Search Publications
The Stellar Initial Mass Function in the Giant HII Region NGC 595
Parker, Joel Wm.; Malumuth, Eliot M.; Waller, William H.
As part of a larger effort to study the resolved and composite properties of the giant H II regions in Messier 33, we have analyzed multiband HST/WFPC-2 images of NGC 595 in terms of the ionizing cluster's resolved stellar population. Photometric reductions of the PC images yield 100 stars on the UV image, 272 stars on the U image, 345 stars on th…
Superhumps and ultraviolet superdips: HST observations of OY Car.
Marsh, T. R.; Horne, K.; Cheng, F. H. +5 more
HST observations of the cataclysmic variable OY Car in superoutburst show dips in its ultraviolet light curve coincident with the optical superhump. By analogy with the light curves of X-ray dippers, the authors believe this to be due to obscuration of the hottest regions of the disc by the vertical structure flaring up at the edge of the disc. Th…
Extragalactic symbiotic systems. III. The stellar components of the systems in the Magellanic Clouds.
Vogel, M.; Schild, H.; Muerset, U.
We present multifrequency data, ranging from ultraviolet and optical spectroscopy to infrared photometry, of the confirmed symbiotic systems in both Magellanic Clouds (SMC1, SMC2, SMC3, N60, Ln358, N73, S154, S147, LMC1, N67, and S63), as well as of Sanduleak's star, whose nature remains unclear. Because of the known distance, the Magellanic symbi…
Bimodal dust emission in three classical Seyfert galaxies: NGC 3227, NGC 4051 and NGC 4151.
Meisenheimer, K.; Lemke, D.; Rodriguez Espinosa, J. M. +1 more
Far Infrared observations of the Seyfert galaxies NGC 3227, NGC 4051 and NGC 4151 are presented. These are the first data from a complete sample of Seyfert galaxies that is being observed by ISO as part of the ISOPHOT guaranteed time. The new ISO data, in combination with the IRAS data, show that the mid to far IR emission in all three objects can…
The Gaseous Extent of Galaxies and the Origin of LY alpha Systems. II. Identification of a Group or Cluster of LY alpha Absorbing Galaxies at Z approximately equal to 0.26
Lanzetta, Kenneth M.; Webb, John K.; Barcons, Xavier
We report the identification of a group or cluster of galaxies at redshift z ~ 0.26 toward the quasi-stellar object (QSO) 1545+2101 that produces a complex of corresponding Ly alpha absorption systems. This observation demonstrates that at least some groups or clusters of galaxies produce Ly alpha absorption systems and that at least some Ly alpha…
Multifrequency observations of the eclipsing symbiotic triple system CH Cyg during the 1992-94 active phase.
Ivison, R. J.; Davis, R. J.; Chochol, D. +14 more
The authors present UBV photoelectric photometry, plus optical and ultraviolet low- and high-resolution spectroscopy and MERLIN, VLA and JCMT radio/mm-wave observations of the symbiotic star CH Cyg during the period 1989.7-1995.5 which covers the 1992 outburst. On 1990 July 22 the spectrum displayed only absorption features characterized by broad …
Candidate primeval galaxies in the Hubble Deep Field.
Clements, D. L.; Couch, W. J.
The authors present the results of colour selection of candidate high-redshift (2.6 < z < 3.9) galaxies within the Hubble Deep Field based on the Lyman break at 912 Å. The authors find eight such objects in the region, giving a comoving number density comparable to that of nearby bright galaxies (for a flat q0 = 0.5, H0…
Angular sizes and luminosity evolution of faint galaxies
Im, M.; Griffiths, R. E.; Roche, N. +2 more
We investigate the number counts and the V-I colour, angular size and axis ratio distributions of 5384 faint galaxies detected with the refurbished Hubble Space Telescope (HST) Wide Field Planetary Camera, to limits of I~=25 on a 27-field strip and I~=26 on a single deeper field. These results are compared with non-evolving and pure luminosity evo…
Ultraviolet spectroscopy of the hotspot in the classical T Tauri star DI Cep: observational indications of magnetically channelled accretion.
Fernández, M.; Gómez de Castro, A. I.
T Tauri stars (TTS) are low-mass pre-main-sequence stars that are accreting mass from the surrounding disc. The hotspots detected in some of them are probably heated by the release of gravitational energy in the accretion of the disc material on to the star. In this work we study the UV spectrum of the hotspot detected in DI Cep to constrain the p…
The Wind Outflow of zeta Aurigae: A Model Revision Using Hubble Space Telescope Spectra
Harper, Graham M.; Bennett, Philip D.; Brown, Alexander +4 more
Using high-resolution spectra taken with the Goddard High-Resolution Spectrograph (GHRS) aboard the Hubble Space Telescope (HST) and with the International Ultraviolet Explorer (lUE) satellite, we reconsider the wind model of ζ Aurigae (K4 Ib + B5 V). The high quality of the HST data permits a critical test of the simplifying assumptions previousl…