Search Publications
Kinematics of the Nuclear Ionized Gas in the Radio Galaxy M84 (NGC 4374)
Kimble, R.; Kraemer, S.; Green, R. F. +17 more
We present optical long-slit spectroscopy of the nucleus of the nearby radio galaxy M84 (NGC 4374 = 3C 272.1) obtained with the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope. Our spectra reveal that the nuclear gas disk seen in the Wide Field Planetary Camera 2 imaging by Bower et al. is rotating rapidly. The velocity curv…
The EC 14026 stars - VIII. PG 1336-018: a pulsating sdB star in an HWVir-type eclipsing binary
O'Donoghue, D.; Kilkenny, D.; Lynas-Gray, A. E. +2 more
The sdB star PG 1336-018 is found to be a very short-period eclipsing binary system, remarkably similar to the previously unique system HW Vir. In addition, and unlike HW Vir, the sdB star in the PG 1336 system shows rapid oscillations of the type found in the recently discovered sdB pulsators, or EC 14026 stars. The orbital period, 0.101 0174 d, …
Spectral analyses of PG 1159 star: constraints on the GW Virginis pulsations from HST observations
Dreizler, S.; Heber, U.
We present the results of a quantitative analysis of UV and optical spectra of nine PG 0122+200ls, very hot hydrogen-deficient [pre-] white dwarfs, by means of line blanketed NLTE model atmospheres. Four programme stars constitute the GW Vir variables, a class of non-radial g-mode pulsators. Precise effective temperatures, carbon, nitrogen and oxy…
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…
Early-Type Galaxies in the Hubble Deep Field: The Star Formation History
Franceschini, Alberto; Bressan, Alessandro; Fasano, Giovanni +4 more
We have investigated the properties of a complete K-band selected sample of 35 elliptical and S0 galaxies brighter than K = 20.15 mag in the Hubble deep field, as representative of the field galaxy population. This sample has been derived from deep K-band image by the KPNO-IRIM camera, by applying a rigorous morphological classification scheme bas…
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 …
The Resolved Stellar Population of the Poststarburst Galaxy NGC 1569
Leitherer, Claus; Clampin, Mark; Nota, Antonella +4 more
We present Hubble Space Telescope (HST) Wide Field Planetary Camera 2 (WFPC2) photometry of the resolved stellar population in the poststarburst galaxy NGC 1569. The color-magnitude diagram (CMD) derived in the F439W and F555W photometric bands contains ~2800 stars with a photometric error of <=0.2 mag down to mF439, mF555…
New Constraints on the Continuum Emission Mechanism of Active Galactic Nuclei: Intensive Monitoring of NGC 7469 in the X-Ray and Ultraviolet
Malkan, M. A.; Nandra, K.; Clavel, J. +5 more
We have undertaken near-continuous monitoring of the Seyfert 1 galaxy NGC 7469 in the X-ray with RXTE over a ~30 day baseline. The source shows strong variability with a root mean square (rms) amplitude of ~16% and peak-to-peak variations of a factor of order 2. Simultaneous data over this period were obtained in the ultraviolet (UV) using IUE, ma…
Hubble Space Telescope Goddard High Resolution Spectrograph Observations of the Be + sdO Binary φ Persei
Gies, Douglas R.; Peters, Geraldine J.; Ferrara, Elizabeth C. +4 more
Mass transfer during the evolution of intermediate-mass stars in a close binary system can result in a rejuvenated and spun-up secondary star (which may appear as a rapidly rotating Be star) orbiting an unseen, stripped-down, remnant companion. One of the best candidates for such a system is the long-period (127 days) binary φ Per. Here we present…