Search Publications
Disk-Jet Coupling in the Low-Mass X-Ray Binary 4U 1636-53 from INTEGRAL Observations
Ubertini, Pietro; Bazzano, Angela; Fiocchi, Mariateresa +1 more
We report on the spectral analysis of the neutron star (atoll-type) low-mass X-ray binary 4U 1636-53 as observed by the INTEGRAL and BeppoSAX satellites. The spectral behavior in three different epochs, corresponding to three different spectral states, has been investigated in depth. Spectra from two data sets show a continuum that is well describ…
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…
Latitudinal variation of Saturn photochemistry deduced from spatially-resolved ultraviolet spectra
Fouchet, Thierry; Connerney, J. E. P.; Prangé, Renée +2 more
We obtained spatially-resolved ultraviolet spectra of Saturn in 1994 with the Faint Object Spectrometer and Goddard High Resolution Spectrograph of the Hubble Space Telescope. We observed four areas on the planet at 15° N, 33° S, 41° S, and 52° S, with a field-of-view of less than 2 × 2 arcsec 2, compared to the 16-arcsec planet diamete…
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 …
Solar Energetic Particle Charge States: An Overview
Klecker, B.; Möbius, E.; Popecki, M. A.
The ionic charge distributions of solar energetic particles (SEP) as observed in interplanetary space provide fundamental information about the origin of these particles, and the acceleration and propagation processes at the Sun and in interplanetary space. In this paper we review the measurements of ionic charge states of energetic particles in i…
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…
X-ray observations of three young, early-type galaxies
Forbes, Duncan A.; Sansom, A. E.; O'Sullivan, E. +2 more
Massive haloes of hot plasma exist around some, but not all elliptical galaxies. There is evidence that this is related to the age of the galaxy. In this paper, new X-ray observations are presented for three early-type galaxies that show evidence of youth, in order to investigate their X-ray components and properties. NGC 5363 and NGC 2865 were fo…
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…