Search Publications
Stellar Populations of Luminous Evolved Galaxies at z ~ 1.5
McGrath, Elizabeth J.; Stockton, Alan; Canalizo, Gabriela
Observational evidence has been mounting over the past decade that at least some luminous (~2L*) galaxies have formed nearly all of their stars within a short period of time, only (1-2)×109 yr after the big bang. These are examples of the first major episodes of star formation in the universe and provide insights into the formation of t…
SMA High Angular Resolution Imaging of the Lensed Quasar APM 08279+5255
Iono, D.; Wilner, D. J.; Krips, M. +4 more
We present Submillimeter Array observations of the z=3.91 gravitationally lensed broad absorption line quasar APM 08279+5255 which spatially resolve the 1.0 mm (200 µm rest frame) dust continuum emission. At 0.4" resolution, the emission is separated into two components, a stronger, extended one to the northeast (46+/-5 mJy) and a weaker, co…
Dust Rings and Filaments around the Isolated Young Star V1331 Cygni
Quanz, S. P.; Apai, D.; Henning, Th.
We characterize the small- and large-scale environment of the young star V1331 Cygni with high-resolution HST WFPC2 and Digitized Sky Survey images. In addition to a previously known outer dust ring (~30'' in diameter), the WFPC2 scattered light image reveals an inner dust ring for the first time. This ring has a maximum radius of ~6.5<…
Reconstructing Spherical Nonlinear Force-free Field in the Solar Corona
Wu, S. T.; Zhang, H. Q.; Fang, C. +3 more
We present a spherical nonlinear force-free field (NFFF) reconstructing method based on the photospheric vector magnetograms. The importance of this method is its ability to reveal the NFFF configurations, which is necessary for understanding the physical mechanisms of the initiation of the large-scale solar eruptions, such as coronal mass ejectio…
Velocity Profiles in the Solar Corona from Multi-Instrument Observations
Lamy, P.; Lallement, R.; Quémerais, E. +1 more
We present a method to derive outflow velocities in the solar corona using different data sets, including solar wind mass flux coming from the SWAN SOHO instrument, electron density values from LASCO-C2, and interplanetary solar wind velocities derived from ground-based interplanetary scintillation observations (IPS). In a first step, we combine t…
Evolution of Magnetic Nonpotentiality in NOAA AR 10486
Liu, Y.; Zhang, H.; Kurokawa, H. +2 more
The active region NOAA 10486 was one of the most flare-productive regions during solar cycle 23. In this paper, we focus our analysis on the daily evolution of magnetic nonpotentiality for this region from 2003 October 26 to October 30. Daily averaged values of three nonpotential parameters: magnetic shear angle, line-of-sight current, and current…
X-Ray Observations and Infrared Identification of the Transient 7.8 s X-Ray Binary Pulsar XTE J1829-098
Gotthelf, E. V.; Halpern, J. P.
XMM-Newton and Chandra observations of the transient 7.8 s pulsar XTE J1829-098 are used to characterize its pulse shape and spectrum, and to facilitate a search for an optical or infrared counterpart. In outburst, the absorbed, hard X-ray spectrum with Γ=0.76+/-0.13 and NH=(6.0+/-0.6)×1022 cm-2 is typical of X-ray…
The Nearby Young Visual Binary HIP 115147 and Its Common Proper Motion Companion LSPM J2322+7847
Makarov, V. V.; Zacharias, N.; Hennessy, G. S. +2 more
We report a late M-type, common proper motion companion to a nearby young visual binary HIP 115147 (V368 Cep), separated by 963" from the primary K0 dwarf. This optically dim star was identified as a candidate high proper motion, nearby dwarf LSPM J2322+7847 by Lépine in 2005. The wide companion is one of the latest post-T Tauri low-mass stars fou…
Application of an XMM-Newton EPIC Monte Carlo Technique to Analysis and Interpretation of Data for the Abell 1689, RX J0658-55, and Centaurus Clusters of Galaxies
Peterson, J. R.; Madejski, G.; Andersson, K.
We propose a new Monte Carlo method to study extended X-ray sources with the European Photon Imaging Camera (EPIC) aboard XMM-Newton. The smoothed particle inference (SPI) technique, described in a companion paper, is applied here to the EPIC data for the clusters of galaxies Abell 1689, Centaurus, and RX J0658-55 (the ``bullet cluster''). We aim …
Density Dependence of the Mass Function of Globular Star Clusters in the Sombrero Galaxy and Its Dynamical Implications
Fall, S. Michael; Chandar, Rupali; McLaughlin, Dean E.
We have constructed the mass function of globular star clusters in the Sombrero galaxy in bins of different internal half-mass density ρh and projected galactocentric distance R. This is based on the published measurements of the magnitudes and effective radii of the clusters by Spitler and coworkers in BVR images taken with the ACS on …