Search Publications
New Insights into the Physical Nature of LINERs from a Multiwavelength Analysis of the Nucleus of M81
Filippenko, Alexei V.; Ho, Luis C.; Sargent, Wallace L. W.
We discuss the physical conditions and excitation of the nucleus of M81 by combining ground-based optical spectra, archival Hubble Space Telescope (HST) Ultraviolet (UV) and optical spectral, and published X- ray measurements. This well known low-ionization nuclear emission-line region (LINER) is representative of a general class of objects though…
The Centers of Early-Type Galaxies With HST. II. Empirical Models and Structural Parameters
Faber, S. M.; Dressler, A.; Byun, Y. -I. +6 more
We present a set of structural parameters for the central parts of 57 early-type galaxies observed with the Planetary Camera of the Hubble Space Telescope. These parameters are based on a new empirical law that successfully characterizes the centers of early-type galaxies. This empirical law assumes that the surface brightness profile is a combina…
A Comparison between the Narrow-Line Regions of Seyfert 1 and Seyfert 2 Galaxies
Kinney, Anne L.; Schmitt, Henrique R.
We present high-resolution narrow-band [O III] images of Seyfert 1 and Seyfert 2 galaxies, obtained in the Hubble Space Telescope Data Archive. The continuum-subtracted [O III] images were used to measure the narrow- line region (NLR) sizes and compare them with the predictions from the Unified Scheme. This paper shows that the Seyfert 1 NLR sizes…
Hubble Space Telescope Spectroscopic Evidence for a 2 10 9 Msun Black Hole in NGC 3115
Gebhardt, Karl; Richstone, Douglas; Kormendy, John +7 more
The discovery by Kormendy & Richstone of an M• ~= 109 M⊙ massive dark object (MDO) in NGC 3115 is confirmed with higher resolution spectroscopy from the Canada-France-Hawaii Telescope (CFHT) and the Hubble Space Telescope (HST). Measurements with the CFHT and Subarcsecond Imaging Spectrograph improve the resolution from sigma * = 0."44 to sigm…
Simultaneous Multiwavelength Spectrum and Variability of 3C 279 from 10 9 to 10 24 Hz
Dermer, C. D.; Tornikoski, M.; Hermsen, W. +25 more
Data from a number of monitoring programs have been combined with data from the Compton Gamma Ray Observatory and the Ginga X-ray satellite to construct a spectrum covering nearly 15 decades in frequency during or near the time of the 3C 279 γ-ray flare observed by EGRET in 1991 June. A much less complete spectrum is presented for 1991 October. Li…
Calibration and performance of the ISO Long-Wavelength Spectrometer.
Omont, A.; Ade, P. A. R.; Liseau, R. +52 more
The wavelength and flux calibration, and the in-orbit performance of the Infrared Space Observatory Long-Wavelength Spectrometer (LWS) are described. The LWS calibration is mostly complete and the instrument's performance in orbit is largely as expected before launch. The effects of ionising radiation on the detectors, and the techniques used to m…
Spectral analysis of hot helium-rich white dwarfs.
Werner, K.; Dreizler, S.
We present a model atmosphere analysis of most known hot helium-rich white dwarfs of spectral type DO. The stars represent the non-DA white dwarf cooling sequence from the hot end (T_eff_=~120000K) down to the DB gap (T_eff_=~45000K). From medium resolution optical spectra, effective temperatures, surface gravities, and element abundances are dete…
Hubble Space Telescope Ultraviolet Images of Five Circumnuclear Star-Forming Rings
Filippenko, A. V.; Macchetto, F. D.; Ho, L. C. +5 more
We present UV (~2300 A) images, obtained with the Hubble Space Telescope (HST) Faint Object Camera, of the central 20" of five galaxies containing circumnuclear star-forming rings. The five galaxies are from a well- defined sample of 103 normal, nearby galaxies we have observed with HST. At the HST resolution (0.05"), the rings break up into discr…
Hubble Space Telescope Observations of M32: The Color-Magnitude Diagram
Holtzman, J. A.; Faber, S. M.; Stetson, P. B. +9 more
We present a V-I color-magnitude diagram for a region 1' - 2' from the center of M32 based on Hubble Space Telescope WFPC2 images. The broad color-luminosity distribution of red giants shows that the stellar population comprises stars with a wide range in metallicity. This distribution cannot be explained by a spread in age. The blue side of the g…
The Jet of M87 at Tenth-Arcsecond Resolution: Optical, Ultraviolet, and Radio Observations
Sparks, W. B.; Macchetto, F.; Biretta, J. A.
The European Space Agency's Faint Object Camera (FOC) on the Hubble Space Telescope (HST) was used to obtain optical and UV imaging of the jet of M87 prior to the HST refurbishment. We present a detailed comparison to new VLA radio observations at similar spatial resolution and flux information for the radio, optical, and UV bands. While the radio…