Search Publications
A Hubble Space Telescope Survey for Resolved Companions of Planetary Nebula Nuclei
Bond, Howard E.; Ciardullo, Robin; Fullton, Laura K. +3 more
We report the results of a Hubble Space Telescope ``snapshot'' survey aimed at finding resolved binary companions of the central stars of Galactic planetary nebulae (PNe). Using the the Wide Field and Planetary Camera and Wide Field Planetary Camera 2, we searched the fields of 113 PNe for stars whose close proximity to the central star suggests a…
Radii and Effective Temperatures for G, K, and M Giants and Supergiants
Kulkarni, S. R.; Palmer, D.; van Belle, G. T. +13 more
Interferometrically determined angular diameters obtained at the Palomar Testbed Interferometer (PTI) for 69 giant and supergiant stars are presented. Spectral types of the 59 giant stars generally lie between G6 and M6, although a B7 giant is included; the nine bright giants and supergiants have spectral types between F5 and M5. Comparison of the…
On the origin of solar metric type II bursts
Howard, Russell A.; Webb, David F.; Cliver, Edward W.
The vast majority of solar flares are not associated with metric Type II radio bursts. For example, for the period February 1980-July 1982, corresponding to the first two and one-half years of the Solar Maximum Mission, 95% of the ∼2500 flares with peak >25 keV count rates >100 c s−1lacked associated Type II emission. Even the ∼36…
Globular Cluster Systems. I. V-I Color Distributions
Gebhardt, Karl; Kissler-Patig, Markus
We have compiled data for the globular cluster systems of 50 galaxies from the Hubble Space Telescope Wide Field Planetary Camera 2 archive, of which 43 are type S0 or earlier. In this paper, we present the data set and derive the V-I color distributions. We derive the first four moments of the color distributions, as well as a measure for their n…
The Star Formation History of the Local Group Dwarf Galaxy Leo I
Freedman, Wendy L.; Aparicio, Antonio; Gallart, Carme +2 more
We present a quantitative analysis of the star formation history (SFH) of the Local Group dSph galaxy Leo I, from the information in its Hubble Space Telescope [(V-I),I] color-magnitude diagram (CMD). It reaches the level of the oldest main-sequence turnoffs, and this allows us to retrieve the SFH in considerable detail. The method we use is based…
The Formation and Evolution of Candidate Young Globular Clusters in NGC 3256
Zepf, Stephen E.; Freeman, Kenneth C.; Sharples, Ray M. +2 more
We present images of the recent galaxy merger NGC 3256 obtained with the Wide Field Planetary Camera 2 of the Hubble Space Telescope in B and I filters. We show that there is a large population of more than 1000 compact, bright, blue objects in this galaxy within the 7 kpcx7 kpc region studied. These objects have sizes, colors, and luminosities li…
Helioseismic Constraints on the Structure of the Solar Tachocline
Thompson, M. J.; Christensen-Dalsgaard, J.; Schou, J. +4 more
This paper presents a series of helioseismic inversions aimed at determining with the highest possible confidence and accuracy the structure of the rotational shear layer (the tachocline) located beneath the base of the solar convective envelope. We are particularly interested in identifying features of the inversions that are robust properties of…
The Age of β Pictoris
Barrado y Navascués, David; Stauffer, John R.; Song, Inseok +1 more
We have reanalyzed data for the proposed moving group associated with β Pictoris in order to determine if the group (or part of it) is real and, if so, to derive an improved age estimate for β Pic. By using new, more accurate proper motions from PPM and Hipparcos and a few new radial velocities, we conclude that on kinematic grounds, most of the p…
Plasma Properties in Coronal Holes Derived from Measurements of Minor Ion Spectral Lines and Polarized White Light Intensity
Fineschi, Silvano; Kohl, John L.; Raymond, John C. +5 more
Recent observations of the Lyα λ1216, Mg X λ625, and O VI λ1038 spectral lines carried out with the Ultraviolet Coronagraph Spectrometer (UVCS) on board SOHO at distances in the range 1.35-2.1 RS in the northern coronal hole are used to place limits on the turbulent wave motions of the background plasma and the thermal motions of the pr…
Revisiting Hipparcos data for pre-main sequence stars
Arenou, F.; Robichon, N.; Bertout, C.
We cross-correlate the Herbig & Bell and Hipparcos Catalogues in order to extract the results for young stellar objects (YSOs). We compare the distances of individual young stars and the distance of their presumably associated molecular clouds, taking into account post-Hipparcos distances to the relevant associations and using Hipparcos interm…