Search Publications
A Catastrophic Flux Rope in a Quadrupole Magnetic Field for Coronal Mass Ejections
Wang, J. -X.; Zhang, Y. -Z.
We propose a flux-rope model for the initiation of flare-associated CMEs. The model triggers the eruption with a catastrophic loss of MHD equilibrium and then requires magnetic reconnection to sustain the eruption's acceleration. We carry out 2.5-dimensional time-dependent resistive MHD simulations, choosing the initial state such that a flux rope…
The Frequency of Mid-Infrared Excess Sources in Galactic Surveys
Indebetouw, R.; Benjamin, R. A.; Wolfire, M. G. +27 more
We have identified 230 Tycho-2 Spectral Catalog stars that exhibit 8 µm mid-IR extraphotospheric excesses in the MSX and Spitzer GLIMPSE surveys. Of these, 183 are either OB stars earlier than B8 in which the excess plausibly arises from a thermal bremsstrahlung component or evolved stars in which the excess may be explained by an atmospheri…
Topographic and morphologic characteristics of Reull Vallis, Mars: Implications for the history of the Reull Vallis fluvial system
Neukum, G.; Ivanov, M. A.; Kostama, V. -P. +4 more
The eastern rim region of Hellas basin is characterized by the four prominent and quite extensively researched (cf. Crown et al., 2005, and references therein) outflow channels. In this work we focus on the Reull Vallis. On the basis of observations from available data sets, we present a hypothesis for the evolution of Reull Vallis and its complim…
Constraining the surface properties of Saturn's icy moons, using Cassini/CIRS emissivity spectra
Carvano, J. M.; Barucci, A.; Migliorini, A. +2 more
We have conducted a search for emissivity features in the thermal infrared spectrum of the icy satellites of Saturn, Phoebe, Iapetus, Enceladus, Tethys, and Hyperion, observed by the Composite Infrared Spectrometer (CIRS) on board the Cassini spacecraft. Despite the heterogeneity of the composition of these bodies depicted by Earth-based and Cassi…
Discovery of X-ray emission from the young radio pulsar PSR J1357-6429
Tiengo, A.; de Luca, A.; Esposito, P. +1 more
We present the first X-ray detection of the very young pulsar PSR J1357-6429 (characteristic age of 7.3 kyr) using data from the XMM-Newton and Chandra satellites. We find that the spectrum is well described by a power-law plus blackbody model, with photon index Γ=1.4 and blackbody temperature k_BT=160 eV. For the estimated distance of 2.5 kpc, th…
An overview of Jovian electrons during the distant Ulysses Jupiter flyby
Dalla, S.; Kunow, H.; Wibberenz, G. +9 more
Since the 1970's interplanetary electrons in the MeV energy range, of Jovian origin, have been extensively studied from close to the Sun to beyond the Kronian orbit, near the ecliptic. The Ulysses trajectory allowed to study the propagation of these particles, in a wide range of heliographic latitudes. The location of Jupiter with respect to the s…
Discovery of variable X-ray absorption in the cTTS AA Tauri
Schmitt, J. H. M. M.; Robrade, J.
We present XMM-Newton X-ray and UV observations of the classical T Tauri star AA Tau covering almost two rotational periods where P_rot ∼ 8.5 days. Clear, but uncorrelated variability is found at both wavebands. The variability observed at ~2100 Å follows the previously known optical period. Spectral analysis of the X-ray data results in significa…
X-ray flares on the UV Ceti-type star CC Eridani: a ``peculiar'' time-evolution of spectral parameters
Micela, G.; Reale, F.; Pillitteri, I. +3 more
Context: Weak flares are supposed to be an important heating agent of the outer layers of stellar atmospheres. However, due to instrumental limitations, only large X-ray flares have been studied in detail until now.
Aims: We used an XMM-Newton observation of the very active BY-Dra type binary star CC Eri in order to investigate the properties …
Circumnuclear Star Clusters in the Galaxy Merger NGC 6240, Observed with Keck Adaptive Optics and the Hubble Space Telescope
Schneider, G.; Max, C. E.; Pollack, L. K.
We discuss images of the central ~10 kpc (in projection) of the galaxy merger NGC 6240 at H and K' bands, taken with the NIRC2 narrow camera on Keck II using natural guide star adaptive optics. We detect 28 star clusters in the NIRC2 images, of which only 7 can be seen in the similar spatial resolution, archival WFPC2 Planetary Camera data at eith…
Silicates in D-Type Symbiotic Stars: An Infrared Space Observatory Overview
Ciroi, S.; Rafanelli, P.; Angeloni, R. +1 more
We investigate the IR spectral features of a sample of D-type symbiotic stars in order to constrain the emitting properties of coupled dust-gas particles across the whole system. In particular, by analyzing unexploited ISO Short Wavelength Spectrometer data, deriving the basic observational parameters of dust bands, and comparing them with respect…