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Downflow Motions Associated with Impulsive Nonthermal Emissions Observed in the 2002 July 23 Solar Flare
Shibata, Kazunari; Shimojo, Masumi; Yokoyama, Takaaki +1 more
We present a detailed examination of downflow motions above flare loops observed in the 2002 July 23 flare. The extreme-ultraviolet images obtained with the Transition Region and Coronal Explorer show dark downflow motions (sunward motions) above the postflare loops, not only in the decay phase but also in the impulsive and main phases. We also fo…
X-ray reflection in the narrow-line Seyfert 1 galaxy 1H 0707-495
Vaughan, S.; Fabian, A. C.; Boller, Th. +4 more
We apply a reflection-dominated model to the second XMM-Newton observation of the narrow-line Seyfert 1 galaxy 1H 0707-495. As in the first XMM-Newton observation, a sharp spectral drop is detected with energy that has shifted from 7 to 7.5 keV in two years. The drop is interpreted in terms of relativistically blurred ionized reflection from the a…
The Local Lyα Forest. IV. Space Telescope Imaging Spectrograph G140M Spectra and Results on the Distribution and Baryon Content of H I Absorbers
Shull, J. Michael; Stocke, John T.; Penton, Steven V.
We present Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) G140M spectra of 15 extragalactic targets, which we combine with GHRS/G160M data to examine the statistical properties of the low-z Lyα forest. With STIS, we detect 109 Lyα absorbers at significance level (SL) of >=4 σ over 0.002<z<0.069, with a total reds…
Deflection of coronal mass ejection in the interplanetary medium
Wang, Yuming; Shen, Chenglong; Wang, S. +1 more
A solar coronal mass ejection (CME) is a large-scale eruption of plasma and magnetic fields from the Sun. It is believed to be the main source of strong interplanetary disturbances that may cause intense geomagnetic storms. However, not all front-side halo CMEs can encounter the Earth and produce geomagnetic storms. The longitude distribution of t…
The dynamical mass of the young cluster W3 in NGC 7252. Heavy-weight globular cluster or ultra compact dwarf galaxy?
Saglia, R. P.; Bastian, N.; Maraston, C. +3 more
We have determined the dynamical mass of the most luminous stellar cluster known to date, i.e. object W3 in the merger remnant galaxy NGC 7252. The dynamical mass is estimated from the velocity dispersion measured with the high-resolution spectrograph UVES on VLT. Our result is the astonishingly high velocity dispersion of σ=45 ± 5 km s-1
A Substantial Population of Red Galaxies at z > 2: Modeling of the Spectral Energy Distributions of an Extended Sample
Wuyts, S.; Daddi, E.; Förster Schreiber, N. M. +12 more
We investigate the nature of the substantial population of high-redshift galaxies with Js-Ks>=2.3 colors recently discovered as part of our Faint Infrared Extragalactic Survey (FIRES). This color cut efficiently isolates galaxies at z>2 with red rest-frame optical colors (``distant red galaxies'' [DRGs]). We select J
X-ray flares reveal mass and angular momentum of the Galactic Center black hole
Grosso, N.; Porquet, D.; Predehl, P. +1 more
We have analysed the light curve of the two brightest X-ray flares from the Galactic Center black hole, one flare observed by XMM-Newton on October 3, 2002 (Porquet et al. \cite{P2003}), and the other flare observed by Chandra on October 26, 2000 (Baganoff et al. \cite{B2001}). The power density spectra show five distinct peaks at periods of ∼100 …
The Colors of Dwarf Elliptical Galaxy Globular Cluster Systems, Nuclei, and Stellar Halos
Ferguson, Henry C.; Miller, Bryan W.; Lotz, Jennifer M.
We present the results of a Hubble Space Telescope WFPC2 F555W and F814W survey of 69 dwarf elliptical galaxies (dEs) in the Virgo and Fornax Clusters and Leo Group. The V-I colors of the dE globular clusters, nuclei, and underlying field-star populations are used to trace the dE star formation histories. We find that the dE globular cluster candi…
Hard X-ray view of the past activity of Sgr A* in a natural Compton mirror
Gilfanov, M. R.; Sunyaev, R. A.; Sazonov, S. Yu. +6 more
We report the association of the recently discovered hard X-ray source IGR J17475-2822 with the giant molecular cloud Sgr B2 in the Galactic Center region. The broad band (3-200 keV) spectrum of the source constructed from data of different observatories strongly supports the idea that the X-ray emission of Sgr B2 is Compton scattered and reproces…
Observable Properties of the Breakout Model for Coronal Mass Ejections
Lynch, B. J.; MacNeice, P. J.; Antiochos, S. K. +2 more
We compare the ``magnetic breakout'' model for coronal mass ejections (CMEs) with observed general properties of CMEs by analyzing in detail recent high-resolution MHD simulations of a complete breakout CME. The model produces an eruption with a three-part plasma density structure that shows a bright circular rim outlining a dark central cavity in…