Search Publications
The Complex Kinematics of the Neutral Hydrogen Associated with I ZW 18
Salzer, John J.; Haynes, Martha P.; van Zee, Liese +1 more
We present the results of high velocity (1.3 km s^-1 channels) and high spatial (~5", or ~250 pc at the distance of I Zw 18) resolution H i synthesis observations of the blue compact dwarf galaxy I Zw 18 to investigate the link between its unique evolutionary history and the neutral gas distribution and kinematics. The H i distribution is extensiv…
Evidence for a 3 X 10^8 M_⊙ Black Hole in NGC 7052 from Hubble Space Telescope Observations of the Nuclear Gas Disk
van den Bosch, Frank C.; van der Marel, Roeland P.
We present a Hubble Space Telescope (HST) study of the nuclear region of the E4 radio galaxy NGC 7052, which has a nuclear disk of dust and gas. The Second Wide Field and Planetary Camera (WFPC2) was used to obtain B, V, and I broadband images and an Hα + [N II] narrowband image. The images yield the stellar surface brightness profile, the optical…
WFPC2 Observations of Star Clusters in the Magellanic Clouds. II. The Oldest Star Clusters in the Small Magellanic Cloud
Sarajedini, Ata; Mighell, Kenneth J.; French, Rica S.
We present our analysis of archival Hubble Space Telescope Wide Field Planetary Camera 2 (WFPC2) observations in F450W (~B) and F555W (~V) of the intermediate-age populous star clusters NGC 121, NGC 339, NGC 361, NGC 416, and Kron 3 in the Small Magellanic Cloud. We use published photometry of two other SMC populous star clusters, Lindsay 1 and Li…
Wide Field Planetary Camera 2 Observations of Leo A: A Predominantly Young Galaxy within the Local Group
Saha, A.; Gallagher, J. S.; Cole, A. A. +6 more
The unprecedented detail of the Wide Field Planetary Camera 2 (WFPC2) color-magnitude diagrams (CMDs) of the resolved stellar population of Leo A presented here allows us to determine a new distance and an accurate star formation history for this extremely metal-poor Local Group dwarf irregular galaxy. From the position of the red clump, the heliu…
FLIERs and Other Microstructures in Planetary Nebulae. IV. Images of Elliptical PNs from the Hubble Space Telescope
Perinotto, Mario; Balick, Bruce; Hajian, Arsen R. +3 more
We report new results from high spatial resolution Wide Field Planetary Camera 2 imaging studies of ``FLIERs'' and other microstructures in the planetary nebulae NGC 3242, 6826, 7009, and 7662. Most FLIERs have head-tail morphologies, with the tails pointing outward from the nucleus. Ionization gradients that decrease with distance from the nebula…
Wide Field Planetary Camera 2 Imaging of the Globular Cluster System of the S0 Galaxy NGC 3115
Kundu, Arunav; Whitmore, Bradley C.
Using the Wide Field Planetary Camera 2 on board the Hubble Space Telescope we have identified 144 globular cluster candidates in the inner region of the S0 galaxy NGC 3115. The color distribution of the globular clusters is bimodal, with a blue peak at V-I = 0.96 mag and a red peak at V-I = 1.17 mag. There are roughly equal number of blue and red…
HIPPARCOS Subdwarf Parallaxes: Metal-rich Clusters and the Thick Disk
Reid, Neill
We have used main-sequence fitting to calibrate the distances to the globular clusters NGC 6397, M5, NGC 288, M71, and 47 Tucanae, matching the cluster photometry against data for subdwarfs with precise Hipparcos parallax measurements and accurate abundance determinations. Both the cluster and subdwarf abundance scales are tied to high-resolution …
A Z = 5.34 Galaxy Pair in the Hubble Deep Field
Dey, Arjun; Bunker, Andrew; Spinrad, Hyron +5 more
We present spectrograms of the faint V-drop (V_606 = 28.1, I_814 = 25.6) galaxy pair HDF 3-951.1 and HDF 3-951.2 obtained at the Keck II Telescope. In a recent study, Fernández-Soto, Lanzetta, & Yahil derive a photometric redshift of z_ph=5.28^+0.34_-0.41 (2 sigma) for these galaxies; our integrated spectrograms show a large and abrupt discont…
Hubble Space Telescope Wide Field Planetary Camera 2 Observations of eta Carinae
Frank, Adam; Davidson, Kris; Bally, John +3 more
Hubble Space Telescope (HST) continuum and emission-line images of eta Carinae obtained with the Planetary Camera (PC) of the Wide Field Planetary Camera 2 show a startling wealth of detailed structure in the expanding Homunculus Nebula and outer debris field. Using a combination of dithering and image deconvolutions, we have achieved a resolution…
The AC 2000: The Astrographic Catalogue on the System Defined by the HIPPARCOS Catalogue
Urban, S. E.; Wycoff, G. L.; Martin, J. C. +4 more
The AC 2000 is a positional catalog of 4,621,836 stars covering the entire sky. The average epoch of position is 1907. The data are from the images measured and published as part of the Astrographic Catalogue (AC). The positions are on the system defined by the Hipparcos Catalogue, having originally been reduced plate-by-plate using the Astrograph…