Search Publications
Observations of the Crab Nebula's Asymmetrical Development
Scowen, P. A.; Loll, A. M.; Desch, S. J. +1 more
We present the first Hubble Space Telescope Wide Field Planetary Camera-2 imaging survey of the entire Crab Nebula, in the filters F502N ([O III] emission), F673N ([S II]), F631N ([O I]), and F547M (continuum). We use our mosaics to characterize the pulsar wind nebula (PWN) and its three-dimensional structure, the ionizational structure in the fil…
Erratum: "An Estimate of the Chemical Composition of Titan's Lakes" (2009, ApJL, 707, L128)
Mousis, Olivier; Lunine, Jonathan I.; Lavvas, Panayotis +2 more
Lunar opposition effect as inferred from Chandrayaan-1 M3 data
Shkuratov, Yuriy; Kaydash, Vadym; Korokhin, Viktor +1 more
The shadow-hiding and coherent backscattering enhancement mechanisms are considered to be the major contributors to the brightness opposition effect of the Moon. However, the actual proportions of the mechanisms at different phase angles still remain not well determined. In order to assess the lunar phase function across small phase angles, we uti…
The Two-dimensional Projected Spatial Distribution of Globular Clusters. I. Method and Application to NGC 4261
Zezas, A.; Luo, B.; Fabbiano, G. +7 more
We present a new method for the determination of the two-dimensional (2D) projected spatial distribution of globular clusters (GCs) in external galaxies. This method is based on the K-Nearest Neighbor density estimator of Dressler, complemented by Monte-Carlo simulations to establish the statistical significance of the results. We apply this metho…
Observation of Flux-tube Crossings in the Solar Wind
Li, G.; Li, X.; Arnold, L. +1 more
Current sheets are ubiquitous in the solar wind. They are a major source of the solar wind MHD turbulence intermittency. They may result from nonlinear interactions of the solar wind MHD turbulence or are the boundaries of flux tubes that originate from the solar surface. Some current sheets appear in pairs and are the boundaries of transient stru…
The star formation history of the Sculptor dwarf irregular galaxy
Cole, A. A.; Lianou, S.
Aims: We study the resolved stellar populations and derive the star formation history of the Sculptor dwarf irregular galaxy (SDIG), a gas-rich dwarf galaxy member of the NGC 7793 subgroup in the Sculptor group of galaxies.
Methods: We constructed a colour - magnitude diagram (CMD) using archival observations from the Hubble Space Telesc…
Discovery of a Highly Variable Dipping Ultraluminous X-Ray Source in M94
Remillard, Ronald A.; Lin, Dacheng; Webb, Natalie A. +2 more
We report the discovery of a new ultraluminous X-ray source (ULX) 2XMM J125048.6+410743 within the spiral galaxy M94. The source has been observed by ROSAT, Chandra, and XMM-Newton on several occasions, exhibiting as a highly variable persistent source or a recurrent transient with a flux variation factor of gsim100, a high duty cycle (at least ~7…
G048.66-0.29: Physical State of an Isolated Site of Massive Star Formation
Henning, Th.; Krause, O.; Beuther, H. +9 more
We present continuum observations of the infrared dark cloud (IRDC) G48.66-0.22 (G48) obtained with Herschel, Spitzer, and APEX, in addition to several molecular line observations. The Herschel maps are used to derive temperature and column density maps of G48 using a model based on a modified blackbody. We find that G48 has a relatively simple st…
X-ray variability and energy spectra from NGC 5408 X-1 with XMM-Newton
Wolter, A.; Belloni, T. M.; Caballero-García, M. D.
The notion of source states characterizing the X-ray emission from black hole binaries has revealed to be a very useful tool to disentangle the complex spectral and aperiodic phenomenology displayed by those classes of accreting objects. We seek to use the same tools for ultraluminous X-ray (ULX) sources. We analysed the data from the longest obse…
Temporal Variations of X-Ray Solar Flare Loops: Length, Corpulence, Position, Temperature, Plasma Pressure, and Spectra
Kontar, Eduard P.; Jeffrey, Natasha L. S.
The spatial and spectral properties of three solar flare coronal X-ray loops are studied before, during, and after the peak X-ray emission. Using observations from the Ramaty High Energy Solar Spectroscopic Imager (RHESSI), we deduce the temporal changes in emitting X-ray length, corpulence, volume, position, number density, and thermal pressure. …