Search Publications
A Steady, Radiative-Shock Method for Computing X-Ray Emission from Colliding Stellar Winds in Close, Massive-Star Binaries
Owocki, S. P.; Antokhin, I. I.; Brown, J. C.
We present a practical, efficient, semianalytic formalism for computing steady state X-ray emission from radiative shocks between colliding stellar winds in relatively close (orbital period up to order tens of days) massive-star, binary systems. Our simplified approach idealizes the individual wind flows as smooth and steady, ignoring the intrinsi…
X-Ray Sources and Their Optical Counterparts in the Globular Cluster M4
Anderson, Scott F.; Kaspi, Victoria M.; Verbunt, Frank +7 more
We report on the Chandra X-Ray Observatory ACIS-S3 imaging observation of the Galactic globular cluster M4 (NGC 6121). We detect 12 X-ray sources inside the core and 19 more within the cluster half-mass radius. The limiting luminosity of this observation is LX~1029 ergs s-1 for sources associated with the cluster, …
The Discovery of an Evolving Dust-scattered X-Ray Halo around GRB 031203
Schartel, N.; Rodríguez-Pascual, P. M.; Santos-Lleó, M. +9 more
We report the first detection of a time-dependent dust-scattered X-ray halo around a gamma-ray burst (GRB). GRB 031203 was observed by XMM-Newton starting 6 hr after the burst. The halo appeared as concentric ringlike structures centered on the GRB location. The radii of these structures increased with time as t1/2, consistent with smal…
Further Multiwavelength Observations of the SSA 22 Lyα-Emitting Blob
Ivison, R. J.; Frayer, D. T.; Scott, D. +4 more
We present new follow-up observations of the submillimeter luminous Lyα-emitting object in the SSA 22 z=3.09 galaxy overdensity, referred to as ``blob 1'' by Steidel and coworkers. In particular, we discuss high-resolution Hubble Space Telescope (HST) optical imaging, Owens Valley Radio Observatory (OVRO) spectral imaging, Keck spectroscopy, Very …
Sensitivity of Acoustic Wave Travel Times to Sound-Speed Perturbations in the Solar Interior
Kosovichev, A. G.; Birch, A. C.; Duvall, T. L., Jr.
For time-distance helioseismology, it is important to establish the relationship between the travel times of acoustic waves propagating between different points on the solar surface through the solar interior and local perturbations to the sound speed in the propagation region. We use the Born approximation to derive a general expression for the l…
Chain Galaxies in the Tadpole Advanced Camera for Surveys Field
Elmegreen, Bruce G.; Elmegreen, Debra Meloy; Sheets, Clara M.
Colors and magnitudes were determined for 69 chain galaxies, 58 other linear structures, 32 normal edge-on galaxies, and all of their large star formation clumps in the Hubble Space Telescope Advanced Camera for Surveys field of the Tadpole galaxy. Redshifts of 0.5-2 are inferred from comparisons with published color-evolution models. The linear g…
The Environment of the Optically Brightest Herbig Ae Star, HD 104237
Apai, D.; Stecklum, B.; Wang, Hongchi +16 more
We investigate the environment of the nearest Herbig Ae star, HD 104237, with a multiwavelength combination of optical coronagraphic, near-IR, and mid-IR imaging supported by optical, UV, and far-ultraviolet spectroscopy. We confirm the presence of T Tauri stars associated with the Herbig Ae star HD 104237, noted by Feigelson et al. We find that t…
Complex Structure of Galaxy Cluster A1689: Evidence for a Merger from X-Ray Data?
Madejski, G. M.; Andersson, K. E.
A1689 is a galaxy cluster at z=0.183 for which previous measurements of its mass by using various techniques gave discrepant results. We present a new detailed measurement of the mass with the data based on X-ray observations with the European Photon Imaging Camera aboard the XMM-Newton Observatory, determined by using an unparameterized deproject…
Solar Subsurface Fluid Dynamics Descriptors Derived from Global Oscillation Network Group and Michelson Doppler Imager Data
Howe, R.; Komm, R.; Hill, F. +4 more
We analyze Global Oscillation Network Group (GONG) and Michelson Doppler Imager (MDI) observations obtained during Carrington rotation 1988 (2002 March 30-April 26) with a ring-diagram technique in order to measure the zonal and meridional flow components in the upper solar convection zone. We derive daily flow maps over a range of depths up to 16…
Wide-Field X-Ray Temperature, Pressure, and Entropy Maps of A754
Finoguenov, Alexis; Henry, J. Patrick; Briel, Ulrich G.
We present a mosaic of XMM-Newton observations of the nearby major-merger cluster A754 that has either a wider field or better spectral or spatial resolution than previous observations. We construct maps of X-ray surface brightness and temperature integrated along the line of sight. From these two primary maps we derive pseudopressure and pseudoen…