Search Publications
Exceptional H2 emission in the Antennae galaxies: Pre-starburst shocks from the galaxy collision
Klaas, U.; Haas, M.; Chini, R.
The collision of gas-rich galaxies is believed to produce strong shocks between their gas clouds which cause the onset of the observed bursts of extended star formation. However, the so far observed shock signatures in colliding galaxies can be explained essentially by winds from already existing massive stars and supernovae and thus do not give a…
Hubble Space Telescope and United Kingdom Infrared Telescope Observations of the Center of the Trifid Nebula: Evidence for the Photoevaporation of a Proplyd and a Protostellar Condensation
Geballe, T. R.; Yusef-Zadeh, F.; Biretta, J.
The Trifid Nebula (M20) is a well-known prominent optical H II region trisected by bands of obscuring dust lanes and excited by an O7.5 star, HD 164492A. Previous near-IR, mid-IR, and radio continuum observations of the cluster of stars at the center of the Trifid Nebula indicated the presence of circumstellar disks associated with hot stars with …
X-ray properties of NGC 300. I. Global properties of X-ray point sources and their optical counterparts
Schirmer, M.; Wilms, J.; Kendziorra, E. +1 more
We present X-ray properties of NGC 300 point sources, extracted from 66 ks of XMM-Newton data taken in 2000 December and 2001 January. A total of 163 sources were detected in the energy range of 0.3-6 keV. We report on the global properties of the sources detected inside the D25 optical disk, such as the hardness ratio and X-ray fluxes,…
A possible line-like emission feature at 8 keV in the Seyfert 1.2 UGC 3973
Pietsch, W.; Fabian, A. C.; Boller, Th. +1 more
Two short X-ray exposures (<3600 s each) of the radio-quiet Seyfert 1.2 galaxy UGC 3973 (Mrk 79) were conducted with XMM-Newton as part of an active galactic nucleus snapshot survey. In this paper we concentrate on the significance and possible origin of a narrow 8-keV (rest frame) line-like emission feature detected with the pn instrument duri…
Hybrid simulation of ion cyclotron resonance in the solar wind: Evolution of velocity distribution functions
Li, Xing; Habbal, Shadia R.
Resonant interaction between ions (oxygen ions O+5 and protons) and ion cyclotron waves is investigated using a one dimensional hybrid code. Ion cyclotron waves are self-consistently generated by an ion cyclotron anisotropy instability. We focus on the detailed acceleration process of ions. The energization of oxygen ions due to waves i…
Ion-Pressure Equations Derived from Measurements in Space
Stasiewicz, K.
Cluster measurements at the bow shock, the magnetosheath, and the magnetospheric boundary layer are used to derive ion-pressure equations for hot anisotropic plasmas. It is demonstrated that both perpendicular and parallel ion pressures are well approximated by polybaric expressions ∝NγBκ, where N is the plasma density, B is …
S/2004 S 5: A new co-orbital companion for Dione
Cooper, N. J.; Murray, C. D.; Evans, M. W. +1 more
We describe the astrometry and dynamics of S/2004 S 5 (provisionally named Polydeuces), a new satellite of Saturn, discovered in images recorded using the Imaging Science Subsystem (ISS) of the Cassini spacecraft. A total of 119 observations are presented, 101 of which were obtained with Cassini's narrow-angle camera and 18 using the wide-angle ca…
Determination of stellar shape in microlensing event MOA 2002-BLG-33
Bennett, D. P.; Cook, K. H.; Gal-Yam, A. +30 more
We report a measurement of the shape of the source star in microlensing event MOA 2002-BLG-33. The lens for this event was a close binary whose centre-of-mass passed almost directly in front of the source star. At this time, the source star was closely bounded on all sides by a caustic of the lens. This allowed the oblateness of the source star to…
Exo-Astrobiological Aspects of Europa and Titan: From Observations to Speculations
Raulin, François
By extrapolating what we know on the origins of life on Earth, and in particular on the chemical processes which gave rise to the first living system, Europa and Titan appear as two major targets for studies of exo/astrobiology in the outer solar system. With the likely presence of water oceans relatively close to its surface, coupled to possible …
XMM-Newton observation of the long-period polar V1309 Orionis: the case for pure blobby accretion
Burwitz, V.; Beuermann, K.; Schwarz, R. +1 more
Using XMM-Newton we have obtained the first continuous X-ray observation covering a complete orbit of the longest period polar, V1309 Ori. The X-ray light curve is dominated by a short, bright phase interval with EPIC pn count rates reaching up to 15 cts s-1 per 30 s resolution bin. The bright phase emission is well described by a singl…