far-Ultraviolet Spectral Variability in the Gravitational Lens PG 1115+080
Michalitsianos, A. G.; Nichols, J.; Oliversen, R. J.
Far-UV spectra acquired with the International Ultraviolet Explorer (IUE) of the gravitational lens PG 1115+080 and processed with the NEWSIPS software show the presence of prominent O VI λ1033 resonance line emission that is superimposed on strong far-UV continuum between 900 and 1100 A (in the z_QSO_ = 1.722 rest frame). A comparison of these sp…
Ultraviolet properties of early-type galaxies.
Alloin, D.; Pastoriza, M. G.; Bonatto, C. +1 more
We analyse the UV properties of early-type galaxies from their UV spectra in the IUE library, including both normal and active nuclei. We co-added the spectra, and hence the objects into groups of similar spectral properties in the UV, also taking into account their properties in the visible/near-infrared ranges. Although, owing to the presence of…
Performance of ion-figured silicon carbide SUMER telescope mirror in the vacuum ultraviolet
Saha, Timo T.; Leviton, Douglas B.; Glenn, Paul
Measured and theoretical encircled energy and small-angle scatter of the telescope mirror (SST) of the solar ultraviolet measurements of emitted radiation (SUMER) instrument are compared at the wavelength of 123.6 nm. Mirror performance modeling was accomplished with the Optical Surface Analysis Code software package. The modeling is based on meas…
Spectroscopic Flickering in the WC8 Nucleus of the Planetary Nebula NGC 40
Bianchi, L.; Balick, Bruce; Rodgers, B. +2 more
The flat-topped profile of the nuclear C III λ5696 Å line in the WC8 nucleus of NGC 40 shows profile shape variations on time scales of hours. Relatively narrow intensity peaks and/or valleys (i.e., "features") appear first near the center of the 1400 km s-1 wide C III line. Over the next ≈3 hr the features slide toward either the red o…
ISOCAM view of high energy sources.
Mirabel, I. F.; Boulade, O.; Claret, A. +2 more
We report the discovery of warm dust in the surroundings of the compact high energy sources SS433 and Cygnus X-1. In the jets of SS433 we have observed the infrared counterpart of the brighter X-ray knot at a distance of 50pc from the compact source. The observation reported here suggests that dust formation takes place in the ejecta, and that the…
Rotationally Resolved Spectral Studies of Pluto From 2500 to 4800 Angstroms Obtained With HST
Stern, S. Alan; Trafton, Laurence M.
Ultraviolet spectra of Pluto, excluding Charon, have been acquired at seven rotational phases by using the Faint Object Spectrograph on the Hubble Space Telescope (HST). We present the geometric albedo spectra at each rotational phase over the range 2500-4800 Å, and their average over rotational phase. We compare these results with earlier lUE spe…
Nonlinear variability of NGC 4151.
Longo, G.; Vio, R.; Rifatto, A. +2 more
We have collected all literature photometric data obtained in the B band for the Seyfert galaxy NGC4151 over the period 1910-1991, reduced them to the standard B_T_ photometric system and derived nuclear magnitudes by subtracting the light contribution from the underlying extended bulge component. The spectral analysis of the light curve shows no …
Time variable shocks in the UV: long term IUE monitoring of HH 29.
Liseau, R.; Huldtgren, M.; Fridlund, C. V. M. +1 more
We have used the IUE to the limit of its capability (~10^-15^erg/cm^2^/s/A) and present results based on long term monitoring in the UV of the Herbig-Haro object HH 29, which is dynamically coupled to the outflow activity from the deeply embedded low mass stellar object IRS5 in the L1551 dark cloud. The eight years of IUE observations confirm the …