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Radially Inflowing Molecular Gas in NGC 1275 Deposited by an X-Ray Cooling Flow in the Perseus Cluster
Lim, Jeremy; Dinh-V-Trung; Ao, YiPing
We have imaged in CO(2-1) the molecular gas in NGC 1275 (Perseus A), the cD galaxy at the center of the Perseus Cluster, at a spatial resolution of ~1 kpc over a central region of radius ~10 kpc. Per A is known to contain ~1.3 × 1010 M⊙ of molecular gas, which has been proposed to be captured from mergers with or ram pressure…
Occurrence of reconnection jets at the dayside magnetopause: Double Star observations
RèMe, H.; Cao, J. B.; Carr, C. M. +7 more
We present a statistical study on reconnection occurrence at the dayside magnetopause performed using the Double Star TC1 plasma and magnetic field data. We examined the magnetopause crossings that occurred during the first year of the mission in the 0600-1800 LT interval and we identified plasma flows, at the magnetopause or in the boundary layer…
X-Ray Spectroscopy of the 2006 Outburst of RS Ophiuchi
Orio, Marina; Still, Martin; Nelson, Thomas +3 more
We present X-ray grating spectra of the recurrent nova RS Ophiuchi during its 2006 outburst, obtained with XMM-Newton and Chandra. For the first month after optical maximum, the X-ray spectrum was hard and dominated by emission lines of H-like and He-like ions. The X-ray luminosity was 2.4 × 1036 ergs s-1 in the 0.33-10 keV r…
Delving Deeper into the Tumultuous Lives of Galactic Dwarfs: Modeling Star Formation Histories
Dolphin, Andrew E.; Skillman, Evan D.; Holtzman, Jon A. +3 more
The paucity of observed dwarf galaxies in the Local Group relative to the abundance of predicted dark matter halos remains one of the greatest puzzles of the ΛCDM paradigm. Solving this puzzle now requires not only matching the numbers of objects but also understanding the details of their star formation histories. We present a summary of such his…
Large-scale dynamics of Saturn's magnetopause: Observations by Cassini
Russell, C. T.; Dougherty, M. K.; Jackman, C. M. +4 more
The long-term statistical behavior of the large-scale structure of Saturn's magnetosphere has been investigated. Established statistical techniques for Jupiter have been applied to the kronian system, employing Cassini magnetometer data and a new empirical shape model of the magnetopause based on these data. The resulting distribution of standoff …
Spectroscopy of clusters in the ESO distant cluster survey (EDisCS). II.. Redshifts, velocity dispersions, and substructure for clusters in the last 15 fields
Moustakas, J.; Pelló, R.; White, S. D. M. +17 more
Aims: We present spectroscopic observations of galaxies in 15 survey fields as part of the ESO Distant Cluster Survey (EDisCS). We determine the redshifts and velocity dispersions of the galaxy clusters located in these fields, and we test for possible substructure in the clusters.
Methods: We obtained multi-object mask spectroscopy using the …
Structural Properties of Ultra-Compact Dwarf Galaxies in the Fornax and Virgo Clusters
Peng, C. Y.; Hilker, M.; Evstigneeva, E. A. +6 more
We present a detailed analysis of high-resolution two-band Hubble Space Telescope Advanced Camera for Surveys imaging of 21 ultra-compact dwarf (UCD) galaxies in the Virgo and Fornax Clusters. The aim of this work is to test two formation hypotheses for UCDs—whether they are bright globular clusters (GCs) or stripped ("threshed") early-type dwarf …
Cooling of the Crust in the Neutron Star Low-Mass X-Ray Binary MXB 1659-29
Miller, Jon M.; Cackett, Edward M.; Wijnands, Rudy +2 more
In quasi-persistent neutron star transients, long outbursts cause the neutron star crust to be heated out of thermal equilibrium with the rest of the star. During quiescence, the crust then cools back down. Such crustal cooling has been observed in two quasi-persistent sources: KS 1731-260 and MXB 1659-29. Here we present an additional Chandra obs…
Radio-Quiet Fast and Wide Coronal Mass Ejections
Kaiser, M. L.; Howard, R. A.; Gopalswamy, N. +5 more
We report on the properties of radio-quiet (RQ) and radio-loud (RL) coronal mass ejections (CMEs) that are fast and wide (FW). RQ CMEs lack type II radio bursts in the metric and decameter-hectometric (DH) wavelengths. RL CMEs are associated with metric or DH type II bursts. We found that ~40% of the FW CMEs from 1996 to 2005 were RQ. The RQ CMEs …
Tracing a disk wind in NGC 3516
Turner, T. J.; Kraemer, S. B.; Reeves, J. N. +1 more
Context: X-ray spectra of AGN often contain signatures indicative of absorption in multiple layers of gas whose ionization-state and covering fraction may vary with time. It has been unclear to date how much of the observed X-ray spectral and timing behavior in AGN can be attributed to variations in absorption, versus variations in the strengths o…