Search Publications

A model for the temperature-dependence of tidal dissipation in convective plumes on icy satellites: Implications for Europa and Enceladus

Showman, Adam P.; Mitri, Giuseppe

To explain the formation of surface features on Europa, Enceladus, and other satellites, many authors have postulated the spatial localization of tidal heating within convective plumes. However, the concept that enhanced tidal heating can occur within a convective plume has not been rigorously tested. Most models of this phenomenon adopt a tidal h…

An intense state of hard X-ray emission of Cyg X-1 observed by INTEGRAL coincident with TeV measurements

Malzac, J.; Laurent, P.; Cadolle Bel, M. +3 more

Aims: We present INTEGRAL light curves and spectra of the black-hole binary Cyg X-1 during a bright event that occurred in 2006 September, and which was simultaneous with a detection at 0.15-1 TeV energies by the MAGIC telescope.
Methods: We analyse the hard X-ray emission from 18 to 700 keV with the INTEGRAL data taken on 2006 September 24-26…

An intriguing solar microflare observed with RHESSI, Hinode, and TRACE

Krucker, S.; Lin, R. P.; Hannah, I. G. +2 more

Aims:We investigate particle acceleration and heating in a solar microflare.
Methods: In a microflare with non-thermal emission to remarkably high energies (>50 keV), we investigate the hard X-rays with RHESSI imaging and spectroscopy and the resulting thermal emission seen in soft X-rays with Hinode/XRT and in EUV with TRACE.
Results: …

The Shape of Cas A

Wheeler, J. Craig; Maund, Justyn R.; Couch, Sean M.

On the basis of optical, IR, and X-ray studies of Cas A, we propose a geometry for the remnant based on a "jet-induced" scenario with significant systematic departures from axial symmetry. In this model, the main jet axis is oriented in the direction of strong blueshifted motion at an angle of 110°-120° east of north and about 40°-50° to the east …

Spatial Distribution of Magnetic Reconnection in the 2006 December 13 Solar Flare as Observed by Hinode

Jing, Ju; Wang, Haimin; Chae, Jongchul

A massive two-ribbon flare and its source magnetic field region were well captured by the Solar Optical Telescope (SOT) on board Hinode in the Ca II H spectral line and by the Spectro-Polarimeter of SOT, respectively. Using the high-resolution Hinode data sets, we compare the spatial distribution of the local magnetic reconnection rate and the ene…

The properties of Titan's surface at the Huygens landing site from DISR observations

Keller, H. U.; Küppers, M.; Schröder, S. E. +3 more

The descent imager/spectral radiometer (DISR) onboard the Huygens probe investigated the radiation balance inside Titan's atmosphere and took hundreds of images and spectra of the ground during the descent. The scattering of the aerosols in the atmosphere and the absorption by methane strongly influence the irradiation reaching the surface and the…

Integral-field spectroscopy of a Lyman-break galaxy at z = 3.2: evidence for merging

Verma, A.; Davies, R. I.; Eisenhauer, F. +2 more

We present spatially-resolved, rest-frame optical spectroscopy of a z∼ 3 Lyman-break galaxy (LBG), Q0347-383 C5, obtained with SINFONI on the VLT. This galaxy, among the ∼ 10% brightest LBGs, is only the second z∼ 3 LBG observed with an integral-field spectrograph. It was first described by Pettini et al. (2001, ApJ, 554, 981), who obtained WFPC2 …

Heterogeneous solid/gas chemistry of organic compounds related to comets, meteorites, Titan, and Mars: Laboratory and in lower Earth orbit experiments

Szopa, C.; Cottin, H.; Coll, P. +14 more

To understand the evolution of organic molecules involved in extraterrestrial environments and with exobiological implications, many experimental programs in the laboratory are devoted to photochemical studies in the gaseous phase as well as in the solid state. The validity of such studies and their applications to extraterrestrial environments ca…

Suprathermal electron evolution in a Parker spiral magnetic field

Owens, M. J.; Crooker, N. U.; Schwadron, N. A.

Suprathermal electrons (>70 eV) form a small fraction of the total solar wind electron density but serve as valuable tracers of heliospheric magnetic field topology. Their usefulness as tracers of magnetic loops with both feet rooted on the Sun, however, most likely fades as the loops expand beyond some distance owing to scattering. As a first …

On the detection of the progenitor of the type Ia supernova 2007on

Bassa, Cees; Nelemans, Gijs; Voss, Rasmus +1 more

We present new Chandra X-ray observations and detailed astrometry of the field of the type Ia supernova 2007on, for which the detection of a likely progenitor in archival Chandra data was recently reported.

No source is detected in the new Chandra images, taken six weeks after optical maximum. We calculate a 90-99 per cent probability that an…