Search Publications
The First Detections of the Extragalactic Background Light at 3000, 5500, and 8000 Å. I. Results
Madore, Barry F.; Freedman, Wendy L.; Bernstein, Rebecca A.
We present the first detection of the mean flux of the optical extragalactic background light (EBL) at 3000, 5500, and 8000 Å. Diffuse foreground flux at these wavelengths comes from terrestrial airglow, dust-scattered sunlight (zodiacal light), and dust-scattered Galactic starlight (diffuse Galactic light). We have avoided the brightest of these,…
The Mass of the Central Black Hole in the Seyfert Galaxy NGC 3783
Peterson, Bradley M.; Onken, Christopher A.
Improved analysis of ultraviolet and optical monitoring data on the Seyfert 1 galaxy NGC 3783 provides evidence for the existence of a supermassive, (8.7+/-1.1)×106Msolar, black hole in this galaxy. By using recalibrated spectra from the International Ultraviolet Explorer satellite and ground-based optical data, as well as re…
Hubble Space Telescope Imaging of the Circumnuclear Environments of the CfA Seyfert Galaxies: Nuclear Spirals and Fueling
Pogge, Richard W.; Martini, Paul
We present archival Hubble Space Telescope (HST) images of the nuclear regions of 43 of the 46 Seyfert galaxies found in the volume-limited, spectroscopically complete CfA Redshift Survey sample. Using an improved method of image contrast enhancement, we create detailed high-quality ``structure maps'' that allow us to study the distributions of du…
Optical and Ultraviolet Spectroscopy of SN 1995N: Evidence for Strong Circumstellar Interaction
Van Dyk, Schuyler D.; Filippenko, Alexei V.; Fransson, Claes +9 more
Optical and ultraviolet observations of the Type IIn supernova SN 1995N at epochs between 321 and 1799 days after the explosion show three distinct velocity components. The narrow lines come from circumstellar gas and show both low and high ionization. This component has a low filling factor and is photoionized by X-rays from the shock. The interm…
Empirical Densities, Kinetic Temperatures, and Outflow Velocities in the Equatorial Streamer Belt at Solar Minimum
Biesecker, D. A.; Strachan, L.; Kohl, J. L. +2 more
We use combined Ultraviolet Coronagraph Spectrometer and Large Angle Spectroscopic Coronagraph data to determine the O5+ outflow velocities as a function of height along the axis of an equatorial streamer at solar minimum and as a function of latitude (at 2.3 Rsolar from Sun center). The results show that outflow increases ra…
Narrow Components within the Fe Kα Profile of NGC 3516: Evidence of the Importance of General Relativistic Effects?
Nandra, K.; Turner, T. J.; Kraemer, S. B. +6 more
We present results from a simultaneous Chandra High Energy Transmission Grating and XMM-Newton observation of NGC 3516. We find evidence of several narrow components of Fe Kα along with a broad line. We consider the possibility that the lines arise in a blob of material ejected from the nucleus with velocity ~0.25c. We also consider an origin in a…
Cold Dust in Late-Type Virgo Cluster Galaxies
Madore, Barry F.; Tuffs, Richard J.; Popescu, Cristina C. +2 more
We have statistically analyzed the spatially integrated far-infrared (FIR) emissions of the complete volume- and luminosity-limited sample of late-type (later than S0) Virgo Cluster galaxies measured using the Infrared Space Observatory by Tuffs and coworkers in bands centered on 60, 100, and 170 µm. Thirty of 38 galaxies detected at all thr…
The Luminosity Dependence of Ultraviolet Absorption in Active Galactic Nuclei
Brandt, W. N.; Laor, Ari
We describe the results of a survey of the UV absorption properties of the Boroson & Green sample of active galactic nuclei (AGNs), which extends from the Seyfert (MV~=-21) to the luminous quasar (MV~=-27) level. The survey is based mostly on Hubble Space Telescope archival data available for >~1/2 of the 87 sample obj…
Steady Flows Detected in Extreme-Ultraviolet Loops
Golub, Leon; Winebarger, Amy R.; Warren, Harry +2 more
Recent Transition Region and Coronal Explorer (TRACE) observations have detected a class of active region loops whose physical properties are inconsistent with previous hydrostatic loop models. In this Letter we present the first co-aligned TRACE and the Solar Ultraviolet Measurement of Emitted Radiation (SUMER) observations of these loops. Althou…
Correlation of the Coronal Mass Ejection Productivity of Solar Active Regions with Measures of Their Global Nonpotentiality from Vector Magnetograms: Baseline Results
Falconer, D. A.; Moore, R. L.; Gary, G. A.
From conventional magnetograms and chromospheric and coronal images, it is known qualitatively that the fastest coronal mass ejections (CMEs) are magnetic explosions from sunspot active regions in which the magnetic field is globally strongly sheared and twisted from its minimum-energy potential configuration. In this paper, we present measurement…