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A Star Catalog for the Open Cluster NGC 188
Stetson, Peter B.; VandenBerg, Don A.; McClure, Robert D.
We present new BVRI broadband photometry for the old open cluster NGC 188, based on an analysis of 299 CCD images either obtained by us, donated by colleagues, or retrieved from public archives. We compare our results on a star-by-star basis with data from 11 previous photometric data sets for the cluster. We homogenize and merge the data from all…
The X-ray variability of the narrow-line type 1 Seyfert galaxy IRAS 13224-3809 from an XMM-Newton observation
Brandt, W. N.; Fabian, A. C.; Boller, Th. +5 more
We report on the XMM-Newton timing properties of the most X-ray variable, radio-quiet, narrow-line type 1 Seyfert galaxy IRAS 13224-3809. IRAS 13224-3809 continues to display the extremely variable behaviour that was previously observed with ROSAT and ASCA; however, no giant, rapid flaring events are observed. We detect variations by a factor as h…
The Highly Relativistic Kiloparsec-Scale Jet of the Gamma-Ray Quasar 0827+243
Jorstad, Svetlana G.; Marscher, Alan P.
We present Chandra X-ray (0.2-8 keV) and Very Large Array radio (15 and 5 GHz) images of the γ-ray-bright, superluminal quasar 0827+243. The X-ray jet bends sharply-by ~90°, presumably amplified by projection effects-5" from the core. Only extremely weak radio emission is detected between the nuclear region and the bend. The X-ray continuum spectr…
Circumnuclear Structure and Black Hole Fueling: Hubble Space Telescope NICMOS Imaging of 250 Active and Normal Galaxies
Malkan, M. A.; Hunt, L. K.
Why are the nuclei of some galaxies more active than others? If most galaxies harbor a central massive black hole, the main difference is probably in how well it is fueled by its surroundings. We investigate the hypothesis that such a difference can be seen in the detailed circumnuclear morphologies of galaxies using several quantitatively defined…
Case studies of the dynamics of ionospheric ions in the Earth's magnetotail
Lundin, R.; Sauvaud, J. -A.; Balogh, A. +19 more
This paper presents case studies of the dynamics of the terrestrial ions in the midplasma sheet and inside the lobes (∼17-19 RE). The high time resolution measurements of H+, He+, and O+ ions made on board Cluster show that these ions are massively injected into the tail during substorms/storms from the …
M31's Undisturbed Thin Disk of Globular Clusters
Harding, Paul; Morrison, Heather L.; Perrett, Kathy +1 more
We show that there is a subsystem of the M31 globular clusters with thin-disk kinematics. These clusters span the entire metallicity range of the M31 globular cluster system, in contrast to the (thick) disk globular clusters in the Milky Way, which are predominantly metal-rich. Disk globular clusters are found across the entire disk of M31 and for…
Fragmentation Hierarchy of Bright Sungrazing Comets and the Birth and Orbital Evolution of the Kreutz System. I. Two-Superfragment Model
Sekanina, Zdenek; Chodas, Paul W.
A back-and-forth orbit integration technique, developed for our previous investigation of the splitting of the parent of the sungrazers C/1882 R1 and C/1965 S1, is now applied in an effort to understand the history and orbital evolution of the Kreutz sungrazer system, starting with the birth of two subgroups, which show prominently among the brigh…
Transient Relativistically Shifted Lines as a Probe of Black Hole Systems
Turner, T. J.; Kraemer, S. B.; Reeves, J. N.
X-ray spectra of Seyfert galaxies have revealed a new type of X-ray spectral feature, one that appears to offer important new insight into the black hole system. XMM revealed several narrow emission lines redward of Fe Kα in NGC 3516. Since that discovery the phenomenon has been observed in other Seyfert galaxies, e.g., NGC 7314 and ESO 198-G24. W…
The X-Ray Jet of 3C 120: Evidence for a Nonstandard Synchrotron Spectrum
Harris, D. E.; Walker, R. C.; Mossman, A. E.
We report on archival data from the Chandra X-Ray Observatory for the radio jet of 3C 120. We consider the emission process responsible for the X-rays from four knots using spectra constructed from radio, optical, and X-ray intensities. While a simple synchrotron model is adequate for three of the knots, the fourth (``k25''), which was previously …
Jet emission in NGC 1052 at radio, optical, and X-ray frequencies
Pogge, R. W.; Kadler, M.; Kerp, J. +3 more
We present a combined radio, optical, and X-ray study of the nearby LINER galaxy NGC 1052. Data from a short (2.3 ks) CHANDRA observation of NGC 1052 reveal the presence of various jet-related X-ray emitting regions, a bright compact core and unresolved knots in the jet structure as well as an extended emitting region inside the galaxy well aligne…