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Ultraviolet emissions from the magnetic footprints of Io, Ganymede and Europa on Jupiter
Clarke, J. T.; Waite, J. H.; Ballester, G. +8 more
Io leaves a magnetic footprint on Jupiter's upper atmosphere that appears as a spot of ultraviolet emission that remains fixed underneath Io as Jupiter rotates. The specific physical mechanisms responsible for generating those emissions are not well understood, but in general the spot seems to arise because of an electromagnetic interaction betwee…
Are the Narrow-Line Regions in Active Galaxies Dusty and Radiation Pressure Dominated?
Dopita, Michael A.; Sutherland, Ralph S.; Binette, Luc +2 more
The remarkable similarity between emission spectra of narrow-line regions (NLRs) in Seyfert galaxies has long presented a mystery. In photoionization models, this similarity implies that the ionization parameter is nearly always the same, about U~0.01. Here we present dusty, radiation pressure-dominated photoionization models that can provide natu…
The new emerging model for the structure of cooling cores in clusters of galaxies
Böhringer, H.; Churazov, E.; Chen, Y. +2 more
New X-ray observations with XMM-Newton show a lack of spectral evidence for large amounts of cooling and condensing gas in the centers of galaxy clusters believed to harbour strong cooling flows. This paper re-explores the cooling flow scenario in the light of the new observations. We explore the diagnostics of the temperature structure of cooling…
Time-Distance Helioseismology: The Forward Problem for Random Distributed Sources
Birch, A. C.; Gizon, L.
The forward problem of time-distance helioseismology is computing travel-time perturbations that result from perturbations to a solar model. We present a new and physically motivated general framework for calculations of the sensitivity of travel times to small local perturbations to solar properties, taking into account the fact that the sources …
Helioseismic Measurement of Solar Torsional Oscillations
Thompson, M. J.; Christensen-Dalsgaard, J.; Schou, J. +2 more
Bands of slower and faster rotation, the so-called torsional oscillations, are observed at the Sun's surface to migrate in latitude over the 11-year solar cycle. Here, we report on the temporal variations of the Sun's internal rotation from solar p-mode frequencies obtained over nearly 6 years by the Michelson Doppler Imager (MDI) instrument on bo…
The mass profile of A1413 observed with XMM-Newton: Implications for the M-T relation
Arnaud, M.; Pratt, G. W.
We present an XMM-Newton et al. observation of A1413, a hot (kT = 6.5 kev ) galaxy cluster at z=0.143. We construct gas and temperature profiles over the radial range up to ~ 1700 kpc. This radius corresponds to a density contrast delta ~ 500 with respect to the critical density at the redshift of the cluster, or equivalently ~ 0.7 r200…
Evidence of Spin and Energy Extraction in a Galactic Black Hole Candidate: The XMM-Newton/EPIC-pn Spectrum of XTE J1650-500
Wijnands, R.; Fabian, A. C.; Miller, J. M. +7 more
We observed the Galactic black hole candidate XTE J1650-500 early in its fall of 2001 outburst with the XMM-Newton European Photon Imaging pn Camera (EPIC-pn). The observed spectrum is consistent with the source having been in the ``very high'' state. We find a broad, skewed Fe Kα emission line that suggests the primary in this system may be a Ker…
Deviations from the Local Hubble Flow. I. The Tip of the Red Giant Branch as a Distance Indicator
Méndez, Bryan; Davis, Marc; Moustakas, John +3 more
The properties of the velocity field in the local volume (cz<550 km s-1) have been difficult to constrain because of a lack of a consistent set of galaxy distances. The sparse observations available to date suggest a remarkably quiet flow, with little deviation from a pure Hubble law. However, velocity field models based on the distr…
Detection of a Supernova Signature Associated with GRB 011121
Piro, L.; Axelrod, T. S.; Frontera, F. +20 more
Using observations from an extensive monitoring campaign with the Hubble Space Telescope, we present the detection of an intermediate-time flux excess that is redder in color relative to the afterglow of GRB 011121, currently distinguished as the gamma-ray burst with the lowest known redshift. The red ``bump,'' which exhibits a spectral rollover a…
Crystalline silicate dust around evolved stars. II. The crystalline silicate complexes
Waters, L. B. F. M.; Tielens, A. G. G. M.; Molster, F. J.
This is the second paper in a series of three in which we present an exhaustive inventory of the solid state emission bands observed in a sample of 17 oxygen-rich dust shells surrounding evolved stars. The data were taken with the Short and Long Wavelength Spectrographs on board of the Infrared Space Observatory (ISO) and cover the 2 to 200 mu m w…