Search Publications
New HST Observations of the Halo Gas of NGC 3067: Limits on the Extragalactic Ionizing Background at Low Redshift and the Lyman Continuum Escape Fraction
Shull, J. Michael; Stocke, John T.; Tumlinson, Jason +1 more
We present ultraviolet spectroscopy from HST/GHRS and reanalyze existing Hα images of the quasar/galaxy pair 3C 232/NGC 3067 and of the halo gas associated with NGC 3067. The spectra permit measurement of, or limits on, the column densities of Fe I, Fe II, Mg I, and Mg II in the absorbing cloud. Two distinct models of the extragalactic radiation f…
Stellar Kinematics of the Double Nucleus of M31
King, Ivan R.; Statler, Thomas S.; Crane, Philippe +1 more
We report observations of the double nucleus of M31 with the f/48 long-slit spectrograph of the Hubble Space Telescope Faint Object Camera. We obtain a total exposure of 19,000 s over seven orbits, with the 0.063"-wide slit along the line between the two brightness peaks (P.A. 42 deg). Careful correction of the raw data for detector backgrounds an…
Mapping the Variegated Surface of Pluto
Buie, Marc W.; Tholen, David J.; Young, Eliot F. +2 more
During the period from 1985 through 1990, Pluto and its satellite Charon underwent a series of transits, eclipses, and occultations, which are collectively called ``mutual events.'' The albedo distribution of Pluto's sub-Charon hemisphere can be determined from these events with a spatial resolution that surpasses any current direct-imaging scheme…
Determining the Galactic Mass Distribution Using Tidal Streams from Globular Clusters
Murali, Chigurupati; Dubinski, John
We discuss how to use tidal streams from globular clusters to measure the mass distribution of the Milky Way. Recent proper-motion determinations for globular clusters from plate measurements and Hipparcos astrometry provide several good candidates for Galactic mass determinations in the intermediate halo far above the Galactic disk, including Pal…
Young Stellar Nuclei in the Lenticular Galaxies. I. NGC 1023 and NGC 7332
Sil'chenko, O. K.
As a result of bidimensional spectroscopy of the central parts of two nearby lenticular galaxies, NGC 1023 and NGC 7332, undertaken with the Multi-Pupil Field Spectrograph of the 6 m telescope of the Special Astrophysical Observatory, their chemically decoupled stellar nuclei are found to be substantially younger than the surrounding bulges: the m…
A Hubble Space Telescope Optical and Ground-based Near-Infrared Study of the Giant Nuclear Ring in ESO 565-11
Buta, R.; Crocker, D. A.; Byrd, G. G.
We present multiband Wide Field Planetary Camera 2 images of the central regions of ESO 565-11, a peculiar southern barred galaxy recently shown to have the largest known example of a circumnuclear starburst ring. We also present ground-based near-infrared H-band imaging and photometry of the galaxy. The results provide an interesting picture of t…
Radio Detections of Stellar Winds from the Pistol Star and Other Stars in the Galactic Center Quintuplet Cluster
Goss, W. M.; Morris, Mark; Lang, Cornelia C. +1 more
Very Large Array images of the Sickle and Pistol H II regions near the Galactic center at 8.3 and 4.9 GHz reveal six point sources in the region where the dense Quintuplet stellar cluster is located. The spectral indices of five of these sources between 6 and 3.6 cm have values of α=0.5 to 0.8 (where Sν~να), consistent with t…
The Complex Protostellar Source IRAS 04325+2402
Hartmann, Lee; Calvet, Nuria; Jayawardhana, Ray +2 more
We report Hubble Space Telescope near-infrared NICMOS observations of a remarkable low-luminosity Class I (protostellar) source in the Taurus Molecular Cloud. IRAS 04325+2402 exhibits a complex bipolar scattered light nebula. The central continuum source is resolved and may be multiple, or it may be crossed by a small dust lane. Complex arcs seen …
Polarized Narrow-Line Emission from the Nucleus of NGC 4258
Filippenko, Alexei V.; Ho, Luis C.; Barth, Aaron J. +5 more
The detection of polarized continuum and line emission from the nucleus of NGC 4258 by Wilkes et al. in 1995 provides an intriguing application of the unified model of Seyfert nuclei to a galaxy in which there is known to be an edge-on, rotating disk of molecular gas surrounding the nucleus. Unlike most Seyfert nuclei, however, NGC 4258 has strong…
Deep Near-Infrared Images and ISOCAM Observations of Chamaeleon I North
Olofsson, G.; Roth, M.; Nordh, L. +3 more
We present the results of deep near-infrared imaging and ISOCAM observations of three selected regions localized in the northern part of the Chamaeleon I dark cloud, in order to search for the low-luminosity population. In an area of 3x3 arcmin^2 centered on the bipolar molecular outflow, which is the densest part of the cloud, we have discovered …