Search Publications
Optical monitoring of extragalactic sources for linking the ICRF and the future Gaia celestial reference frame. I. Variability of ICRF sources
Bouquillon, S.; Lambert, S.; Souchay, J. +8 more
Context. The astrometric mission Gaia of the European Space Agency is scheduled to be launched in 2013. It will provide an astrometric catalog of 500 000 extragalactic sources that could be the basis of a new optical reference frame after the Hipparcos satellite one. On the other hand, the current International Celestial Reference Frame (ICRF) is …
Venus nitric oxide nightglow mapping from SPICAV nadir observations
Bertaux, J. -L.; Gérard, J. -C.; Stiepen, A. +2 more
Nitric oxide δ (190-240 nm) and γ (255-270 nm) bands have been observed on the Venus nightside with Venus Express SPICAV instrument operated in the nadir mode. These ultraviolet emissions arise from the de-excitation of NO molecules created by radiative recombination of O(3P) and N(4S) atoms. These atoms are produced on the d…
A Deep Keck/NIRC2 Search for Thermal Emission from Planetary Companions Orbiting Fomalhaut
Currie, Thayne; Debes, John H.; Cloutier, Ryan +2 more
We present deep Keck/NIRC2 1.6 and 3.8 µm imaging of Fomalhaut to constrain the near-infrared brightness of Fomalhaut b, recently confirmed as a likely planet, and search for additional planets at r proj = 15-150 AU. Using advanced/novel point spread function subtraction techniques, we identify seven candidate substellar companion…
Cold fronts and metal anisotropies in the X-ray cool core of the galaxy cluster Zw 1742+3306
Gastaldello, F.; Ettori, S.; Gaspari, M. +5 more
Context. In recent years, our understanding of the cool cores of galaxy clusters has changed. Once thought to be relatively simple places where gas cools and flows towards the centre, now they are believed to be very dynamic places where heating from the central active galactic nucleus (AGN) and cooling, as inferred from active star formation, mol…
Multiscale studies of the three-dimensional dayside X-line
Hasegawa, H.; Fuselier, S. A.; Burch, J. L. +4 more
We review recent experience from the Cluster, Double Star, and THEMIS missions for lessons that apply to the upcoming Magnetospheric Multiscale Mission (MMS) being developed for launch in 2014. On global scales, simulation and statistical studies lead to mean configurations of dayside reconnection, implying specific relative alignments of the infl…
The evolution of the jet from Herbig Ae star HD 163296 from 1999 to 2011
Günther, H. M.; Schneider, P. C.; Li, Z. -Y.
Young A and B stars, the so-called Herbig Ae/Be stars (HAeBe), are surrounded by active accretion disks and drive outflows. We study the jet HH 409, which is launched from the HAeBe star HD 163296, using new and archival observations from Chandra and HST/STIS. In X-rays we can show that the central source is not significantly extended. The approac…
Young viscous flows in the Lowell crater of Orientale basin, Moon: Impact melts or volcanic eruptions?
Srivastava, N.; Kumar, D.; Gupta, R. P.
Topographical, morphological and spectral reflectance studies have been carried out for a distinct resurface event inside Copernican aged Lowell crater (13.00°S 103.40°W), Orientale basin, using high resolution TC, MI-VIS, LROC-NAC, and M3 data from Kaguya, Lunar Reconnaissance Orbiter (LRO) and Chandrayaan-1 missions. The resurfacing i…
Galaxy and Mass Assembly (GAMA): Witnessing the Assembly of the Cluster ABELL 1882
van Kampen, E.; Edge, A. C.; Hopkins, A. M. +14 more
We present a combined optical and X-ray analysis of the rich cluster ABELL 1882 (A1882) with the aim of identifying merging substructure and understanding the recent assembly history of this system. Our optical data consist of spectra drawn from the Galaxy and Mass Assembly survey, which lends itself to this kind of detailed study thanks to its de…
Dynamical Fragmentation of the T Pyxidis Nova Shell During Recurrent Eruptions
Zurek, David R.; Shara, Michael M.; Mac Low, Mordecai-Mark +1 more
Hubble Space Telescope images of the ejecta surrounding the nova T Pyxidis resolve the emission into more than 2000 bright knots. We simulate the dynamical evolution of the ejecta from T Pyxidis during its multiple eruptions over the last 150 years using the adaptive mesh refinement code Ramses. We demonstrate that the observed knots are the resul…
Saturn’s ring temperatures at equinox
Spilker, Linda; Ferrari, Cecile; Morishima, Ryuji
Modeling the thermal emission of Saturn’s rings is challenging due to the numerous heating sources as well as the structural properties of the disk and of the particles that are closely related. At equinox, however, rings are externally heated by Saturn alone and the problem is somewhat simplified. We test the abilities of our current models to re…