Search Publications
New Images of the Distant, Rich Cluster CL 0939+4713 with WFPC2
Lucas, Ray A.; Sparks, William B.; Dressler, Alan +1 more
New images of the distant cluster of galaxies CL 0939+4713 at z = 0.41 have been taken with the WFPC2 on the HST. The images go deeper and show considerably more detail than the aberrated images from WFPC1. We confirm that for this cluster the Butcher-Oemler effect results from a surprisingly large population of late-type spiral and irregular gala…
HST Eclipse Mapping of Dwarf Nova OY Carinae in Quiescence: an ``Fe II Curtain'' with Mach 6 Velocity Dispersion Veils the White Dwarf
Horne, Keith; Marsh, T. R.; Hubeny, Ivan +2 more
Hubble Space Telescope (HST) observations of the eclipsing dwarf nova OY Car in its quiescent state are used to isolate the ultraviolet spectrum (1150-2500 A at 9.2 A Full Width at Half Maximum (FWHM) resolution) of the white dwarf, the accretion disk, and the bright spot. The white dwarf spectrum has a Stark-broadened photospheric L(alpha) absorp…
Charged-Particle Motion in Multidimensional Magnetic Field Turbulence
Giacalone, J.; Jokipii, J. R.
We present a new analysis of the fundamental physics of charged-particle motion in a turbulent magnetic field using a numerical simulation. The magnetic field fluctuations are taken to be static and to have a power spectrum which is Kolmogorov. The charged particles are treated as test particles. It is shown that when the field turbulence is indep…
The Cepheid Distance to NGC 5253: Calibration of M(max) for the Type I Supernovae SN 1972E and SN 1895B
Panagia, N.; Saha, A.; Labhardt, Lukas +4 more
The apparent V distance modulus of NGC 5253, parent galaxy to the Type Ia supernovae SN 1972E and SN 1895B, is (m - M)_AV_ = 28.06+/-0.06 mag (internal error) determined from 11 Cepheid variables discovered with the Hubble Space Telescope. The internal differential absorption between the Cepheids and the two SNs is taken to be zero based on four i…
Interstellar Carbon Monoxide toward zeta Ophiuchi
Gilliland, Ronald L.; Federman, S. R.; Lambert, David L. +1 more
Interstellar CO A-X bands in the spectrum of zeta Oph were recorded at high Sound-to-Noise (S/N) with grating G160M of the Goddard High Resolution Spectrograph on the Hubble Space Telescope. Isotopic fractionation of CO is severe: CO-12/CO-13 = 167, C(16)O/C(18)O approximately equal to 1550 and C(16)O/C(17)O is greater than 5900 are found where C-…
NGC 3603 and Its Wolf-Rayet Stars: Galactic Clone of R136 at the Core of 30 Doradus, but without the Massive Surrounding Cluster Halo
Drissen, Laurent; Moffat, Anthony F. J.; Shara, Michael M.
HST/PC images of the dense stellar cluster at the center of the Galaxy's most massive visible H II region, NGC 3603, reveal remarkable similarity to the dense core R136 in the Local Group's most massive Giant H II region, 30 Dor. The projected star density for stars brighter than M_V_ = -5.0 in both objects increases inwards to the last data bin i…
The Ultraviolet Pulsations of the Cataclysmic Variable AE Aquarii as Observed with the Hubble Space Telescope
Eracleous, Michael; Horne, Keith; Wood, Janet H. +3 more
We present the results of high time resolution UV spectroscopy and simultaneous high-speed UBVR photometry of AE Aqr. The UV spectra were obtained with the Faint Object Spectrograph aboard the Hubble Space Telescope (HST), and the photometry was carried out with the 82 sec telescope at McDonald Observatory. Our study focuses on the coherent 33 sce…
The Hubble Space Telescope Medium Deep Survey with the Wide Field and Planetary Camera. I. Methodology and Results on the Field near 3C 273
Im, M.; Glazebrook, K.; Illingworth, G. D. +21 more
We present results from the Medium Deep Survey (MDS), a Key Project using the Hubble Space Telescope. Wide Field Camera images of random fields have been taken in "parallel mode" with an effective resolution of 0'2 FWHM in the V(F555W) and I(F785LP) filters. The exposures presented here were targeted on a field 6' away from 3C 273, and resulted in…
An X-Ray and Optical Study of the Supernova Remnant W44
Rho, Jeonghee; Hester, J. Jeff; Schlegel, Eric M. +1 more
We report the results of a 8000 s observation of the supernova remnant W44 using the ROSAT Position Sensitive Proportional Counter (PSPC). The image shows the same centrally peaked morphology observed by the Einstein IPC and contrasts with the shell-like radio morphology. The eastern limb shows a lack of X-ray emission within the radio shell, prob…
Galaxy Pairs in Deep HST Images: Evidence for Evolution in the Galaxy Merger Rate
Keel, William C.; Windhorst, Rogier A.; Burkey, Jordan M. +1 more
We use four deep serendipitous fields observed with the HST Wide-Field Camera to constrain the rate of galaxy merging between the current epoch and z~0.7. Since most mergers occur between members of bound pairs, the merger rate is given to a good approximation by (half) the rate of disappearance of galaxies in pairs. An objective criterion for pai…