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ISO observations of Uranus: The stratospheric distribution of C_2H_2 and the eddy diffusion coefficient
Kessler, M. F.; Lellouch, E.; Feuchtgruber, H. +7 more
The infrared spectrum of Uranus has been recorded between 7 and 16.5mu m with the grating mode of the Short-Wavelength Spectrometer of ISO, with a resolving power of 1500. The 6-12mu m spectrum of Uranus has also been recorded at lower resolution (R=90) by the PHOT instrument in spectroscopic mode. The spectra show no signatures other than the C_2…
X-Rays from Superbubbles in the Large Magellanic Cloud. V. The H II Complex N11
Wakker, Bart P.; Chu, You-Hua; Smith, R. Chris +3 more
The giant H II complex N11 in the Large Magellanic Cloud contains OB associations at several different stages in their life histories. We have obtained ROSAT PSPC and HRI X-ray observations, Curtis Schmidt CCD images, echelle spectra in Hα and [N II] lines, and IUE interstellar absorption line observations of this region. The central bubble of N11…
The galactic globular cluster NGC 1851: its dynamical and evolutionary properties
Saviane, I.; Zaggia, S.; Piotto, G. +3 more
We have completely mapped the Galactic globular cluster NGC 1851 with large-field, ground-based VI CCD photometry and pre-repair HST/WFPC1 data for the central region. The photometric data set has allowed a V vs. (V-I) colour-magnitude diagram for ~ 20500 stars to be constructed. >From the apparent luminosity of the horizontal branch (HB) we de…
The Mid- and Far-Infrared Spectral Energy Distribution of Seyfert Galaxies
Rodriguez Espinosa, J. M.; Perez Garcia, A. M.; Santolaya Rey, A. E.
Multi-line analysis of the spectra of Herbig Ae/Be stars
Bouret, J. -C.; Catala, C.
We present the results of the study of four Herbig Ae/Be stars (AB Aur, BD+46(deg) 3471, HD250550, BD+61(deg) 154). For each of them, semi-empirical models of the structure of their winds have been constructed; we then calculated the Hα line, the Balmer discontinuity, as well as the C IV 1548 Angstroms and Mg II h or k resonance lines. Thanks to c…
Hubble Space Telescope Eclipse Observations of the Nova-like Cataclysmic Variable UX Ursae Majoris
Horne, Keith; Hubeny, Ivan; Long, Knox S. +4 more
We present and analyze Hubble Space Telescope observations of the eclipsing nova-like cataclysmic variable UX UMa obtained with the Faint Object Spectrograph. Two eclipses each were observed with the G160L grating (covering the ultraviolet waveband) in 1994 August and with the PRISM (covering the near-ultraviolet to near-infrared) in November of t…
HIPPARCOS parallaxes and period-luminosity relations of high-amplitude delta Scuti stars
Hog, E.; Petersen, J. O.
Hipparcos parallaxes of high-amplitude delta Scuti stars are used to derive a period-luminosity relation with a scatter of about +/-0.1 mag, which is independent from photometric calibrations to absolute luminosities. Comparisons with several P-L relations from the literature show satisfactory agreement, and all deviations from the Hipparcos mean …
Saturn's hydrogen aurora: Wide field and planetary camera 2 imaging from the Hubble Space Telescope
Krist, John E.; Holtzman, Jon A.; Trauger, John T. +8 more
Wide field and planetary camera 2/Hubble Space Telescope (WFPC2/HST) images of Saturn's far ultraviolet aurora reveal emissions confined to a narrow band of latitudes near Saturn's north and south poles. The aurorae are most prominent in the morning sector with patterns that appear fixed in local time. The geographic distribution and vertical exte…
Evidence in Support of the ``Nanoflare'' Picture of Coronal Heating from SUMER Data
Judge, P. G.; Wilhelm, K.; Schühle, U. +3 more
We study high signal-to-noise profiles of O IV emission lines obtained using the SUMER instrument on SOHO. Data for the quiet Sun obtained close to the disk center and at the solar limb were acquired. After careful data processing in which disk data were analyzed differentially against limb data, we find a systematic correlation between a density-…
Inclined Gas Disks in the Lenticular Seyfert Galaxy NGC 5252
Wilson, Andrew S.; Morse, Jon A.; Tsvetanov, Zlatan I. +1 more
We discuss the morphology and kinematics of the extended gas in the type 2 Seyfert galaxy NGC 5252 based on Hubble Space Telescope (HST) WFPC2 continuum and emission-line images (including a new [O III] λ5007 image) and a ground-based Fabry-Perot (F-P) velocity map of the ionized gas. The fine-scale morphology of the ionized gas in this galaxy's v…