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Chandra Observations of the X-Ray Narrow-Line Region in NGC 4151
Marshall, H. L.; Lee, J. C.; Ogle, P. M. +1 more
We present the first high-resolution X-ray spectrum of the Seyfert 1.5 galaxy NGC 4151. Observations with the Chandra High-Energy Transmission Grating Spectrometer reveal a spectrum dominated by narrow emission lines from a spatially resolved (1.6 kpc), highly ionized nebula. The X-ray narrow-line region is composite, consisting of both photoioniz…
The Photospheric Convection Spectrum
Raymond, J.; Hathaway, D. H.; Bogart, R. S. +5 more
Spectra of the cellular photospheric flows are determined from observations acquired by the MDI instrument on the SOHO spacecraft. Spherical harmonic spectra are obtained from the full-disk observations. Fourier spectra are obtained from the high-resolution observations. The p-mode oscillation signal and instrumental artifacts are reduced by tempo…
How Much Do Helioseismological Inferences Depend on the Assumed Reference Model?
Basu, Sarbani; Pinsonneault, M. H.; Bahcall, John N.
We investigate systematic uncertainties in determining the profiles of the solar sound speed, density, and adiabatic index using helioseismological techniques. We find that rms uncertainties (averaged over the Sun) of ~0.02%-0.04% are contributed to the sound-speed profile by each of three sources: (1) the choice of assumed reference model, (2) th…
The Hubble Deep Fields
Dickinson, Mark; Ferguson, Henry C.; Williams, Robert
The Hubble space telescope observations of the northern Hubble deep field, and more recently its counterpart in the south, provide detections and photometry for stars and field galaxies to the faintest levels currently achievable, reaching magnitudes V ~ 30. Since 1995, the northern Hubble deep field has been the focus of deep surveys at nearly al…
Low- and High-Ionization Absorption Properties of Mg II Absorption-selected Galaxies at Intermediate Redshifts. I. General Properties
Charlton, Jane C.; Schneider, Donald P.; Steidel, Charles C. +4 more
We present extensive metal-line absorption properties for 45 absorption systems that were selected by their Mg II absorption at redshifts between 0.4 and 1.4. For each system the properties of several chemical species are determined, including a wide range of ionization conditions. In the optical, the absorption systems have been observed at ~6 km…
A Candidate Substellar Companion to HR 7329
Weinberger, Alycia J.; Schneider, Glenn; Hines, Dean C. +10 more
We present the discovery of a candidate substellar companion from a survey of nearby young stars made with the Near-Infrared Camera and Multiobject Spectrometer coronagraph on the Hubble Space Telescope. The H~12 mag object was discovered approximately 4" from the young A0 V star HR 7329. Using follow-up spectroscopy from the Space Telescope Imagi…
An Excess of Submillimeter Sources near 4C 41.17: A Candidate Protocluster at Z = 3.8?
Ivison, R. J.; Smail, Ian; Dunlop, J. S. +3 more
Biased galaxy-formation theories predict that massive galaxies at high redshifts should act as signposts to high-density environments in the early universe, which subsequently evolve into the cores of the richest clusters seen at the present day. These regions are characterized by overdensities of young galaxies, perhaps including a population of …
STIS Coronagraphic Imaging of the Herbig AE Star: HD 163296
Kimble, R.; Linsky, J. L.; Bruhweiler, F. C. +7 more
Coronagraphic imaging with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope reveals a ~450 AU radius circumstellar disk around the Herbig Ae star HD 163296. A broadband (0.2-1.0 µm) reflected light image shows the disk oriented at a position angle of 140deg+/-5deg and inclined to our line of …
The Dust-Radio Connection in 3CR Radio Galaxies
Baum, Stefi A.; Miley, George; Sparks, William +6 more
We investigate dust in the nuclear regions of radio galaxies on the basis of 120 images of 3CR radio galaxies in the redshift range 0<z<0.5, taken with the WFPC-2 on the Hubble Space Telescope. At least 40 of these radio galaxies show evidence for absorption due to clumpy dust features; a large range of morphologies is observed for these dus…
The Mid-Infrared Spectra of Normal Galaxies
Helou, G.; Malhotra, S.; Werner, M. W. +2 more
The mid-infrared spectra (2.5-5 and 5.7-11.6 µm) obtained by ISOPHOT reveal the interstellar medium emission from galaxies powered by star formation to be strongly dominated by the aromatic features at 6.2, 7.7, 8.6, and 11.3 µm. Additional emission appears in between the features, and an underlying continuum is clearly evident at 3-5 …