Search Publications
High-Resolution Millimeter and Infrared Observations of the Hot Spots of Cygnus A
Miley, G. K.; Carilli, C. L.; Kurk, J. D. +2 more
We present high-resolution, polarimetric imaging of the radio hot spots of Cygnus A at 7 mm with the Very Large Array and derive limits to hot spot emission at 12 µm with the Infrared Space Observatory (ISO). The 7 mm images reveal the hot spot structure in total and polarized intensity in unprecedented detail, including images of the projec…
The Morphologically Divided Redshift Distribution of Faint Galaxies
Green, Richard F.; Im, Myungshin; Roche, Nathan +4 more
We have constructed a morphologically divided redshift distribution of faint field galaxies using a statistically unbiased sample of 196 galaxies brighter than I=21.5 for which detailed morphological information (from the Hubble Space Telescope) as well as ground-based spectroscopic redshifts are available. Galaxies are classified into three rough…
The Cepheid distance to M96 and the Hubble constant
Ferguson, H. C.; Tanvir, N. R.; Shanks, T.
HST WFPC2 observations of Cepheids in M96 (NGC 3368) are used to find a distance to that galaxy of 11.2+/-1.0Mpc. This estimate is based on a calibration of the Cepheid period-luminosity relation in the Large Magellanic Cloud, and includes a correction for the difference in metallicity between the two systems. There are good reasons for believing …
NICMOS Imaging of Molecular Hydrogen Emission in Seyfert Galaxies
Rieke, G. H.; Alonso-Herrero, A.; Quillen, A. C. +3 more
We present near-infrared (NICMOS) imaging of broadband and molecular hydrogen emission in Seyfert galaxies. In six of 10 Seyfert galaxies we detect resolved or extended emission in the 1-0 S(1) 2.121 µm or 1-0 S(3) 1.9570 µm molecular hydrogen lines. We did not detect emission in the most distant galaxy or in two Seyfert 1 galaxies bec…
The Excitation Mechanism of Emission-Line Regions in Seyfert Galaxies
Tsvetanov, Zlatan; Koratkar, Anuradha; Dopita, Michael +2 more
We present Hubble Space Telescope UV/optical spectrophotometry and ground-based optical spectrophotometry of the brightest knots in the emission-line regions of the Seyfert galaxies NGC 5643 and NGC 5728. These objects have ionization cones, radio and soft X-ray emission, and evidence of nuclear outflows and winds, suggesting that shocks may be as…
[CII] emission and star formation in late-type galaxies
Tuffs, R. J.; Pierini, D.; Leech, K. J. +1 more
We demonstrate the existence of a reasonably tight linear correlation between the ratio of the [CII (^2P_3/2-^2 P_1/2)] (lambda 158 mu m) fine-structure cooling line intensity to the [^12CO (J=1 -> 0)] (lambda 2.6 mm) line emission, I_CII/I_CO, and the H alpha (lambda 6563 A ) equivalent width (EW), over the range 2-71 A in H alpha EW, for a sa…
The effects of opacity in the transition region of YZ CMi
Mathioudakis, M.; Keenan, F. P.; Phillips, K. J. H. +2 more
It has generally been assumed that the emission from the upper atmosphere of late-type stars is optically thin. In the present paper we use the Si IV and C IV resonance lines to investigate this assumption for the active dMe star YZ CMi. The significant deviations of the line ratios from their optically thin values, demonstrate that opacity can be…
Phase Differences and Gains between Intensity and Velocity in Low-Degree Acoustic Modes Measured by SOHO
Jiménez, Antonio; Severino, Giuseppe; Roca Cortés, Teodoro +1 more
Helioseismic instruments aboard SOHO are making possible a more accurate way of investigating the internal structure of the Sun. Making use of the different techniques and characteristics of these instruments, it is possible to measure solar oscillations as variations of the photospheric velocity (GOLF, MDI) or as irradiance and radiance fluctuati…
Interpreting the Solar Limb Shape Distortions
Armstrong, James; Kuhn, J. R.
Accurate measurements of the solar oblateness have recently been obtained from the SOHO/MDI satellite experiment. The new data are sufficiently accurate to measure nonnegligible multipole shape terms of higher order than the oblateness. Here we extend earlier solar limb shape calculations and compare the new data with the helioseismic evidence for…
Hubble Space Telescope WFPC2 Imaging of SN 1979C and Its Environment
Filippenko, Alexei V.; Fransson, Claes; Chevalier, Roger A. +6 more
The locations of supernovae in the local stellar and gaseous environment in galaxies contain important clues to their progenitor stars. As part of a program to study the environments of supernovae using Hubble Space Telescope imaging data, we have examined the environment of the Type II-L supernova SN 1979C in NGC 4321 (M100). We place rigorous co…