September 15, 1999
We present and analyse HST/WFPC2 broad- and narrow-band observations of the central regions of 19 nearby radio-loud early-type galaxies. Together with two more galaxies they form a complete sample of Fanaroff & Riley Type I galaxies. We obtained V- and I-band images and narrow-band images centered on the \HalphaNII emission lines. We use archival data for six galaxies. We describe the data reduction, give isophotal fits and analyse the central emission-line gas and dust distributions. Our main conclusions are the following. Although obscuration by dust inhibits a direct determination of central cusp slopes, the data suggest most but not all galaxies have shallow cores. Dust is detected in all but two galaxies. There is a wide variety of central dust morphologies, ranging from central disks to lanes and irregular distributions. The analysis suggests the difference between disks and lanes is intrinsic and not due to different viewing angles. Central emission-line gas is detected in all galaxies. Extended low-surface-brightness emission is always associated with the dust features. In a subsequent paper we will present a detailed analysis of the relation between these central properties and the nuclear activity.
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December 6, 2000
We have observed a complete sample of 21 nearby (D < 70h^{-1} Mpc) Fanaroff & Riley Type I galaxies with HST/WFPC2 and detected dust disks and lanes in 19 of them. The radio jets are roughly perpendicular to the dust which is used to constrain the Doppler boosting factors of the radio jet and cores. The VLBA core flux correlates with the central Halpha+[NII] flux which might indicate that the VLBA core is dominated by an isotropic component. Twelve galaxies show nuclear optic...
February 15, 2001
We present high resolution R-band images of the central regions of 67 early-type galaxies obtained with the Wide Field and Planetary Camera 2 (WFPC2) aboard the Hubble Space Telescope (HST). Our sample strikingly confirms the complex morphologies of the central regions of early-type galaxies. In particular, we detect dust in 43 percent of all galaxies, and evidence for embedded stellar disks in a remarkably large fraction of 51 percent. In 14 of those galaxies the disk-like s...
February 16, 2001
We examine the dust properties of a nearby distance-limited sample of early type galaxies using the WFPC2 of the Hubble Space Telescope. Dust is detected in 29 out of 67 galaxies (43%), including 12 with small nuclear dusty disks. In a separate sample of 40 galaxies biased for the detection of dust by virtue of their detection in the IRAS 100 micron band, dust is found in ~78% of the galaxies, 15 of which contain dusty disks. In those galaxies with detectable dust, the appare...
June 21, 2001
We present initial results of our analysis of line emission produced in gas disks found at the centers of a sample of nearby, radio galaxies with radio jets. We obtained data using STIS (The Space Telescope Imaging Spectrograph) at three parallel slit positions on the nucleus of each galaxy. This allows us to map the H$\alpha$ + [NII] flux, the gas radial velocity and the velocity dispersion. We find evidence of rotating disks in 11 of the sample galaxies and we can not curre...
February 22, 2014
We present results of optical broad-band and narrow-band Halpha observations of a sample of forty nearby early-type galaxies. The majority of sample galaxies are known to have dust in various forms viz. dust lanes, nuclear dust and patchy/filamentary dust. A detailed study of dust was performed for 12 galaxies with prominent dust features. The extinction curves for these galaxies run parallel to the Galactic extinction curve, implying that the properties of dust in these gala...
November 5, 2004
We present $V$ and $I$ continuum images and H$\alpha$+[N II] maps of nine early-type galaxies observed with the Wide Field Channel of the Advanced Camera for Surveys on the Hubble Space Telescope. Dust and ionized gas are detected in all galaxies. The optical nebulae are primarily concentrated on the nuclei and extend out to radii of a few hundred parsecs, in compact clumps, filaments, or disks. Two galaxies, NGC 6166 and NGC 6338, also possess diffuse, ionized filaments on k...
June 2, 2003
We present the results of the analysis of a set of medium resolution spectra, obtained by the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope, of the emission line gas present in the nuclei of a complete sample of 21 nearby, early-type galaxies with radio jets (the UGC FR-I Sample). For each galaxy nucleus we present spectroscopic data in the region of H-alpha and the dervived kinematics. We find that in 67% of the nuclei the gas appears to be rotat...
December 1, 2004
We analyze HST+WFPC2 images of 77 early-type galaxies. Brightness profiles are classed into "core" or "power-law" forms. Cores are typically rounder than power-law galaxies. Nearly all power-laws with central ellipticity >=0.3 have stellar disks, implying that disks are present in power-laws with epsilon <0.3, but are not visible due to unfavorable geometry. A few low-luminosity core galaxies also have disks; these may be transition forms from power-laws. Cores and power-laws...
February 28, 2001
We present preliminary results from surface photometry of a sample of early-type galaxies observed with NICMOS on board HST in the F160W (H-band) filter. Dust is found to occur mostly in galaxies which possess unresolved nuclei, and in a few cases the presence of dust causes the isophotes to appear boxy. We performed a 2-D modeling of the host galaxy light distribution using the empirical Nuker function, which proves to be an adequate representation of the surface-brightness ...
May 22, 2001
We present surface photometry for the central regions of a sample of 33 early-type (E, S0, and S0/a) galaxies observed at 1.6 microns (H band) using the Hubble Space Telescope (HST). We employ a new technique of two-dimensional fitting to extract quantitative parameters for the bulge light distribution and nuclear point sources, taking into consideration the effects of the point-spread function. Parameterizing the bulge profile with a ``Nuker'' law, we confirm that the centra...