Search Publications
Hubble Space Telescope Images of Stephan's Quintet: Star Cluster Formation in a Compact Group Environment
Charlton, Jane C.; Whitmore, Bradley C.; Gallagher, Sarah C. +2 more
Analysis of Hubble Space Telescope Wide Field Planetary Camera 2 images of Stephan's Quintet, Hickson Compact Group 92, yielded 115 candidate star clusters (with V-I<1.5). Unlike in merger remnants, the cluster candidates in Stephan's Quintet are not clustered in the inner regions of the galaxies; they are spread over the debris and surrounding…
New Photometry for the Intermediate-Age Large Magellanic Cloud Globular Cluster NGC 2121 and the Nature of the LMC Age Gap
Rich, R. Michael; Shara, Michael M.; Zurek, David
We report new photometry for the cluster NGC 2121 in the Large Magellanic Cloud, which shows a prominent hydrogen core exhaustion gap at the turnoff and a descending subgiant branch reminiscent of Galactic open clusters. We achieve an excellent fit using the Girardi isochrones, finding an age of 3.2+/-0.5 Gyr, with [Fe/H]=-0.6+/-0.2. The isochrone…
M31 Globular Clusters in the Hubble Space Telescope Archive. I. Cluster Detection and Completeness
Huchra, John P.; Barmby, Pauline
Globular clusters at the distance of M31 have apparent angular sizes of a few arcseconds. While many M31 globular clusters have been detected and studied from ground-based images, the high spatial resolution of the Hubble Space Telescope (HST) allows much more robust detection and characterization of star cluster properties. We present the results…
The Nonstellar Infrared Continuum of Seyfert Galaxies
Simpson, Chris; Alonso-Herrero, Almudena; Quillen, Alice C. +2 more
JHKL'M (1-5 µm) imaging of a sample of Seyfert 2 galaxies is presented. We have performed an accurate estimate of the near-infrared nonstellar nuclear fluxes. We confirm that the near-infrared nuclear continuum between 1 and 2.2 µm of some Seyfert 2s is dominated by stellar emission, whereas the continuum emission at longer wavelengths…
Hubble Space Telescope WFPC2 Imaging of Cassiopeia A
Chevalier, Roger A.; Borkowski, Kazimierz J.; van den Bergh, Sidney +4 more
The young galactic supernova remnant Cassiopeia A was imaged with Wide Field Planetary Camera 2 (WFPC2) aboard the Hubble Space Telescope through filters selected to capture the complete velocity range of the remnant's main shell in several emission lines. The primary lines detected, along with the specific WFPC2 filters used, were [O III] λλ4959,…
Speckle Interferometry of New and Problem Hipparcos Binaries. II. Observations Obtained in 1998-1999 from McDonald Observatory
Mason, Brian D.; Hartkopf, William I.; Holdenried, Ellis R. +1 more
The Hipparcos satellite made measurements of over 9734 known double stars, 3406 new double stars, and 11,687 unresolved but possible double stars. The high angular resolution afforded by speckle interferometry makes it an efficient means to confirm these systems from the ground, which were first discovered from space. Because of its coverage of a …
Homogenization of the Stellar Population along Late-Type Spiral Galaxies
dos Anjos, S.; Gadotti, D. A.
We present a study of the broadband UBV color profiles for 257 Sbc barred and nonbarred galaxies, using photoelectric aperture photometry data from the literature. Using robust statistical methods, we have estimated the color gradients of the galaxies, as well as the total and bulge mean colors. A comparative photometric study using CCD images was…
Damped Lyα Absorption from a Nearby Low Surface Brightness Galaxy
Bowen, David V.; Tripp, Todd M.; Jenkins, Edward B.
Ground-based and Hubble Space Telescope (HST) images of the nearby galaxy SBS 1543+593 (z=0.009) show it to be a low surface brightness (LSB) galaxy with a central surface brightness µB(0)=23.2 mag arcsec-2 and scale length 0.9 h-1100 kpc, values typical for the local LSB galaxy population. The gal…
Variable Stars in the Unusual, Metal-Rich, Globular Cluster NGC 6441
Pritzl, Barton J.; Smith, Horace A.; Sweigart, Allen V. +1 more
We have undertaken a search for variable stars in the metal-rich globular cluster NGC 6441 using time-series BV photometry. The total number of variables found near NGC 6441 has been increased to ~104, with 48 new variables being found in this survey. A significant number of the variables are RR Lyrae stars (~46), most of which are probable cluste…
A Dynamical Mass Constraint for Pre-Main-Sequence Evolutionary Tracks: The Binary NTT 045251+3016
Latham, David W.; Mazeh, Tsevi; Prato, L. +6 more
We present an astrometric-spectroscopic orbital solution for the pre-main-sequence binary NTT 045251+3016. Interferometric observations with the HST Fine Guidance Sensor No. 3 allowed stellar separations as small as 14 mas to be measured. Optical spectra provided 58 radial velocity measurements of the primary star, and near-infrared spectra provid…