Search Publications
Relativistic Iron Line Emission from the Neutron Star Low-Mass X-Ray Binary 4U 1636-536
Kaaret, Philip; Pandel, Dirk; Corbel, Stephane
We present an analysis of XMM-Newton and RXTE data from three observations of the neutron star LMXB 4U 1636-536. The X-ray spectra show clear evidence of a broad, asymmetric iron emission line extending over the energy range 4-9 keV. The line profile is consistent with relativistically broadened Fe Kα emission from the inner accretion disk. The Fe…
Outbursts Large and Small from EXO 2030+375
Finger, Mark H.; Wilson, Colleen A.; Camero-Arranz, Ascensión
During the summer of 2006, the accreting X-ray pulsar EXO 2030+375 underwent its first giant outburst since its discovery in 1985. Our observations include the first ever of the rise of a giant outburst of EXO 2030+375. EXO 2030+375 was monitored daily with the Rossi X-Ray Timing Explorer (RXTE) from 2006 June to 2007 May. During the giant outburs…
Effects of Scattering on Radio Emission from the Quiet Sun at Low Frequencies
MacDowall, R. J.; Thejappa, G.
The observations of the quiet Sun at meter and decameter wavelengths show that its brightness temperatures can be ~1 order of magnitude lower than the expected values of 106 K and the apparent diameters can be very large. We examine whether this unusual behavior is due to refraction in the smoothly varying coronal plasma and scattering …
Detection of a Hot Subdwarf Companion to the Be Star FY Canis Majoris
Gies, Douglas R.; Peters, Geraldine J.; Grundstrom, Erika D. +1 more
The rapid rotation of Be stars may be caused in some cases by past mass and angular momentum accretion in an interacting binary in which the mass donor is currently viewed as a small, hot subdwarf stripped of its outer envelope. Here we report on the spectroscopic detection of such a subdwarf in the Be binary system FY Canis Majoris from the analy…
Understanding the 8 µm versus Paα Relationship on Subarcsecond Scales in Luminous Infrared Galaxies
Colina, Luis; Alonso-Herrero, Almudena; Díaz-Santos, Tanio +3 more
This work explores in detail the relation between the 8 µm and the Paα emissions for 122 H II regions identified in a sample of 10 low-z LIRGs with nearly constant metallicity [12 + log (O/H) ~ 8.8]. We use Gemini T-ReCS high spatial resolution (lesssim0.4''~120 pc for the average distance of 60 Mpc of our sample) mid-infrared imaging (at 8.…
Solar Magnetic Tracking. II. The Apparent Unipolar Origin of Quiet-Sun Flux
Lamb, D. A.; DeForest, C. E.; Hagenaar, H. J. +2 more
We investigate the origin of small-scale flux concentrations in the quiet Sun. In apparent violation of the physical requirement for flux balance, 94% of the features containing newly detected flux are unipolar at a resolution of 1.2''. We analyze 2619 of these apparent unipolar emergences in an image sequence from the SOHO MDI magnetograph and co…
A Test of Three Optical Flow Techniques—LCT, DAVE, and NAVE
Chae, Jongchul; Sakurai, Takashi
A time sequence of high-quality images currently produced by high-resolution observations either from the ground or in space may be utilized to determine the transverse flow field on the plane of the sky with the help of optical flow techniques. We have examined the performance of three different methods—a well-known technique called local correla…
Observational Test of Coronal Magnetic Field Models. I. Comparison with Potential Field Model
Liu, Yu; Lin, Haosheng
Recent advances have made it possible to obtain two-dimensional line-of-sight magnetic field maps of the solar corona from spectropolarimetric observations of the Fe XIII 1075 nm forbidden coronal emission line. Together with the linear polarization measurements that map the azimuthal direction of the coronal magnetic field projected in the plane …
X-Ray and Near-IR Variability of the Anomalous X-Ray Pulsar 1E 1048.1-5937: From Quiescence Back to Activity
Kaspi, Victoria M.; Bassa, Cees; Woods, Peter M. +3 more
We report on new and archival X-ray and near-IR observations of the anomalous X-ray pulsar 1E 1048.1-5937 performed between 2001 and 2007 with the Rossi X-Ray Telescope Explorer (RXTE), the Chandra X-Ray Observatory, the Swift Gamma-Ray Burst Explorer, the Hubble Space Telescope (HST), and the Very Large Telescope. Monitoring with RXTE revealed th…
Constraining Cosmic Evolution of Type Ia Supernovae
Becker, A. C.; Sollerman, J.; Spyromilio, J. +27 more
We present a large-scale effort of creating composite spectra of high-redshift SNe Ia and comparing them to low-redshift counterparts in an attempt to understand possible cosmic evolution of SNe Ia, which has major implications for studies of dark energy. Through the ESSENCE project, we have obtained 107 spectra of 88 high-redshift SNe Ia with exc…