Search Publications
The Metallicity Dependence of the Stellar Luminosity and Initial Mass Function: HST Observations of Open and Globular Clusters
Tanvir, Nial; Gilmore, Gerard; von Hippel, Ted +2 more
Using HST and the WFPC2 we have acquired very deep V- and I-band photometry of stars in NGC 2420 and NGC 2477 to study cluster luminosity functions at approximately solar metallicity. We have determined these cluster luminosity functions down to M1=10.5(0.2 Msun) and find that the luminosity function of NGC 2420 turns over at…
AO 0235 + 164 and Surrounding Field: Surprising HST Results
Cohen, Ross D.; Burbidge, E. M.; Lyons, R. W. +2 more
Results obtained with the Hubble Space Telescope on the highly variable radio, x-ray, and γ-ray emitting QSO (or BL Lac object) AO 0235+164 are presented and analyzed. WFPC2 images were obtained in 1994 June, when AO 0235+164 was bright (m ~ 17), and the results are described in Sec. 3. After subtraction of the PSF of the QSO, hereafter called AO …
Hubble Space Telescope Imaging of Dust Lanes and Cometary Structures in the Inner Disk of the Cartwheel Ring Galaxy
Lucas, Ray A.; Struck, Curtis; Appleton, Philip N. +1 more
We have obtained high-resolution B and I-band Hubble Space Telescope (HST) images of the Cartwheel ring galaxy which provide unprecedented views of the structure and color of the two rings and spokes. Here, we focus on the imaging results for the central regions of the Cartwheel, its inner ring and spokes. Prior to these observations there was sur…
An HST Study of OB Associations and Star Clusters in M101
Stetson, Peter B.; Bresolin, Fabio; Kennicutt, Robert C., Jr.
The massive stellar content, the OB associations and the star clusters in an HST field in M101 = NGC 5457 are investigated. A clustering algorithm yields 79 putative associations. Their size distribution is similar to that found in the Magellanic Clouds, M31, and M33, with an average size around 90 pc. The V luminosity function for the stars conta…
The Hot Component of RS Ophiuchi
Mikolajewska, Joanna; Kenyon, Scott J.; Wade, Richard A. +2 more
We analyze optical and ultraviolet spectrophotometry of the quiescent recurrent nova RS Ophiuchi. Our preferred model for this binary consists of an M-type giant and a B-type shell star with a luminosity of Lh∼100-600 Lsun. The ejecta from the recent outburst are slightly enhanced in helium relative to the solar abundance, wh…
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…
The Environments of Supernovae in Archival Hubble Space Telescope Images
Filippenko, Alexei V.; Leibundgut, Bruno; Barth, Aaron J. +2 more
We have examined the immediate environments of several supernovae using archival prerefurbishment Hubble Space Telescope images to search for clues to the nature of the progenitor stars. For the Type II supernova 1968L in M83 the colors of nearby star clusters indicate ages of <~ 6-7 x 10^6^ yr, implying an initial mass of ~> 25-30 M_sun_ fo…
Study of Time Varitions of UV Continuum and Emission Lines in 3C 390.3
Zheng, Wei
Based on the IUE SWP spectra obtained between 1978 and 1994, the variations of the UV continuum and the Lyα and C IV emission lines of the broad-line radio galaxy 3C 390.3 are studied. The UV continuum between 1220 and 1990 A has varied considerably. In 1991 August, the flux at 1360 A reached a maximum level of 1.3 x 10^14^ erg cm^-2^ s^-1^ A^-1^,…
WFPC2 Imaging of the Starburst Galaxy NGC 5253
Gorjian, Varoujan
A high-resolution F606W band image has been obtained with the WFPC2 instrument on the Hubble Space Telescope of the unusual starburst galaxy NGC 5253. This is a dwarf elliptical galaxy with a very young starburst in progress. The HST image is compared to ground-based data in the Hα and 2 cm wavebands to draw correlations between the high- resoluti…
Globular Cluster Luminosity Functions and the Hubble Constant From WFPC2 Imaging: The Giant Elliptical NGC 4365
Forbes, Duncan A.
The turnover, or peak, magnitude in a galaxy's globular cluster luminosity function (GCLF) may provide a standard candle for an independent distance estimator. Here we examine the GCLF of the giant elliptical NGC 4365 using photometry of ~350 globular clusters from the Hubble Space Telescope's Wide Field and Planetary Camera 2 (WFPC2). The WFPC2 d…