Search Publications
η Carinae's Brightness Variations Since 1998: Hubble Space Telescope Observations of the Central Star
Martin, J. C.; Koppelman, M. D.
We have measured the brightness variations in η Carinae for the past 6 years using the Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph and Advanced Camera for Surveys. Unlike ground-based data, observations by the HST allow direct measurement of the brightness of the central star by resolving it from the surrounding bright ejecta…
The Ages of Dwarf Elliptical Galaxies
Schombert, James; Rakos, Karl
We present narrowband photometry of 91 dwarf elliptical galaxies in the Coma and Fornax Clusters taken with the Strömgren (uvby) filter system. Dividing the sample by dwarf morphology into nucleated (dEN) and nonnucleated (dE) dwarfs reveals two distinct populations of early-type systems based on integrated colors. The class of dEN galaxies are re…
Australia Telescope Compact Array Survey of Candidate Ultracompact and Buried H II Regions in the Magellanic Clouds
Johnson, Kelsey E.; Indebetouw, Rémy; Conti, Peter
We present a systematic survey for ultracompact (UC) H II regions in the Magellanic Clouds. Understanding the physics of massive star formation (MSF) is a critical astrophysical problem. The study of MSF began in our Galaxy with surveys of UC H II regions, but before now this has not been done for other galaxies. We selected candidates on the basi…
Ultracompact Dwarf Galaxies in Abell 1689: A Photometric Study with the Advanced Camera for Surveys
Ford, H. C.; Infante, L.; Zheng, W. +37 more
The properties of ultracompact dwarf (UCD) galaxy candidates in Abell 1689 (z=0.183) are investigated, based on deep high-resolution images from the Hubble Space Telescope Advanced Camera for Surveys. A UCD candidate has to be unresolved, have i<28 mag (MV<-11.5 mag), and satisfy color limits derived from Bayesian photometric reds…
Internal Velocities in the Orion Nebula: Large Radial Velocity Features
Hartigan, Patrick; O'Dell, C. R.; Doi, Takao
A map of high-velocity features in the 3'×5' central region of the Orion Nebula was created from slit spectra with a velocity resolution of 8 km s-1. We identified two new bipolar flows, Herbig-Haro (HH) 725 and HH 726, as well as a highly redshifted flow, HH 512. We also found multiple new high-velocity co-moving …
Hubble Space Telescope Imaging of Extraplanar Dust Structures in the Edge-On Spiral NGC 4217
Savage, Blair D.; Howk, J. Christopher; Thompson, Thomas W. J.
We present high-resolution (~ 0.1") B, V, and I images of the edge-on Sb galaxy NGC 4217 obtained with the Wide Field Planetary Camera 2 (WFPC2) on-board the Hubble Space Telescope (HST). We make use of these images to study extraplanar (z>0.4 kpc) dust structures visible in absorption against the background stellar light of the galaxy, similar…
Inner Polar Rings in Regular Lenticular Galaxies
Sil'chenko, O. K.; Afanasiev, V. L.
We have investigated a sample of S0 galaxies, mostly with circumnuclear dust lanes orthogonal to their major axes, chosen from Hubble Space Telescope Wide Field Planetary Camera 2 images. Two-dimensional spectroscopy undertaken with the Multipupil Fiber Spectrograph of the 6 m telescope of the Special Astrophysical Observatory of the Russian Acade…
The Luminosity Function of Early-Type Field Galaxies at z ~ 0.75
Ford, H. C.; Infante, L.; Zheng, W. +36 more
We measure the luminosity function of morphologically selected E/S0 galaxies from z=0.5 to 1.0 using deep high-resolution Advanced Camera for Surveys (ACS) imaging data. Our analysis covers an area of 48 arcmin2 (8 times the area of the Hubble Deep Field North) and extends 2 mag deeper (I~24 mag) than was possible in the Deep Groth Stri…
Hubble Space Telescope Observations of cD Galaxies and Their Globular Cluster Systems
Jordán, Andrés; Minniti, Dante; Marzke, Ronald O. +3 more
We have used WFPC2 on the Hubble Space Telescope (HST) to obtain F450W and F814W images of four cD galaxies (NGC 541 in Abell 194, NGC 2832 in Abell 779, NGC 4839 in Abell 1656, and NGC 7768 in Abell 2666) in the range 5400 km s-1<~cz<~8100 km s-1. For NGC 541, the HST data are supplemented by ground-based B and I image…
Menzel 3: a Multipolar Nebula in the Making
Guerrero, Martín A.; Chu, You-Hua; Miranda, Luis F.
The nebula Menzel 3 (Mz 3) has arguably the most complex bipolar morphology, consisting of three nested pairs of bipolar lobes and an equatorial ellipse. Its three pairs of bipolar lobes share the same axis of symmetry but have very different opening angles and morphologies: the innermost pair of bipolar lobes shows closed-lobe morphology, whereas…