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Hubble Space Telescope Observations of Candidate Young Globular Clusters and Stellar Associations in the Recent Merger Remnant NGC 3921

Whitmore, Bradley C.; Fall, S. Michael; Miller, Bryan W. +1 more

New, high-resolution images of NGC 3921 obtained with the Wide Field and Planetary Camera 2 of the refurbished HST are presented. NGC 3921 is the remnant of two merged disk galaxies and thought to be a 0.7+/-0.3 Gyr old protoelliptical. A search for star clusters has yielded 102 candidate globular clusters (GC) and 49 separate, more extended stell…

Spectrophotometric Standards From the Far-UV to the Near-IR on the White Dwarf Flux Scale

Bohlin, Ralph C.

The second generation instruments to be installed in 1997 on the Hubble Space Telescope (HST) require spectrophotometric standard stars for flux calibrations to 1.1 µm for the imaging spectrograph (STIS) and to 2.5 µm for the infrared camera (NICMOS). Calculated model atmosphere flux distributions from 0.1 to 3 µm for four pure h…

Hubble Space Telescope Observations of the HH 47 Jet: Narrowband Images

Hartigan, Patrick; Bally, John; Schwartz, Richard D. +4 more

Cometary Knots in the Helix Nebula

O'Dell, C. R.; Handron, Kerry D.

The Cometary Knots in the Helix Nebula have shown themselves in observations with the Hubble Space Telescope's WFPC2 to be well-resolved photoionized surfaces on the central star facing sides of neutral clouds. Material streams backwards from the rims of the ionized surfaces, producing tails. The neutral cores of the Cometary Knots are seen in ext…

The Final Archive and Recalibration of the International Ultraviolet Explorer (IUE) Satellite

Nichols, Joy S.; Linsky, Jeffrey L.

Since 1978 the International Ultraviolet Explorer (lUE) satellite has been acquiring the largest collection of astronomical ultraviolet spectra that will likely be obtained in the foreseeable future. The more than 100 000 spectral images, from which low and high dispersion spectra are extracted, include a very broad range of sources from solar sys…

The Centers of Early-Type Galaxies With HST. II. Empirical Models and Structural Parameters

Faber, S. M.; Dressler, A.; Byun, Y. -I. +6 more

We present a set of structural parameters for the central parts of 57 early-type galaxies observed with the Planetary Camera of the Hubble Space Telescope. These parameters are based on a new empirical law that successfully characterizes the centers of early-type galaxies. This empirical law assumes that the surface brightness profile is a combina…

Hubble Space Telescope Ultraviolet Images of Five Circumnuclear Star-Forming Rings

Filippenko, A. V.; Macchetto, F. D.; Ho, L. C. +5 more

We present UV (~2300 A) images, obtained with the Hubble Space Telescope (HST) Faint Object Camera, of the central 20" of five galaxies containing circumnuclear star-forming rings. The five galaxies are from a well- defined sample of 103 normal, nearby galaxies we have observed with HST. At the HST resolution (0.05"), the rings break up into discr…

Hubble Space Telescope Observations of M32: The Color-Magnitude Diagram

Holtzman, J. A.; Faber, S. M.; Stetson, P. B. +9 more

We present a V-I color-magnitude diagram for a region 1' - 2' from the center of M32 based on Hubble Space Telescope WFPC2 images. The broad color-luminosity distribution of red giants shows that the stellar population comprises stars with a wide range in metallicity. This distribution cannot be explained by a spread in age. The blue side of the g…

Nuclei of Nearby Disk Galaxies.I.A Hubble Space Telescope Imaging Survey

Franx, Marijn; Illingworth, Garth D.; MacKenty, John W. +1 more

We present deconvolved images of the central regions of 20 nearby disk galaxies, obtained with the original Planetary Camera of the Hubble Space Telescope. The galaxies span a range in Hubble type from S0 to Sm. We have measured surface brightness profiles, and inverted these to estimate luminosity-density profiles. Surface brightness profiles in …

The Discovery of Young, Luminous, Compact Stellar Clusters in the Starburst Galaxy NGC 253

Watson, A. M.; Holtzman, J. A.; Stapelfeldt, K. R. +14 more

We report the discovery of four young, luminous, compact stellar clusters in the central region of the starburst spiral galaxy NGC 253. One cluster has an intrinsic M_V_ of about -15 or brighter, an inferred mass in excess of 1.5 x 10^6^ M_sun_, assuming a Salpeter IMF from 0.08 M_sun_ to 100 M_sun_, and is resolved with a half-light radius of abo…