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The iron abundance in helium star HD 144941.
Jeffery, C. S.; Harrison, P. M.
The iron abundance in the helium star HD 144941 has been measured from ultraviolet #1iii lines. It is 1.9+/-0.2dex below solar and confirms the low metallicity (Z=0.0003) previously determined from measurements of CNO and other light elements. The result is important because the low CNO metallicity must be reflected in the iron-group elements in o…
Atomic Physics with the Goddard High Resolution Spectrograph on the Hubble Space Telescope. III. Oscillator Strengths for Neutral Carbon
Federman, S. R.; Cardelli, Jason A.; Zsargo, J.
High quality spectra of interstellar absorption from C I toward β1 Sco, ρ Oph A, and χ Oph were obtained with the Goddard High Resolution Spectrograph on HST. Many weak lines were detected within the observed wavelength intervals: 1150-1200 Å for β1 Sco and 1250-1290 Å for ρ Oph A and χ Oph. Curve-of-growth analyses were perf…
Lyα Absorption-Line Systems in the Gravitational Lens Q0957+5611
Bruhweiler, F. C.; Michalitsianos, A. G.; Kazanas, D. +6 more
Far-ultraviolet spectra of the gravitational lens components Q0957+561A and B were obtained with the Hubble Space Telescope Faint Object Spectrograph (HST FOS). Two previously known absorption-line systems were detected at redshifts zdamped = 1.3911 and zLyα = 1.1249. Their prominent absorption features are superposed on inte…
Measurement of the ^12C/^13C ratio in planetary nebulae
Walsh, J. R.; Clegg, R. E. S.; Storey, P. J. +1 more
The ^12C/^13C isotopic ratio in the ionized gas in three planetary nebulae has been measured using a new method based on transitions caused by hyperfine effects. The C III] multiplet near 1908A has an F=1/2-1/2 transition at 1909.6A that is completely forbidden in ^12C, but allowed as a result of the non-zero nuclear spin of ^13C. The transition p…
The Cluster Mission: ESA`S Spacefleet to the Magnetosphere
Credland, J.; Mecke, G.; Ellwood, J.
The Nature of the Far-Infrared Emission from Seyfert Galaxies
Pérez García, A. M.; Rodríguez Espinosa, J. M.
Optical R-band imaging data and far-infrared (FIR) Infrared Space Observatory data from Seyfert galaxies are combined to show that the compact optical emission from the nuclear and circumnuclear region correlates reasonably well with the warm FIR emission that is observed in these objects, while the extended optical emission, which essentially ori…
A photometric and spectroscopic study of the association LH47 in the superbubble N44 in the LMC
Bomans, D. J.; Dieball, A.; Will, J. -M.
The OB association LH47 inside the superbubble N44 in the Large Magellanic Cloud (LMC) is analyzed with CCD photometry. For the bright blue stars spectra in the optical and UV have been taken. The observed U, B, and V magnitudes and colours are converted to Teff and L. From isochrone fits to the colour magnitude diagram (CMD), we find a…
The dust sensor for CASSINI
Grün, Eberhard; Srama, Ralf
In October 1997 a unique mission to the Saturnian system will be launched by NASA, the CASSINI mission. One goal of this mission is to study the Saturnian dust environment, and for this task, the COSMIC DUST ANALYZER (CDA) has been developed and is currently under test. Impact ionization is used to determine the speed (1 - 100 km/s) and the mass (…
The Hardness-Intensity Correlation in Bright Gamma-Ray Bursts
Hurley, K.; Sunyaev, R.; Boer, M. +10 more
The presence of a hardness-intensity correlation (HIC) is demonstrated in a sample of 77 bright bursts observed by the Phebus and Ulysses gamma-ray burst (GRB) experiments. Using simulations, we find a significant correlation (5 σ) between the peak spectral hardness and the peak intensity in Phebus. Moreover, the HIC is compatible with a single re…
Mid-infrared spectroscopy of the hyperluminous infrared galaxy IRAS P09104+4109.
Kawara, K.; Murayama, T.; Taniguchi, Y. +2 more
We present mid-infrared spectroscopy of the hyperluminous infrared galaxy IRAS 09104+4109 based on observations with ISOCAM CVF. We have detected the emission peak around 8µm as well as the absorption feature around 10µm possibly due to silicate, providing evidence for a dusty torus around the central engine. Comparing the observationa…