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Caltech Faint Galaxy Redshift Survey. XIV. Galaxy Morphology in the Hubble Deep Field (North) and Its Flanking Fields to Z=1.2
Hogg, David W.; Cohen, Judith G.; van den Bergh, Sidney +1 more
Morphological classifications are reported for Hubble Space Telescope images of 241 galaxies in the Hubble Deep Field and its flanking fields with measured redshifts in the interval 0.25<z<1.2, drawn from a magnitude-limited redshift survey to R=24.0. The galaxies are divided into three groups with redshifts in the intervals 0.25-0.6, 0.6-0.…
Hubble Space Telescope WFPC2 Photometry of M33: Properties of the Halo Star Clusters and Surrounding Fields
Sarajedini, Ata; Schommer, Robert; Geisler, Doug +1 more
We present CCD photometry for 10 fields centered on halo star clusters in the nearby spiral galaxy M33. The data are based on Hubble Space Telescope Wide-Field Planetary Camera 2 observations in the F555W (~V) and F814W (~I) filters. The resultant color-magnitude diagrams (CMDs) extend ~1.5 mag below the horizontal branch (HB). From these diagrams…
The Dwarf Spheroidal Companions to M31: WFPC2 Observations of Andromeda II
Da Costa, G. S.; Armandroff, T. E.; Caldwell, Nelson +1 more
The Hubble Space Telescope WFPC2 camera has been used to image Andromeda II, a dwarf spheroidal (dSph) companion to M31. The resulting color-magnitude (c-m) diagrams reveal the morphology of the horizontal branch (HB) in this dwarf galaxy. We find that like Andromeda I, and like most of the Galactic dSph companions, the HB morphology of And II is …
Hubble Space Telescope Photometry of Hodge 301: An ``Old'' Star Cluster in 30 Doradus
Grebel, Eva K.; Chu, You-Hua
We present Hubble Space Telescope Planetary Camera UVI data for Hodge 301, the little-studied cluster 3' northwest of the central ionizing cluster R136 in 30 Doradus. The average reddening of Hodge 301 is found to be <EB-V>=0.28+/-0.05 mag from published infrared and ultraviolet photometry. Using two different sets of evolutionary…
Origin of Color Gradients in Elliptical Galaxies
Kobayashi, Chiaki; Kodama, Tadayuki; Tamura, Naoyuki +2 more
The origin of color gradients in elliptical galaxies is examined by comparing model gradients with those observed in the Hubble Deep Field. The models are constructed so as to reproduce color gradients in local elliptical galaxies either by a metallicity gradient or by an age gradient. By looking-back a sequence of the color gradient as a function…
HST/WFPC2 and VLT/ISAAC Observations of Proplyds in the Giant H II Region NGC 3603
Grebel, Eva K.; Brandner, Wolfgang; Chu, You-Hua +6 more
We report the discovery of three proplyd-like structures in the giant H II region NGC 3603. The emission nebulae are clearly resolved in narrowband and broadband HST/WFPC2 observations in the optical and broadband VLT/ISAAC observations in the near-infrared. All three nebulae are tadpole shaped, with the bright ionization front at the head facing …
A Redetermination of the Mass of Procyon
Brown, R. H.; Provencal, J. L.; Wu, H. +12 more
The parallax and astrometric orbit of Procyon have been redetermined from PDS measurements of over 250 photographic plates spanning 83 years, with roughly 600 exposures used in the solution. These data are combined with two modern measurements of the primary-white dwarf separation, one utilizing a ground-based coronagraph, the other, the Planetary…
Binary Star Differential Photometry Using the Adaptive Optics System at Mount Wilson Observatory
Bagnuolo, William G., Jr.; Mason, Brian D.; ten Brummelaar, Theo +4 more
We present photometric and astrometric results for 36 binary systems observed with the natural guide star adaptive optics system of the Mount Wilson Institute on the 100 inch (2.5 m) Hooker Telescope. The measurements consist of differential photometry in U, B, V, R, and I filters along with astrometry of the relative positions of system component…
The Black Hole in IC 1459 from Hubble Space Telescope Observations of the Ionized Gas Disk
van der Marel, Roeland P.; de Zeeuw, P. Tim; Carollo, C. Marcella +1 more
The peculiar elliptical galaxy IC 1459 (MV=-21.19, D=16.5 h-1 Mpc) has a fast counterrotating stellar core, stellar shells and ripples, a blue nuclear point source, and strong radio core emission. We present results of a detailed Hubble Space Telescope study of IC 1459, and in particular its central gas disk, aimed at constra…
Two Groups of Nearly Coeval Star Clusters in the Small Magellanic Cloud
Fall, S. Michael; Rich, R. Michael; Zurek, David +1 more
We report new photometry and main-sequence turnoff ages for seven populous star clusters in the SMC with MV<-6 and age greater than 1 Gyr, using the Wide Field Planetary Camera 2 on board the Hubble Space Telescope. In contrast to the accepted picture, these clusters appear to have formed in two brief intervals, the oldest 8+/-2 Gyr …