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Multiwavelength Monitoring of the Dwarf Seyfert 1 Galaxy NGC 4395. II. X-Ray and Ultraviolet Continuum Variability
O'Neill, Paul M.; Kaspi, Shai; Laor, Ari +7 more
We report on two Chandra observations, and a simultaneous Hubble Space Telescope ultraviolet observation, of the dwarf Seyfert 1 galaxy NGC 4395. Each Chandra observation had a duration of ~30 ks, with a separation of ~50 ks. The spectrum was observed to harden between these observations via a scaling down of the soft-band flux. The interobservati…
The Warped Nuclear Disk of Radio Galaxy 3C 449
Baum, Stefi A.; O'Dea, Christopher P.; Sparks, William B. +11 more
Among radio galaxies containing nuclear dust disks, the bipolar jet axis is generally observed to be perpendicular to the disk major axis. The FR I radio source 3C 449 is an outlier to this statistical majority, as it possesses a nearly parallel jet/disk orientation on the sky. We examine the 600 pc dusty disk in this galaxy with images from the H…
X-Ray Number Counts of Normal Galaxies
Zezas, A.; Georgakakis, A.; Georgantopoulos, I. +2 more
We use the number counts of X-ray-selected normal galaxies to explore their evolution by combining the most recent wide-angle shallow and pencil-beam deep samples available. The differential X-ray number counts, dN/dS, for early- and late-type normal galaxies are constructed separately and then compared with the predictions of the local X-ray lumi…
Carrington Maps of the Upper Photosphere
Warren, H. P.; Sheeley, N. R., Jr.
We have used images of the Sun's disk, obtained in the 6767 Å continuum with the Michelson Doppler Interferometer (MDI) on the Solar and Heliospheric Observatory (SOHO), to make Carrington maps of the upper photosphere during the years 1996-2005. Each map is constructed from observations near the limb where the continuum radiation originates relat…
Magnetic Structures of Solar Active Regions, Full-Halo Coronal Mass Ejections, and Geomagnetic Storms
Liu, Y.; Webb, D. F.; Zhao, X. P.
We have analyzed three active regions to investigate the relationship between magnetic configurations of active regions and geomagnetic storms. Each active region was associated with multiple full-halo coronal mass ejections (CMEs). This study demonstrates that, although full-halo CMEs may originate from the same active region, it is not necessary…
The Tully-Fisher Relation in Cluster Cl 0024+1654 at z=0.4
Koo, David C.; Simard, Luc; Phillips, Andrew C. +1 more
Using moderate-resolution Keck spectra, we have examined the velocity profiles of 15 members of cluster Cl 0024+1654 at z=0.4. WFPC2 images of the cluster members have been used to determine structural parameters, including disk sizes, orientations, and inclinations. We compare two methods of optical rotation curve analysis for kinematic measureme…
A Study of H2 Emission in the Bipolar Proto-Planetary Nebula IRAS 17150-3224
Kwok, Sun; Hrivnak, Bruce J.; Su, Kate Y. L. +2 more
H2 emission has been detected in the bipolar proto-planetary nebula IRAS 17150-3224 from the 1-0 S(1), 1-0 S(0), and 2-1 S(1) transitions in the 2 µm region. Line ratios suggest that this emission is due to collisional excitation. High-resolution imaging with NICMOS on HST shows that the emission comes from four regions: clumps ne…
On the Nature of the Ultraluminous X-Ray Transient in Cen A (NGC 5128)
Wu, Kinwah; Tennant, Allyn F.; Swartz, Douglas A. +2 more
We combine nine ROSAT, nine Chandra, and two XMM-Newton observations of the Cen A galaxy to obtain the X-ray light curve of 1RXH J132519.8-430312 (=CXOU J132519.9-430317) spanning 1990-2003. The source reached a peak 0.1-2.4 keV flux FX>10-12 ergs cm-2 s-1 during a 10 day span in 1995 July. The inferr…
Iron Depletion in the Hot Bubbles in Planetary Nebulae
Zhekov, Svetozar A.; Richer, Michael G.; Arrieta, Anabel +1 more
We have searched for the emission from [Fe X] λ6374 and [Fe XIV] λ5303 that is expected from the gas emitting in diffuse X-rays in BD +30°3639, NGC 6543, NGC 7009, and NGC 7027. Neither line was detected in any object. Models that fit the X-ray spectra of these objects indicate that the [Fe X] λ6374 emission should be below our detection threshold…
A Cluster of Galaxies Hiding behind M31: XMM-Newton Observations of RX J0046.4+4204
Trudolyubov, Sergey; Kotov, Oleg; Vestrand, W. Thomas
We report on our serendipitous discovery with the XMM-Newton Observatory of a luminous X-ray-emitting cluster of galaxies that is located behind the Andromeda galaxy (M31). X-ray emission from the cluster was detected previously by ROSAT and cataloged as RX J0046.4+4204, but it was not recognized as a galaxy cluster. The much greater sensitivity o…