Search Publications
Enigma of a Flare Involving Multiple-Loop Interactions: Emerging, Colliding Loops or Magnetic Breakout?
Holman, Gordon D.; Dennis, Brian R.; Sui, Linhui
We present observations of a C9.4 flare on 2002 June 2 in EUV (TRACE), X-rays (RHESSI), and Hα (Meudon and Ondrejov) showing evidence for multiple-loop interactions as the cause of the flare. The multiwavelength data reveal some striking phenomena that can be used to test different models for solar eruptive events: (1) involvement of a quadrupolar…
Is There Any Evident Effect of Coronal Holes on Gradual Solar Energetic Particle Events?
Wang, Yuming; Shen, Chenglong; Wang, S. +1 more
Gradual solar energetic particle (SEP) events are thought to be produced by shocks, which are usually driven by fast coronal mass ejections (CMEs). The strength and magnetic field configuration of the shock are considered the two most important factors for shock acceleration. Theoretically, both of these factors should be unfavorable for producing…
The Possible z=0.83 Precursors of z=0, M* Early-Type Cluster Galaxies
Kelson, D. D.; Ford, H. C.; Demarco, R. +8 more
We examine the distribution of stellar masses of galaxies in MS 1054.4-0321 and Cl 0152.7-1357, two X-ray-selected clusters of galaxies at z=0.83. Our stellar mass estimates, from spectral energy distribution fitting, reproduce the dynamical masses as measured from velocity dispersions and half-light radii with a scatter of 0.2 dex in the mass for…
The X-Ray Properties of Active Galactic Nuclei with Double-peaked Balmer Lines
Brandt, W. N.; Schneider, Donald P.; Eracleous, Michael +2 more
Double-peaked Balmer line profiles originate in the accretion disks of a few percent of optically selected active galactic nuclei (AGNs). The reasons behind the strong low-ionization line emission from the accretion disks of these objects are still uncertain. In this paper, we characterize the X-ray properties of 39 double-peaked Balmer line AGNs,…
Variations in the D/H Ratio of Extended Sight Lines from Far Ultraviolet Spectroscopic Explorer Observations
Hébrard, Guillaume; Oliveira, Cristina M.
We use new FUSE data to determine the column densities of interstellar D I, N I, O I, Fe II, and H2 along the HD 41161 and HD 53975 sight lines. Together with N(H I) from the literature, we derive D/H, N/H, and O/H ratios. These sight lines have logN(H I)>21.00 and probe gas up to ~1300 pc, allowing us to determine the gas-phase D/H …
The Prediction of a Supersoft X-Ray Phase during the 2006 Outburst of RS Ophiuchi
Kato, Mariko; Hachisu, Izumi
RS Ophiuchi is one of the well-observed recurrent novae and also a candidate progenitor of Type Ia supernovae. Its sixth recorded outburst was discovered on 2006 February 12. Detection of a supersoft X-ray phase will provide us with a firm confirmation of hydrogen shell burning on the white dwarf, and its turn-on/turnoff dates strongly constrain t…
Coronal Magnetic Field Topology over Filament Channels: Implication for Coronal Mass Ejection Initiations
Luhmann, Janet; Li, Yan
The magnetic field topology at the coronal mass ejection (CME) source regions has been one of the major focuses of CME initiation models. While the ``breakout'' model requires a quadrupolar magnetic topology in the solar corona to enable an eruption, other models have shown that a bipolar magnetic topology can be the source region of a CME. In thi…
XMM-Newton Detection of X-Ray Emission from the Compact Steep-Spectrum Radio Galaxy 3C 303.1
O'Dea, Christopher P.; Baum, Stefi; Worrall, D. M. +3 more
Using XMM-Newton we detect faint unresolved X-ray emission from the compact steep-spectrum radio galaxy 3C 303.1. We detect a thermal component at kT~=0.8 keV, which seems likely to be produced in the interstellar medium (ISM) of the host galaxy. There is evidence for a second component in the spectrum whose nature is currently ambiguous. Plausibl…
A Genuine Intermediate-Age Globular Cluster in M33
Chandar, Rupali; Sarajedini, Ata; Goudfrooij, Paul +1 more
We present deep integrated-light spectroscopy of nine M33 globular clusters taken with the Hectospec instrument at the MMT Observatory. Based on our spectroscopy and previous deep color-magnitude diagrams obtained with HST WFPC2, we present evidence for the presence of a genuine intermediate-age globular cluster in M33. The analysis of Lick line i…
The Interstellar N/O Abundance Ratio: Evidence for Local Infall?
Meyer, David M.; Lauroesch, James T.; Knauth, David C.
Sensitive measurements of the interstellar gas-phase oxygen abundance have revealed a slight oxygen deficiency (~15%) toward stars within 500 pc of the Sun as compared to more distant sight lines. Recent FUSE observations of the interstellar gas-phase nitrogen abundance indicate larger variations, but no trends with distance were reported due to t…