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Discovery of Another Peculiar Radial Distribution of Blue Stragglers in Globular Clusters: The Case of 47 Tucanae
Ferraro, Francesco R.; Sills, Alison; Sabbi, Elena +3 more
We have used the high-resolution Wide Field Planetary Camera (WFPC2) on the Hubble Space Telescope (HST) and wide-field ground-based observations to construct a catalog of blue straggler stars (BSSs) in the globular cluster 47 Tuc spanning the entire radial extent of the cluster. The BSS distribution is highly peaked in the cluster center, rapidly…
Photometric Redshifts for Galaxies in the GOODS Southern Field
Cimatti, A.; Daddi, E.; Wolf, C. +19 more
We use extensive multiwavelength photometric data from the Great Observatories Origins Deep Survey to estimate photometric redshifts for a sample of 434 galaxies with spectroscopic redshifts in the Chandra Deep Field-South. Using the Bayesian method, which incorporates redshift/magnitude priors, we estimate photometric redshifts for galaxies in th…
Influence of coronal mass ejection interaction on propagation of interplanetary shocks
Howard, R. A.; Gopalswamy, N.; Michalek, G. +3 more
We studied 91 interplanetary (IP) shocks associated with coronal mass ejections (CMEs) originating within about ±30° in longitude and latitude from the center of the Sun during 1997-2002. These CMEs cover a wide range of initial speeds of about 120 to 2400 kms-1 and they also include a special population of 25 interacting CMEs. This stu…
The Structure of the Local Interstellar Medium. II. Observations of D I, C II, N I, O I, Al II, and Si II toward Stars within 100 Parsecs
Redfield, Seth; Linsky, Jeffrey L.
Moderate- and high-resolution measurements (λ/Δλ>~40,000) of interstellar resonance lines of D I, C II, N I, O I, Al II, and Si II (hereafter called light ions) are presented for all available observed targets located within 100 pc that also have high-resolution observations of interstellar Fe II or Mg II (heavy ions) lines. All spectra were ob…
The Association of Big Flares and Coronal Mass Ejections: What Is the Role of Magnetic Helicity?
Andrews, M. D.; Nindos, A.
Recently, M. D. Andrews found that approximately 40% of M-class flares between 1996 and 1999, classified according to GOES X-ray flux, are not associated with coronal mass ejections (CMEs). Using 133 events from his data set for which suitable photospheric magnetograms and coronal images were available, we studied the preflare coronal helicity of …
A panoramic Hα imaging survey of the z= 0.4 cluster Cl0024.0+1652 with Subaru
Smail, Ian; Kodama, Tadayuki; Nakata, Fumiaki +2 more
We employ panoramic, multicolour (BRz') and narrow-band Hα imaging of the cluster Cl0024.0+1652 (z= 0.39) from Subaru covering a ~30-arcmin field, to determine cluster membership and star formation rates for a large sample of galaxies across a wide field in the cluster, ~10 Mpc. We use photometric redshifts to identify cluster members, and statist…
Iron charge state distributions as an indicator of hot ICMEs: Possible sources and temporal and spatial variations during solar maximum
Lepri, S. T.; Zurbuchen, T. H.
It has been shown that Fe charge states greater than and equal to 16 are often observed in the presence of interplanetary coronal mass ejections (ICMEs) at 1 AU. These elevated charge states, representative of hot source regions on the Sun, provide an identifier of ICMEs independent of expansion processes and heliocentric distance. Using this new …
Three-Dimensional Structure of the Active Region Photosphere as Revealed by High Angular Resolution
Lites, B. W.; Title, A. M.; Berger, T. E. +1 more
Blue continuum images of active regions at ∼ 60° from the center of the solar disk obtained with the new Swedish 1-m Solar Telescope reveal heretofore unreported structure of the magnetized solar atmosphere. Perhaps the most striking aspect of these images is that, at an angular resolution of 0.12″, they show clearly the three-dimensional structur…
Exploring the complex X-ray spectrum of NGC 4051
King, A. R.; Reeves, J. N.; Page, K. L. +1 more
Archival XMM-Newton data on the nearby Seyfert galaxy NGC 4051, taken in relatively high- and low-flux states, offer a unique opportunity to explore the complexity of its X-ray spectrum. We find the hard X-ray band to be significantly affected by reflection from cold matter, which can also explain a non-varying, narrow Fe K fluorescent line. We in…
A transition in the accretion properties of radio-loud active nuclei
Marchesini, Danilo; Ferrarese, Laura; Celotti, Annalisa
We present evidence for the presence of a transition in the accretion properties of radio-loud sources. For a sample of radio galaxies and radio-loud quasars, selected based on their extended radio properties, the accretion rate is estimated from the black hole mass and nuclear luminosity. The inferred distribution is bimodal, with a paucity of so…