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Quantitative UV spectroscopy of early O stars in the Magellanic Clouds. The determination of the stellar metallicities
Lennon, D. J.; Pauldrach, A. W. A.; Puls, J. +4 more
UV spectra of 4 O-stars in the Magellanic Clouds obtained with the Faint Object Spectrograph of the Hubble Space Telescope are analyzed with respect to metallicity. With the stellar parameters T_eff,log g, R_{*}, and the mass loss rates dot {M} known from optical analyses, the metal abundances including iron group elements are derived in two steps…
Asymmetry and Frequencies of Low-Degree p-Modes and the Structure of the Sun's Core
Kosovichev, A. G.; Scherrer, P. H.; Appourchaux, T. +3 more
An accurate determination of the frequencies of low-degree solar p-modes is an important task of helioseismology. Using 679 days of solar oscillation data observed in Doppler velocity and continuum intensity from two Solar and Heliospheric Observatory instruments (the Michelson Doppler Imager and the SunPhotoMeter), we show that fitting the spectr…
Global model of the corona with heat and momentum addition
Wu, S. T.; Poletto, G.; Suess, S. T. +1 more
We have been developing a series of global coronal models directed at a better simulation of empirical coronal hole and streamer properties. In a previous study, a volumetric heat source was used to produce a thin current sheet above streamers and high solar wind speed in the coronal hole. This improved the preexisting coronal structure for corona…
The HR-diagram from HIPPARCOS data. Absolute magnitudes and kinematics of BP - AP stars
Luri, X.; Figueras, F.; Royer, F. +5 more
The HR-diagram of about 1000 Bp - Ap stars in the solar neighbourhood has been constructed using astrometric data from Hipparcos satellite as well as photometric and radial velocity data. The LM method \cite{luri95,luri96} allows the use of proper motion and radial velocity data in addition to the trigonometric parallaxes to obtain luminosity cali…
A Cluster of Low-Redshift LYalpha Clouds toward PKS 2155-304. I. Limits on Metals and D/H
Carilli, Chris; Shull, J. Michael; Stocke, John T. +4 more
We report observations from the Hubble Space Telescope (HST) and the VLA on the galactic environment, metallicity, and D/H in strong low-redshift Lyalpha absorption systems toward the bright BL Lac object PKS 2155-304. These studies are intended to clarify the origin and chemical evolution of gas at large distances from galaxies. With GHRS/G160M d…
A complete infrared Einstein ring in the gravitational lens system B1938+666.
Blandford, R. D.; Bremer, M. N.; Jackson, N. +7 more
We report the discovery, using NICMOS on the Hubble Space Telescope, of an arcsec-diameter Einstein ring in the gravitational lens system B1938 +666. The lensing galaxy is also detected, and is most likely an early-type galaxy. Modelling of the ring is presented and compared with the radio structure from MERLIN maps. We show that the Einstein ring…
The far infrared line spectrum of the protostar IRAS 16293-2422
Liseau, R.; White, G. J.; Ceccarelli, C. +7 more
We report mid-IR wavelength observations toward the low mass star forming region IRAS 16293-2422 between 45microns - 197microns with the Long Wavelength Spectrometer (LWS) on board ISO, and of the CI(609microns ) line observed with the JCMT. A map of the CII(157microns ) line shows that the region is relatively uncontaminated by Photo-Dissociation…
ISO observations of candidate young brown dwarfs
Torra, J.; Rieke, G. H.; Laureijs, R. J. +2 more
ISOCAM measurements or upper limits for low mass members of the rho Ophiuchi embedded cluster extend the sampling of the spectral energy distributions already obtained from the ground towards longer wavelengths, where emission by circumstellar material is significant. Good fits to the combined (ground-based + ISOCAM) photometry are obtained with t…
Globular clusters in the blue compact galaxy ESO 338-IG04 (Tololo 1924-416), as tracers of the star formation history. Results from HST/WFPC2 observations
Oestlin, Goeran; Bergvall, Nils; Roennback, Jari
Multicolour images of the starbursting metal poor blue compact galaxy ESO 338-IG04 have been obtained with the Wide Field Planetary Camera 2 on board the Hubble Space Telescope. In the images we find numerous point-like sources concentrated towards the main body of the galaxy, which we identify as globular cluster candidates. We show that these ob…
B0712+472: a new radio four-image gravitational lens
Muxlow, T. W. B.; Pearson, T. J.; Bremer, M. +14 more
A new four-image gravitational lens system, B0712+472, has been discovered during the Cosmic Lens All-Sky Survey. This system consists of four flat-spectrum radio images that are also seen on a Hubble Space Telescope (HST) image, together with the lensing galaxy. We present MERLIN, VLA and VLBA maps and WHT spectra of the system as well as the HST…