Search Publications
Planetary Camera Observations of NGC 1275: Discovery of a Central Population of Compact Massive Blue Star Clusters
Holtzman, J. A.; Faber, S. M.; Ewald, S. P. +10 more
We have discovered a population of bright blue pointlike sources within 5 kpc of the nucleus of NGC 1275 using HST Planetary Camera observations. The typical object has M_v_ ~ - 12 to - 14 (H_0_ = 75 km s^-1^ Mpc^-1^ ); the brightest has M_v_ ~ - 16. They are all blue, with V - R <~ 0.3. The color distribution and lack of excess Hα emission are…
NGC 1705. I. Stellar Populations and Mass Loss Via A Galactic Wind
Freeman, K. C.; Meurer, Gerhardt R.; Dopita, Michael A. +1 more
We present a detailed multi-waveband study of the galaxy NGC 1705. The data include optical and ultraviolet spectroscopy, optical and infrared photoelectric aperture photometry, narrowband and broadband images, H I spectra, and data from the IRAS point source catalog. NGC 1705 is shown to be a nearby (D~5 Mpc for H_0_ = 75 km s^-1^ Mpc^-1^) nuclea…
Planetary Camera Observations of the M87 Stellar CUSP
Schneider, Donald P.; Lauer, Tod R.; Faber, S. M. +11 more
Analysis of V and I band HST Planetary Camera images of the giant elliptical galaxy M87 show that its central starlight distribution is consistent with the black hole M_black hole_ = 2.6 X 10^9^ M_sun_ cusp model proposed for M87 by Young et al, [ApJ, 221,721(1978)]. A combined approach of image deconvolution and modeling is used to investigate th…
Planetary Camera Observations of the Central Parsec of M32
Lauer, Tod R.; Faber, S. M.; Currie, Douglas G. +8 more
Analysis of V band HST Planetary Camera images of the elliptical galaxy M32 shows that its nucleus is extremely dense and remains unresolved at even the HST diffraction limit. A combined approach of image deconvolution and model fitting is used to investigate the starlight distribution into limiting radii of 0.04" (0.14 pc at 700 kpc). The logarit…
Hubble Space Telescope Planetary Camera Images of R136
Lauer, Tod R.; Faber, S. M.; Holtzman, Jon A. +9 more
The Planetary Camera of the Hubble Space Telescope has been used to obtain broad and narrowband images of R136, the core of the massive star cluster 30 Doradus in the Large Magellanic Cloud. R136a, the brightest component of R136, is shown to have at least 12 separate components, including the eight originally identified by speckle interferometry.…
Globular Cluster Photometry With the Hubble Space Telescope. I. Description of the Method and Analysis of the Core of 47 TUC
Schneider, Donald P.; Yanny, Brian; Bahcall, John N. +1 more
Accurate photometry for individual post-main-sequence stars in the core of the Galactic globular cluster 47 Tuc is presented and analyzed using an empirical point spread function model and Monte Carlo simulations. A V vs. V-I color-magnitude diagrams is constructed which shows several distinct stellar types, including RGB and HB stars. Twenty-four…
Hubble Space Telescope Wide Field Camera Imaging of the Gravitational Lens 2237+0305
Schneider, Donald P.; Rix, Hans-Walter; Bahcall, John N.
Hubble Space Telescope Wide Field Camera images of the gravitational lens 2237+0305 in the F336W ("U") and F702W ("A") filters are used to construct models of the system. Positions for the four quasar images, accurate to +/-0.015", and relative magnitudes in U and R, accurate to +/-0.06 and 0.04 mag respectively, are determined. The upper limits o…
On the Nature of the Symbiotic Binary AX Persei
Mikolajewska, Joanna; Kenyon, Scott J.
Photometric and spectroscopic observations of the symbiotic binary AX Persei are presented. This system contains a red giant that fills its tidal lobe and transfers material into an accretion disk surrounding a low-mass main-sequence star. The stellar masses - 1 solar mass for the red giant and about 0.4 solar mass for the companion - suggest AX P…
The Quantative Assessment of UV Extinction Derived From IUE Data of Giants and Supergiants
Sembach, Kenneth R.; Cardelli, Jason A.; Mathis, John S.
It is shown here that the UV interstellar extinction towards hot luminous stars can be determined as accurately as for hot main-sequence stars. An atlas of IUE dereddened fluxes is presented for 13 lightly reddened stars within the 1160-3125 A range. The fluxes of these stars how absorption line strengths that allow a rather accurate determination…
Dynamical Evolution Effects on the Hot Stellar Populations in Globular Clusters
Piotto, Giampaolo; Djorgovski, S.
Results of a study of FUV properties of Galactic globular clusters are presented. The spatially resolved spectra measured with the IUE satellite are used to find indications of color gradients in two clusters with the postcore-collapse (PCC) morphology, NGC 6752 and NGC 7099, but not in the case of NTGC 6093, a cluster with the classical King-mode…