Search Publications
The Distribution of Nearby Stars in Velocity Space Inferred from HIPPARCOS Data
Dehnen, Walter
The velocity distribution f(v) of nearby stars is estimated, via a maximum likelihood algorithm, from the positions and tangential velocities of a kinematically unbiased sample of 14,369 stars observed by the Hipparcos satellite. The distribution f shows rich structure in the radial and azimuthal motions, v_R and v_phi, but not in the vertical vel…
High-z Lyalpha Emitters. I. A Blank-Field Search for Objects near Redshift Z = 3.4 in and around the Hubble Deep Field and the Hawaii Deep Field SSA 22
Cowie, Lennox L.; Hu, Esther M.
We present deep narrowband (lambda = 5390 Å, Deltalambda = 77 Å) and multicolor observations of the Hubble Deep Field and the Hawaii Deep Field SSA 22 obtained with the LRIS instrument at the 10 m Keck II Telescope. It is shown that there is a substantial population of galaxies at z ~ 3.4 that can be selected by Lyalpha emission. Comparison with c…
Spiral Galaxies with WFPC2. II. The Nuclear Properties of 40 Objects
Carollo, C. M.; Stiavelli, M.; Mack, J.
We report the analysis of Hubble Space Telescope Wide Field Planetary Camera 2 F606W images of 40 spiral galaxies belonging to the sample introduced in Paper I, where 35 other targets were discussed. We describe the optical morphological properties of the new 40 galaxies, derive the surface brightness profiles for 25 of them, and present the resul…
Optical-Infrared Spectral Energy Distributions of Z > 2 Lyman Break Galaxies
Sawicki, Marcin; Yee, H. K. C.
Broadband optical and IR spectral energy distributions are determined for spectroscopically confirmed z > 2 Lyman break objects in the Hubble Deep Field (HDF). These photometric data are compared with spectral synthesis models which take into account the effects of metallicity and of internal reddening due to dust. It is found that, on average,…
The Luminosity Function and Initial Mass Function in the Galactic Bulge
Grillmair, Carl J.; Holtzman, Jon A.; Lynds, Roger +5 more
We present deep photometry obtained with the Hubble Space Telescope in a field in Baade's window in the Galactic bulge. We derive a luminosity function down to I ~ 24.3, or V ~ 27.5, corresponding to M ~ 0.3 M_⊙. The luminosity function from the turnoff down to this level appears remarkably similar to that observed in the solar neighborhood. We de…
M32 +/- 1
Lauer, Tod R.; Ajhar, Edward A.; Faber, S. M. +2 more
Multicolor HST WFPC2 images are used to study the central structure of the three Local Group galaxies M31, M32, and M33. PSF deconvolution and modeling of image aliasing are required to recover accurate brightness profiles within r < 0.5". The data present a study in contrasts that suggests different evolutionary histories. In M31, the nucleus …
Externally Illuminated Young Stellar Environments in the Orion Nebula: Hubble Space Telescope Planetary Camera and Ultraviolet Observations
Johnstone, Doug; Bally, John; Sutherland, Ralph S. +1 more
We present new 0.05" resolution (22 AU) narrowband Hubble Space Telescope Planetary Camera images of externally illuminated young stellar objects embedded in the Orion Nebula. We also present 0.02" resolution (9 AU) UV images of seven externally illuminated protostellar environments and the first UV spectra that cover the spectral range between 14…
Radio Emission from Galaxies in the Hubble Deep Field
Fomalont, E. B.; Windhorst, R. A.; Richards, E. A. +2 more
We report on sensitive radio observations made with the VLA at 8.5 GHz centered on the Hubble Deep Field (HDF). We collected data in the A, CnB, C, DnC, and D configurations corresponding to angular resolutions ranging from 0.3" to 10". We detected 29 radio sources in a complete sample within 4.6‧ of the HDF center and above a flux density limit o…
The ACT Reference Catalog
Urban, S. E.; Wycoff, G. L.; Corbin, T. E.
The US Naval Observatory has completed the compilation of the ACT Reference Catalog, containing 988,758 stars covering the entire sky. The motivation behind the ACT was to provide accurate proper motions for the majority of the stars in the Tycho Catalogue. To do this, positions from new reductions of the Astrographic Catalogue (AC 2000) were comb…
The Ultraviolet Spectra of LINERs: A Comparative Study
Filippenko, Alexei V.; Ho, Luis C.; Maoz, Dan +3 more
Imaging studies have shown that ~25% of LINER galaxies display a compact nuclear UV source. As part of a program to study the nature of LINERs and their connection to the active galaxy phenomenon, we compare the Hubble Space Telescope UV (1150-3200 Å) spectra of seven such UV-bright LINERs. Data for three of the galaxies (NGC 404, 4569, and 5055) …