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Preplanetary Nebulae: A Hubble Space Telescope Imaging Survey and a New Morphological Classification System
Sahai, Raghvendra; Sánchez Contreras, Carmen; Morris, Mark +1 more
Using the Hubble Space Telescope (HST), we have carried out a survey of candidate preplanetary nebulae (PPNs). We report here our discoveries of objects having well-resolved geometric structures, and we use the large sample of PPNs now imaged with HST (including previously studied objects in this class) to devise a comprehensive morphological clas…
The Compact, Conical, Accretion-Disk Warm Absorber of the Seyfert 1 Galaxy NGC 4051 and Its Implications for IGM-Galaxy Feedback Processes
Elvis, Martin; Nicastro, Fabrizio; Mathur, Smita +4 more
Using a 100 ks XMM-Newton exposure of NGC 4051, we show that the time evolution of the ionization state of the X-ray absorbers in response to the rapid and highly variable X-ray continuum constrains all the main physical and geometrical properties of an AGN ``warm absorber'' wind. The absorber consists of two different ionization components, with …
Deep GALEX Imaging of the COSMOS HST Field: A First Look at the Morphology of z ~ 0.7 Star-forming Galaxies
Aussel, H.; Sanders, D. B.; Ilbert, O. +34 more
We present a study of the morphological nature of redshift z~0.7 star-forming galaxies using a combination of HST ACS, GALEX, and ground-based images of the COSMOS field. Our sample consists of 8146 galaxies, 5777 of which are detected in the GALEX near-ultraviolet band (2310 Å or ~1360 Å rest frame) down to a limiting magnitude of 25.5 (AB), and …
Martian surface mineralogy from Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité on board the Mars Express spacecraft (OMEGA/MEx): Global mineral maps
Bibring, J. -P.; Gondet, B.; Langevin, Y. +5 more
After 2 years of operation the Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité (OMEGA) imaging spectrometer on board Mars Express has acquired data coverage of the Martian surface with spatial resolution varying between 300 m and 4.8 km, depending on the pericenter altitude of the spacecraft's elliptical orbit. We report the glob…
The innermost region of AGN tori: implications from the HST/NICMOS type 1 point sources and near-IR reverberation
Hönig, S. F.; Kishimoto, M.; Weigelt, G. +1 more
Spatially resolving the innermost region of the putative torus-like structure in an active galactic nucleus (AGN) is one of the main goals of high-spatial-resolution studies. This could be done in the near-IR observations of type 1 AGNs where we directly see the hottest dust grains in the torus. We discuss two critical issues in such studies. One …
Cryovolcanic features on Titan's surface as revealed by the Cassini Titan Radar Mapper
Soderblom, L. A.; Ostro, S. J.; West, R. D. +41 more
The Cassini Titan Radar Mapper obtained Synthetic Aperture Radar images of Titan's surface during four fly-bys during the mission's first year. These images show that Titan's surface is very complex geologically, showing evidence of major planetary geologic processes, including cryovolcanism. This paper discusses the variety of cryovolcanic featur…
A double main-sequence turn-off in the rich star cluster NGC 1846 in the Large Magellanic Cloud
Mackey, A. D.; Broby Nielsen, P.
We report on Hubble Space Telescope/ACS photometry of the rich intermediate-age star cluster NGC 1846 in the Large Magellanic Cloud, which clearly reveals the presence of a double main-sequence turn-off in this object. Despite this, the main-sequence, subgiant branch and red giant branch are all narrow and well defined, and the red clump is compac…
Hα Tail, Intracluster H II Regions, and Star Formation: ESO 137-001 in Abell 3627
Sun, M.; Donahue, M.; Voit, G. M.
We present the discovery of a 40 kpc Hα tail and at least 29 emission-line objects downstream of a star-forming galaxy, ESO 137-001, in the rich, nearby cluster A3627. The galaxy is known to possess a dramatic 70 kpc X-ray tail. The detected Hα tail coincides positionally with the X-ray tail. The Hα emission in the galaxy is sharply truncated on t…
A New Population of High-Redshift Short-Duration Gamma-Ray Bursts
Cenko, S. B.; Peterson, B. A.; Price, P. A. +23 more
The redshift distribution of the short-duration gamma-ray bursts (GRBs) is a crucial, but currently fragmentary, clue to the nature of their progenitors. Here we present optical observations of nine short GRBs obtained with Gemini, Magellan, and the Hubble Space Telescope. We detect the afterglows and host galaxies of two short bursts, and host ga…
Leo A: A Late-blooming Survivor of the Epoch of Reionization in the Local Group
Dolphin, Andrew E.; Skillman, Evan D.; Cole, Andrew A. +8 more
As part of a major program to use isolated Local Group dwarf galaxies as near-field probes of cosmology, we have obtained deep images of the dwarf irregular galaxy Leo A with the Advanced Camera for Surveys aboard the Hubble Space Telescope. From these images we have constructed a color-magnitude diagram (CMD) reaching apparent [absolute] magnitud…