Search Publications
Extended Magnetospheres in Pre-main-sequence Evolution: From T Tauri Stars to the Brown Dwarf Limit
Gómez de Castro, Ana I.; Marcos-Arenal, Pablo
Low-mass pre-main-sequence stars, i.e., T Tauri stars (TTSs), strongly radiate at high energies, from X-rays to the ultraviolet (UV). This excess radiation with respect to main-sequence cool stars (MSCSs) is associated with the accretion process, i.e., it is produced in the extended magnetospheres, in the accretion shocks on the stellar surface, a…
A New Microlensing Event in the Doubly Imaged Quasar Q 0957+561
Kochanek, C. S.; Harris, Hugh C.; Fadely, Ross +6 more
We present evidence for ultraviolet/optical microlensing in the gravitationally lensed quasar Q 0957+561. We combine new measurements from our optical monitoring campaign at the United States Naval Observatory, Flagstaff, with measurements from the literature and find that the time-delay-corrected r-band flux ratio mA - mB ha…
Numerical Simulation of Three-dimensional Asymmetric Reconnection and Application to a Physical Mechanism of Penumbral Microjets
Shibata, Kazunari; Isobe, Hiroaki; Nakamura, Naoki
Three-dimensional (3D) component reconnection, where reconnecting field lines are not perfectly anti-parallel, is studied with a 3D magnetohydrodynamic simulation. In particular, we consider the asymmetry of the field strength of the reconnecting field lines. As the asymmetry increases, the generated reconnection jet tends to be parallel to strong…
An Over-and-out Halo Coronal Mass Ejection Driven by the Full Eruption of a Kinked Filament
Yang, Bo; Yang, Jiayan; Bi, Yi +5 more
Over-and-out coronal mass ejections (CMEs) represent a broad class of CMEs that come from flare-producing magnetic explosions of various sizes but are laterally far offset from the flare, and their productions can be depicted by the magnetic-arch-blowout scenario. In this paper, we present observations of an over-and-out halo CME from the full eru…
The Ultraviolet Spectral Energy Distributions of Quiescent Black Holes and Neutron Stars
Robinson, E. L.; Hynes, R. I.
We present Hubble Space Telescope/Advanced Camera for Surveys ultraviolet photometry of three quiescent black hole X-ray transients, X-ray Nova Muscae 1991 (GU Mus), GRO J0422+32 (V518 Per), and X-ray Nova Vel 1993 (MM Vel), and one neutron star system, Aql X-1. These are the first quiescent UV detections of these objects. All are detected at a mu…
Identifying the Radio Bubble Nature of the Microwave Haze
Dobler, Gregory
Using seven-year data from the Wilkinson Microwave Anisotropy Probe, I identify a sharp "edge" in the microwave haze at high southern Galactic latitude (-55° < b < -35°) that is spatially coincident with the southern edge of the "Fermi haze/bubbles." This finding proves conclusively that the edge in the gamma rays is real (and not a processi…
Nonlinear Force-free Modeling of a Three-dimensional Sigmoid Observed on the Sun
Choe, G. S.; Inoue, S.; Magara, T. +1 more
In this work, we analyze the characteristics of the three-dimensional magnetic structure of a sigmoid observed over an active region (AR 10930) and followed by X-class flares. This is accomplished by combining a nonlinear force-free field (NLFFF) model of a coronal magnetic field and the high-resolution vector-field measurement of a photospheric m…
Analysis of GRB 080319B and GRB 050904 within the Fireshell Model: Evidence for a Broader Spectral Energy Distribution
Izzo, L.; Bernardini, M. G.; Patricelli, B. +5 more
The observation of GRB 080319B, with an isotropic energy E iso = 1.32 × 1054 erg, and GRB 050904, with E iso = 1.04 × 1054 erg, offers the possibility of studying the spectral properties of the prompt radiation of two of the most energetic gamma-ray bursts (GRBs). This allows us to probe the validity of …
12 Years of X-Ray Variability in M31 Globular Clusters, Including 8 Black Hole Candidates, as Seen by Chandra
Murray, S. S.; Barnard, R.; Garcia, M.
We examined 134 Chandra observations of the population of X-ray sources associated with globular clusters (GCs) in the central region of M31. These are expected to be X-ray binary systems (XBs), consisting of a neutron star or black hole accreting material from a close companion. We created long-term light curves for these sources, correcting for …
Suzaku X-Ray Follow-up Observations of Seven Unassociated Fermi-LAT Gamma-Ray Sources at High Galactic Latitudes
Cheung, C. C.; Guillemot, L.; Kataoka, J. +8 more
We report on our second-year campaign of X-ray follow-up observations of unidentified Fermi Large Area Telescope (LAT) γ-ray sources at high Galactic latitudes (|b| > 10°) using the X-ray Imaging Spectrometer on board the Suzaku X-ray Observatory. In this second year of the project, seven new targets were selected from the First Fermi-LAT Catal…