Search Publications
Estimation of the Reconnection Electric Field in the 2003 October 29 X10 Flare
Krucker, Säm; Cheng, C. Z.; Yang, Ya-Hui +1 more
The electric field in the reconnecting current sheet of the 2003 October 29 X10 flare is estimated to be a few kV m-1 in this study, based on the rate of change in the photospheric magnetic flux in the newly brightened areas of Transition Region and Coronal Explorer (TRACE) UV ribbons. For comparison, the motion speed of Reuven Ramaty H…
The Disappearing Solar Filament of 2003 June 11: A Three-body Problem
Panasenco, O.; Balasubramaniam, K. S.; Pevtsov, A. A. +2 more
The eruption of a large quiescent filament on 2003 June 11 was preceded by the birth of a nearby active region—a common scenario. In this case, however, the filament lay near a pre-existing active region and the new active region did not destabilize the filament by direct magnetic connection. Instead it appears to have done so indirectly via magne…
Analysis of SOHO/MDI and TRACE Observations of Sunspot Torsional Oscillation in AR10421
Kosovichev, A. G.; Gopasyuk, O. S.
Rotation of the leading sunspot of active region NOAA 10421 was investigated using magnetograms and Dopplergrams from the MDI instrument of the Solar and Heliospheric Observatory, and white-light images from the Transition Region and Coronal Explorer (TRACE). The vertical, radial, and azimuthal axisymmetrical components of both magnetic and veloci…
A Hard and Variable X-ray Emission from the Massive Emission-line Star HD 157832
Motch, C.; Lopes de Oliveira, R.
We report the discovery with XMM-Newton of a hard-thermal (T ~ 130 MK) and variable X-ray emission from the Be star HD 157832, a new member of the puzzling class of γ-Cas-like Be/X-ray systems. Recent optical spectroscopy reveals the presence of a large/dense circumstellar disk seen at intermediate/high inclination. With a B1.5V spectral type, HD …
Formation of a Propeller Structure by a Moonlet in a Dense Planetary Ring
Kokubo, Eiichiro; Michikoshi, Shugo
The Cassini spacecraft discovered a propeller-shaped structure in Saturn's A ring. This propeller structure is thought to be formed by gravitational scattering of ring particles by an unseen embedded moonlet. Self-gravity wakes are prevalent in dense rings due to gravitational instability. Strong gravitational wakes affect the propeller structure.…
An Hα Nuclear Spiral Structure in the E0 Active Galaxy Arp 102B
Robinson, Andrew; Marconi, Alessandro; Axon, David J. +5 more
We report the discovery of a two-armed mini-spiral structure within the inner kiloparsec of the E0 LINER/Seyfert 1 galaxy Arp 102B. The arms are observed in Hα emission and located east and west of the nucleus, extending up to ≈1 kpc from it. We use narrow-band imaging from the Hubble Space Telescope Advanced Camera for Surveys, in combination wit…
Observations of Five-minute Solar Oscillations in the Corona Using the Extreme Ultraviolet Spectrophotometer (ESP) On Board the Solar Dynamics Observatory Extreme Ultraviolet Variability Experiment (SDO/EVE)
Kosovichev, A. G.; Didkovsky, L.; Judge, D. +2 more
We report on the detection of oscillations in the corona in the frequency range corresponding to five-minute acoustic modes of the Sun. The oscillations have been observed using soft X-ray measurements from the Extreme Ultraviolet Spectrophotometer (ESP) of the Extreme Ultraviolet Variability Experiment on board the Solar Dynamics Observatory. The…
A Unique X-Ray Unabsorbed Seyfert 2 Galaxy: IRAS F01475-0740
Wang, Jun-Xian; Yang, Huan; Huang, Ya-Fang +2 more
X-ray unabsorbed Seyfert 2 galaxies appear to have X-ray absorption column densities that are too low (N H < 1022 cm-2) to explain the absence of broad emission lines in their optical spectra, challenging the standard active galactic nucleus (AGN) unification model. In this Letter, we report Suzaku exposure on t…
Mid-J CO Emission from NGC 891: Microturbulent Molecular Shocks in Normal Star-forming Galaxies
Tucker, C.; Stacey, G. J.; Brisbin, D. +4 more
We have detected the CO(6-5), CO(7-6), and [C I] 370 µm lines from the nuclear region of NGC 891 with our submillimeter grating spectrometer ZEUS on the Caltech Submillimeter Observatory. These lines provide constraints on photodissociation region (PDR) and shock models that have been invoked to explain the H2 S(0), S(1), and S(2)…
Supermodel Analysis of the Hard X-ray Excess in the Coma Cluster
Orlandini, M.; Lapi, A.; Bonamente, M. +1 more
The Supermodel (SM) provides an accurate description of the thermal contribution by the hot intracluster plasma which is crucial for the analysis of the hard excess. In this paper, the thermal emissivity in the Coma cluster is derived starting from the intracluster gas temperature and density profiles obtained by the SM analysis of X-ray observabl…