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HST Images of the Extremely Clumpy Radio Galaxy 1138-262 at z = 2.2
Pentericci, L.; Macchetto, F.; Spinrad, H. +4 more
We present and discuss optical continuum images made with the Hubble Space Telescope of the radio galaxy 1138-262 at z = 2.2. This object possesses one of the clumpiest optical morphologies of all known high-redshift radio galaxies, consisting of a bright nucleus aligned along the radio axis and a number of smaller components distributed over a re…
Searching for Wolf-Rayet Stars in I ZW 18: the Origin of He II Emission
Schaerer, Daniel; Leitherer, Claus; de Mello, Duília F. +1 more
I Zw 18 is the most metal-poor star-forming galaxy known and is an ideal laboratory to probe stellar evolution theory at low metallicities. Using archival Hubble Space Telescope WFPC2 imaging and Faint Object Spectrograph spectroscopy, we were able to improve previous studies. We constructed a continuum-free He II λ4686 map, which was used to iden…
Spectroscopic confirmation of redshifts predicted by gravitational lensing
Ellis, Richard; Smail, Ian; Kneib, Jean-Paul +4 more
We present deep spectroscopic measurements of 18 distant field galaxies identified as gravitationally lensed arcs in a Hubble Space Telescope image of the cluster Abell2218. Redshifts of these objects were predicted by Kneib et al. using a lensing analysis constrained by the properties of two bright arcs of known redshift and other multiply imaged…
The 1996 outburst of GRO J1655-40: the challenge of interpreting the multiwavelength spectra
Horne, Keith; Shrader, C. R.; O'Brien, K. +6 more
We report on the results of a multiwavelength campaign to observe the soft X-ray transient (SXT) and superluminal jet source GRO J1655-40 in outburst using HSTRXTECGRO together with ground-based facilities. This outburst was qualitatively quite different from other SXT outbursts and from previous outbursts of this source. The onset of hard X-ray a…
ISO-SWS spectra of the C-rich AGB star R Scl and dynamical model atmospheres
Hron, J.; Kerschbaum, F.; Aringer, B. +3 more
We have monitored the spectral variations of the carbon rich AGB star R Scl in the 2-45 mu m range using the ISO-SWS instrument. We have also computed hydrostatic and hydrodynamic model atmospheres and corresponding synthetic spectra representative for two phases of R Scl. There is good qualitative agreement between observations and models in the …
The Hubble Space Telescope Key Project on the Extragalactic Distance Scale. XI. The Cepheids in NGC 4414
Kelson, Daniel D.; Illingworth, Garth D.; Huchra, John P. +21 more
We report the discovery of Cepheid variable stars in the galaxy NGC 4414, as part of the Hubble Space Telescope (HST) Key Project on the Extragalactic Distance Scale. Observations were obtained with the HST Wide-Field and Planetary Camera 2 (WFPC2) for 13 epochs at V (F555W) and 4 at I (F814W). Photometry was performed using two independent progra…
HSTUV measurements of wind structure and velocities in Local Group OB stars
Crowther, Paul A.; Prinja, Raman K.
Archival HST FOS and GHRS data sets have been used to collect ultraviolet evidence for large- and small-scale stellar wind structure in extragalactic Local Group OB stars (i.e. SMC, LMC including R136, M31, M33 and NGC 6822). By comparison with previous studies of Galactic OB stars, wind activity is principally diagnosed in individual spectrograms…
Electron temperature in the solar wind: Generic radial variation from kinetic collisionless models
Issautier, Karine; Meyer-Vernet, Nicole
We calculate analytically the radial profile of the average electron temperature in the solar wind with a kinetic collisionless model. The electron temperature profile at large distances r is the sum of a term ~r-4/3 plus a constant, with both terms of the same order of magnitude near r~1AU. This result is generic as it is weakly depend…
A New Look at Carbon Abundances in Planetary Nebulae. III. DDDM1, IC 3568, IC 4593, NGC 6210, NGC 6720, NGC 6826, and NGC 7009
Henry, R. B. C.; Kwitter, K. B.
This paper is the third in a series reporting on a study of carbon abundances in a carefully chosen sample of planetary nebulae representing a large range in progenitor mass and metallicity. We make use of the IUE Final Archive database containing consistently reduced spectra to measure line strengths of C III] λ1909 along with numerous other UV l…
Far-infrared emission of intracluster dust in the Coma galaxy cluster
Lemke, D.; Haas, M.; Mattila, K. +2 more
The ISOPHOT C200 camera aboard ISO has been used to observe the extended far infrared (FIR) emission from the Coma cluster of galaxies. Two scans with 48arcmin length across the cluster, each at 120 microns and 185 microns , were obtained at crossing position angles. The profiles of the surface brightness ratio I_120 microns / I_185 microns along …