Search Publications
SPICES II: Optical and Near-Infrared Identifications of Faint X-Ray Sources from Deep Chandra Observations of Lynx
Dey, Arjun; Rosati, Piero; Stanford, S. A. +10 more
We present our first results on field X-ray sources detected in a deep, 184.7 ks observation with the Advanced CCD Imaging Spectrometer (ACIS-I) on the Chandra X-Ray Observatory. The observations target the Lynx field (α=08h48m, δ=+44°54') of SPICES, the Spectroscopic Photometric Infrared-Chosen Extragalactic Survey, which co…
Tip of the Red Giant Branch Distances to NGC 4214, UGC 685, and UGC 5456
MacKenty, John W.; Maíz-Apellániz, Jesús; Cieza, Lucas
We have used WFPC2 VRI observations to calculate the distances to three nearby galaxies, NGC 4214, UGC 685, and UGC 5456, using the tip of the red giant branch method. Our values for NGC 4214 (2.94+/-0.18 Mpc) and UGC 685 (4.79+/-0.30 Mpc) are the most precise measurements of the distances to these objects ever made. For UGC 5456 the data do not a…
The Luminosity Functions of Old and Intermediate-Age Globular Clusters in NGC 3610
Kundu, Arunav; Whitmore, Bradley C.; Schweizer, François +1 more
The Wide Field Planetary Camera 2 on board the Hubble Space Telescope (HST) has been used to obtain high-resolution images of NGC 3610, a dynamically young elliptical galaxy in a group environment. These observations supersede shorter, undithered HST observations in which an intermediate-age population of globular clusters was discovered. The new …
Computing the Parallax of the Pleiades from the Hipparcos Intermediate Astrometry Data: An Alternative Approach
Makarov, Valeri V.
The inconsistency between the mean parallax of the Pleidaes open cluster from the Hipparcos catalog and that obtained from the stellar evolution theory and photometric measurements is probed by recomputing the Hipparcos data in a different way that reduces the propagation of the along-scan attitude errors. This is achieved by coupling observations…
The Puzzle of the Polar Structure in NGC 4650A
Freeman, K. C.; De Lucia, G.; Gallagher, J. S., III +3 more
This work presents new surface photometry and two-dimensional modeling of the light distribution of the polar ring galaxy NGC 4650A, based on near-infrared (NIR) observations and high-resolution optical imaging acquired during the Hubble Heritage program. The NIR and optical integrated colors of the S0 galaxy and the polar ring and their scale par…
Analysis of the First Disk-resolved Images of Ceres from Ultraviolet Observations with the Hubble Space Telescope
Parker, Joel Wm.; Stern, S. Alan; Thomas, Peter C. +5 more
We present Hubble Space Telescope Faint Object Camera observations of the asteroid 1 Ceres at near-, mid-, and far-UV wavelengths (λ=3636, 2795, and 1621 Å, respectively) obtained on 1995 June 25. The disk of Ceres is well resolved for the first time, at a scale of ~50 km. We report the detection of a large, ~250 km diameter surface feature for wh…
The Ratio of Blue to Red Supergiants in Sextans A from Hubble Space Telescope Imaging
Skillman, Evan D.; Dohm-Palmer, Robbie C.
We have examined the ratio of blue to red supergiants (B/R) in the dwarf irregular galaxy Sextans A. The supergiants were identified in previously published stellar photometry measured from Hubble Space Telescope imaging. The high-resolution imaging and low-dust environment provided high photometric accuracy such that the main sequence and blue he…
The Dwarf Spheroidal Companions to M31: WFPC2 Observations of Andromeda III
Da Costa, G. S.; Armandroff, T. E.; Caldwell, Nelson
The Hubble Space Telescope Wide Field Planetary Camera 2 has been used to image Andromeda III, a dwarf spheroidal (dSph) companion to M31. The resulting color-magnitude diagrams (CMDs) reveal for the first time the morphology of the horizontal branch (HB) in this dwarf galaxy. We find that like Andromeda I and Andromeda II, and like most of the Ga…
The Angular Expansion and Distance of the Planetary Nebula BD +30°3639
Borkowski, Kazimierz J.; Harrington, J. Patrick; Li, Jianyang
The WFPC2 camera aboard the Hubble Space Telescope was used to obtain images of the planetary nebula BD +30°3639 at two epochs separated by 5.663 yr. The expansion of the nebula in the Hα and [N II] bands has been measured using several methods. Detailed expansion maps for both emission lines were constructed from nearly 200 almost independent fea…
A Three-dimensional Map of Titan's Tropospheric Haze Distribution Based on Hubble Space Telescope Imaging
McKay, Christopher P.; Griffith, Caitlin A.; Noll, Keith +2 more
We use Hubble Space Telescope (HST) images of Titan obtained in late 1996 to determine a three-dimensional map of haze optical depth in Titan's atmosphere. These images, taken at six wavelengths from 888 to 953 nm, probe Titan's atmosphere at various altitudes ranging from the surface to roughly 100 km. We solve for the total haze optical depths t…