Search Publications
Spectral Evolution of the Luminous Blue Variable NGC 2363-V1. I. Observations and Qualitative Analysis of the Ongoing Giant Eruption
Drissen, Laurent; Crowther, Paul A.; Petit, Véronique
We describe the spectroscopic evolution of the extragalactic luminous blue variable NGC 2363-V1 from 1997 to 2004. Photometrically, this star has gradually faded by 0.3 mag in the V band over this period, while spectra obtained with the Hubble Space Telescope show dramatic changes: a gradual strengthening of the UV flux (a fourfold increase at 120…
Remarkable Disk and Off-Nuclear Starburst Activity in the Tadpole Galaxy as revealed by the Spitzer Space Telescope
Berta, S.; Rodighiero, G.; Hatziminaoglou, E. +20 more
We present ground-based optical and Spitzer Space Telescope infrared imaging observations of the interacting galaxy UGC 10214, the Tadpole galaxy (z=0.0310), focusing on the star formation activity in the nuclear, disk, spiral arms, and tidal tail regions. The ground-based optical data set spans a wavelength range between 0.3 and 0.8 µm, the…
A Snapshot Survey for Gravitational Lenses among z>=4.0 Quasars. II. Constraints on the 4.0<z<5.4 Quasar Population
Strauss, Michael A.; Brinkmann, J.; Fan, Xiaohui +7 more
We report on i-band snapshot observations of 157 Sloan Digital Sky Survey quasars at 4.0<z<5.4 using the Advanced Camera for Surveys on the Hubble Space Telescope (HST) to search for evidence of gravitational lensing of these sources. None of the quasars appear to be strongly lensed and multiply imaged at the angular resolution (~0.1") and s…
Understanding the Nuclear Gas Dispersion in Early-Type Galaxies in the Context of Black Hole Demographics
van der Marel, Roeland P.; Verdoes Kleijn, Gijs A.; Noel-Storr, Jacob
The majority of nearby early-type galaxies contain detectable amounts of emission-line gas at their centers. The nuclear gas kinematics form a valuable diagnostic of the central black hole (BH) mass. Here we analyze and model Hubble Space Telescope STIS observations of a sample of 27 galaxies; 16 Fanaroff-Riley Type I radio galaxies and 11 (more) …
Adaptive Optics Imaging of Low-Redshift Damped Lyα Quasar Absorbers
Kulkarni, Varsha P.; Chun, Mark R.; Gharanfoli, Soheila +1 more
We have carried out a high angular resolution near-infrared imaging study of the fields of six quasars with seven strong absorption-line systems at z<0.5, using the Hokupa'a adaptive optics system and the Quick Infrared Camera on the Gemini North telescope. These absorption systems include four classical damped Lyα absorbers (DLAs), two sub-DLA…
The Inner Resonance Ring of NGC 3081. II. Star Formation, Bar Strength, Disk Surface Mass Density, and Mass-to-Light Ratio
Byrd, Gene G.; Freeman, Tarsh; Buta, Ronald J.
We complement our Hubble Space Telescope (HST) observations of the inner ring of the galaxy NGC 3081 using an analytical approach and n-body simulations. We find that a gas cloud inner (r) ring forms under a rotating bar perturbation with very strong azimuthal cloud crowding where the ring crosses the bar major axis. Thus, star formation results n…
A ROSAT Survey of Contact Binary Stars
McKay, T. A.; Geske, M. T.; Gettel, S. J.
Contact binary stars are common variable stars that are all believed to emit relatively large fluxes of X-rays. In this work we combine a large new sample of contact binary stars derived from the ROTSE-I telescope with X-ray data from the ROSAT All Sky Survey (RASS) to estimate the X-ray volume emissivity of contact binary stars in the Galaxy. We …
Star-forming Galaxies at Intermediate Redshifts: Morphology, Ages, and Sizes
Casertano, S.; Dahlen, T.; de Mello, D. F. +2 more
We present an analysis of the deepest near-UV image obtained with the Hubble Space Telescope using the WFPC2 (F300W) as part of the parallel observations of the Hubble Ultra Deep Field campaign. The U-band 10 σ limiting magnitude measured over 0.2 arcsec2 is mAB=27.5, which is 0.5 mag deeper than that in the Hubble Deep Field…
Examining the Seyfert-Starburst Connection with Arcsecond-Resolution Radio Continuum Observations
Ryder, Stuart D.; Laine, Seppo; Beck, Rainer +2 more
We compare the arcsecond-scale circumnuclear radio continuum properties of five Seyfert and five starburst galaxies, concentrating on the search for any structures that could imply a spatial or causal connection between the nuclear activity and a circumnuclear starburst ring. No evidence is found in the radio emission for a link between the trigge…
Chandra Observation of NGC 6822
Tennant, Allyn F.
Chandra observed the nearby dwarf galaxy NGC 6822. There are 70 sources in the Chandra field, two of which are fairly extended and likely background clusters of galaxies. A third source was resolved by Chandra that has the same size and position as a known supernova remnant. The suspected variability detected from this source in previous missions …