Search Publications
Lens-Aided Multi-Angle Spectroscopy (LAMAS) Reveals Small-Scale Outflow Structure in Quasars
Green, Paul J.
Spectral differences between lensed quasar image components are common. Since lensing is intrinsically achromatic, these differences are typically explained as the effect of either microlensing, or as light path time delays sampling intrinsic quasar spectral variability. Here we advance a novel third hypothesis: some spectral differences are due t…
Analysis of Solar Flare Ribbon Evolution: A Semiautomated Approach
Tarbell, T. D.; Gaeng, T.; Saba, J. L. R.
We exploit a rare joint set of high-resolution, very high cadence TRACE UV images and high-resolution magnetograms from SOHO MDI to investigate the dynamical properties of flare ribbons in a GOES M1 class flare from NOAA active region 9236 on 2000 November 23 at 23:28 UT. Assuming that flare ribbons locate the chromospheric footpoints of magnetic …
Analysis of the Velocity Field of CMEs Using Optical Flow Methods
Vourlidas, Angelos; Colaninno, Robin C.
Optical flow is a powerful image processing tool for measuring motion in digital images. The optical flow algorithm provides an estimate of the velocity vector at every pixel from a pair of successive images. Here we present an application of this method to images of coronal mass ejections (CMEs). The technique is first tested and validated on a s…
A Puzzling Merger in A3266: The Hydrodynamic Picture from XMM-Newton
Finoguenov, A.; Jones, C.; Miniati, F. +2 more
Using a mosaic of nine XMM-Newton observations, we study the hydrodynamic state of the merging cluster of galaxies Abell 3266. The high signal-to-noise ratio of spectroscopic data of XMM-Newton allows us to determine the thermodynamic conditions of the intracluster medium on ~50 kpc scales. High statistical quality X-ray data reveal the presence o…
A Population of Binaries in the Asymptotic Giant Branch of 47 Tucanae?
Ferraro, Francesco R.; Lanzoni, Barbara; Beccari, Giacomo +1 more
We have used a set of archived Hubble Space Telescope Advanced Camera for Surveys images to probe the evolved populations of the globular cluster 47 Tucanae. We find an excess of asymptotic giant branch (AGB) stars in the cluster core. We interpret this feature as the signature of an extrapopulation likely made by the progeny of massive stars orig…
Hubble Space Telescope Observations of Oxygen-rich Supernova Remnants in the Magellanic Clouds. III. WFPC2 Imaging of the Young, Crab-like Supernova Remnant SNR 0540-69.3
Blair, William P.; Smith, Nathan; Kirshner, Robert P. +3 more
HST images with WFPC2 of the young, oxygen-rich, Crab-like supernova remnant SNR 0540-69.3 in the Large Magellanic Cloud (LMC) reveal details of the emission distribution and the relationship between the expanding ejecta and synchrotron nebula. The emission distributions appear very similar to those seen in the Crab Nebula, with the ejecta located…
Chandra and XMM-Newton Observations of the Vela-like Pulsar B1046-58
Gaensler, B. M.; Gonzalez, M. E.; Kaspi, V. M. +1 more
We present results from Chandra and XMM-Newton observations of the radio pulsar B1046-58. A high-resolution spatial analysis reveals an asymmetric pulsar wind nebula (PWN), ~6''×11'' in size. The combined emission from the pulsar and its PWN is faint, with a best-fit power-law photon index of Γ=1.7+0.4-0.2
The Unusual X-Ray Spectrum of FU Orionis
Skinner, Stephen L.; Güdel, Manuel; Briggs, Kevin R.
FU Orionis objects (FUors) have undergone strong optical outbursts and are thought to be young low-mass stars accreting at high rates of up to M˙acc~10-4 Msolar yr-1. FUors have been extensively studied at optical and infrared wavelengths, but little is known about their X-ray properties. We have thus in…
Proper-Motion Measurements of the Cygnus Egg Nebula
Ueta, Toshiya; Meixner, Margaret; Murakawa, Koji
We present the results of proper-motion measurements of the dust shell structure in the Egg Nebula (AFGL 2688, CRL 2688, V1610 Cyg), based on the archived two-epoch data at 2 µm taken with the Hubble Space Telescope. We measured the amount of motion of local structures in the nebula by determining their relative shifts over an interval of 5.…
Swift XRT Follow-up Observations of TeV Sources of the HESS Inner Galaxy Survey
Masetti, N.; Bird, A. J.; Ubertini, P. +6 more
In order to provide a firm identification of the newly discovered Galactic TeV sources, a search for counterparts in a broad band from soft X-ray to soft gamma rays is crucial as data in these wave bands allow us to distinguish between different types of suggested models (for example, leptonic vs. hadronic) and, in turn, to disentangle their natur…