Search Publications
Polar Field Reversal Observations with Hinode
Ishikawa, R.; Tsuneta, S.; Orozco Suárez, D. +3 more
We have been monitoring yearly variation in the Sun's polar magnetic fields with the Solar Optical Telescope aboard Hinode to record their evolution and expected reversal near the solar maximum. All magnetic patches in the magnetic flux maps are automatically identified to obtain the number density and magnetic flux density as a function of the to…
Large-scale Motions in the Perseus Galaxy Cluster
Simionescu, A.; Fabian, A. C.; Allen, S. W. +6 more
By combining large-scale mosaics of ROSAT PSPC, XMM-Newton, and Suzaku X-ray observations, we present evidence for large-scale motions in the intracluster medium of the nearby, X-ray bright Perseus Cluster. These motions are suggested by several alternating and interleaved X-ray bright, low-temperature, low-entropy arcs located along the east-west…
Instantaneous Starburst of the Massive Clusters Westerlund 1 and NGC 3603 YC
Henning, Thomas; Da Rio, Nicola; Gennaro, Mario +9 more
We present a new method to determine the age spread of resolved stellar populations in a starburst cluster. The method relies on a two-step process. In the first step, kinematic members of the cluster are identified based on multi-epoch astrometric monitoring. In the second step, a Bayesian analysis is carried out, comparing the observed photometr…
Herschel/HIFI Discovery of HCl+ in the Interstellar Medium
Falgarone, E.; Godard, B.; Teyssier, D. +12 more
The radical ion HCl+, a key intermediate in the chlorine chemistry of the interstellar gas, has been identified for the first time in the interstellar medium with the Herschel Space Observatory's Heterodyne Instrument for the Far-Infrared. The ground-state rotational transition of H35Cl+, 2Π3/2
Binaries among Debris Disk Stars
Zuckerman, B.; Rodriguez, David R.
We have gathered a sample of 112 main-sequence stars with known debris disks. We collected published information and performed adaptive optics observations at Lick Observatory to determine if these debris disks are associated with binary or multiple stars. We discovered a previously unknown M-star companion to HD 1051 at a projected separation of …
Optical Emission of the Ultraluminous X-Ray Source NGC 5408 X-1: Donor Star or Irradiated Accretion Disk?
Kaaret, P.; Tao, L.; Corbel, S. +3 more
We obtained three epochs of simultaneous Hubble Space Telescope (HST)/Wide Field Camera 3 and Chandra observations of the ultraluminous X-ray source (ULX) NGC 5408 X-1. The counterpart of the X-ray source is seen in all HST filters, from the UV through the near-IR (NIR), and for the first time, we resolve the optical nebula around the ULX. We iden…
Forward Cascade of Whistler Turbulence: Three-dimensional Particle-in-cell Simulations
Gary, S. Peter; Chang, Ouliang; Wang, Joseph
This manuscript describes the first ensemble of three-dimensional (3D) particle-in-cell (PIC) plasma simulations of whistler turbulence. The computational model represents a collisionless, homogeneous, magnetized plasma on which an initial spectrum of relatively long wavelength whistler fluctuations is imposed. The simulations represent a range of…
A Data-driven Model for the Global Coronal Evolution
Wu, S. T.; Feng, Xueshang; Jiang, Chaowei +2 more
This work is devoted to the construction of a data-driven model for the study of the dynamic evolution of the global corona that can respond continuously to the changing of the photospheric magnetic field. The data-driven model consists of a surface flux transport (SFT) model and a global three-dimensional (3D) magnetohydrodynamic (MHD) coronal mo…
Investigating Slim Disk Solutions for HLX-1 in ESO 243-49
Gehrels, N.; Braito, V.; Farrell, S. A. +7 more
The hyperluminous X-ray source HLX-1 in the galaxy ESO 243-49, currently the best intermediate-mass black hole (BH) candidate, displays spectral transitions similar to those observed in Galactic BH binaries, but with a luminosity 100-1000 times higher. We investigated the X-ray properties of this unique source by fitting multi-epoch data collected…
Pulsed Gamma Rays from the Original Millisecond and Black Widow Pulsars: A Case for Caustic Radio Emission?
Camilo, F.; Gargano, F.; Grove, J. E. +25 more
We report the detection of pulsed gamma-ray emission from the fast millisecond pulsars (MSPs) B1937+21 (also known as J1939+2134) and B1957+20 (J1959+2048) using 18 months of survey data recorded by the Fermi Large Area Telescope and timing solutions based on radio observations conducted at the Westerbork and Nançay radio telescopes. In addition, …