Search Publications
VRI CCD Photometry of Supergiant Stars in the Barred Galaxies NGC 925 and NGC 1637
Davidge, T. J.; Sohn, Young-Jong
V, R, and I CCD images obtained with the Canada-France-Hawaii Telescope are used to investigate the bright stellar content of the barred spiral galaxies NGC 925 and NGC 1637. Not counting objects located in H ii regions, we detect 295 supergiants in NGC 925 and 266 in NGC 1637. Comparisons with theoretical isochrones indicate that massive star for…
Hubble Space Telescope Fine Guidance Sensor Astrometry of the Low-Mass Binary L722-22
Hershey, John L.; Taff, L. G.
The M dwarf star L722-22 (LHS 1047, GJ 1005) was discovered to be a binary in 1979. Analysis of ground-based data indicated a mass near 0.06 M_⊙ for the secondary star, well below the nominal stellar mass limit of 0.08 M_⊙. The close, faint binary was near the limit for ground-based astrometry and was approved for Hubble Space Telescope Fine Guida…
A Color-Magnitude Diagram for a Globular Cluster in the Giant Elliptical Galaxy NGC 5128
Harris, William E.; Harris, Gretchen L. H.; Poole, G. B.
The Hubble Space Telescope has been used to obtain WFPC2 V, I photometry for a large sample of stars in the outer halo of the giant elliptical NGC 5128 (d ~= 4 Mpc). The target region is located at a projected distance 21 kpc from the center of NGC 5128. The globular cluster N5128-C44, at the center of the Planetary Camera field, is well enough re…
Possible High-Redshift, Low-Luminosity Active Galactic Nuclei in the Hubble Deep Field
MacAlpine, Gordon M.; Jarvis, R. Michael
In the Hubble Deep Field (HDF), 12 candidate sources of high-redshift (z > 3.5) active galactic nuclei (AGN) have been identified. The color selection criteria were established by passing spectra of selected quasars and Seyfert galaxies (appropriately redshifted and modified for ``Lyman forest'' absorption), as well as stars, observed normal an…
ISOCAM Molecular Hydrogen Images of the Cepheus E Outflow
Garnavich, Peter M.; Molinari, Sergio; Noriega-Crespo, Alberto
The physical characteristics of the Cepheus E ``embedded'' outflow are analyzed using ISOCAM images in the v = 0-0 S(5) 6.91 µm and S(3) 9.66 µm molecular hydrogen lines. We find that the morphology of the Cep E outflow in the ground vibrational H_2 lines is similar to that in the near-infrared v = 1-0 2.12 µm line. At these mid-…
Deep Hubble Space Telescope Galaxy and Pair Counts as Tests of Merger History
Keel, William C.; Wu, Wentao
We consider the use of counts of faint galaxy pairs as tests of the role of merging in galaxy evolution, using both simulations and Hubble Space Telescope (HST) data in comparison with models incorporating a range in the evolution of merger rate. Artificial data, including simulation of the surface-brightness selection effects implicit in HST imag…
Stellar Populations and Variable Stars in the Core of the Globular Cluster M5
Drissen, Laurent; Shara, Michael M.
We report the discovery of a variable blue straggler in the core of the globular cluster M5, based on a 12 hr-long series of images obtained with the Planetary Camera aboard the Hubble Space Telescope. In addition, we present the light curves of 28 previously unknown or poorly studied large-amplitude variable stars (all but one are RR Lyrae stars)…
The Metal Absorption Systems of the Hubble Deep Field South QSO
Savaglio, Sandra
The Hubble Deep Field South (HDFS) has been recently selected, and the observations are planned for 1998 October. We present a high-resolution (FWHM ~= 14 km s^-1) spectrum of the quasar J2233-606 (z_em ~= 2.22), which is located 5.1‧ east of the HDFS. The spectrum obtained with the New Technology Telescope redward of the Lyalpha emission line cov…
Surface Brightness of Starbursts at Low and High Redshifts
Schneider, Donald P.; Weedman, Daniel W.; Wolovitz, Jeffrey B. +1 more
Observations in the rest-frame ultraviolet from various space missions are used to define the nearby starburst regions having the highest surface brightness on scales of several hundred parsecs. The bright limit is found to be 6 x 10^-16 ergs cm^-2 s^-1 Å^-1 arcsec^-2 for rest-frame wavelength of 1830 Å. Surface brightness in the brightest pixel i…
A Search for the Optical Counterpart of the Luminous X-Ray Source in NGC 6652
Anderson, Scott F.; Margon, Bruce; Deutsch, Eric W.
We examine images of the field of X1832-330, the luminous (L_X ~ 10^36 ergs s^-1) X-ray burst source near the center of the globular cluster NGC 6652, in order to identify the optical counterpart for further study. U and B ground-based images allow us to set a limit M_B_0 >~ 3.5 for the counterpart at the time of those observations, provided th…