Search Publications
Radial Speed Evolution of Interplanetary Coronal Mass Ejections During Solar Cycle 23
Tokumaru, M.; Fujiki, K.; Iju, T.
We report radial-speed evolution of interplanetary coronal mass ejections (ICMEs) detected by the Large Angle and Spectrometric Coronagraph onboard the Solar and Heliospheric Observatory (SOHO/LASCO), interplanetary scintillation (IPS) at 327 MHz, and in-situ observations. We analyze solar-wind disturbance factor (g-value) data derived from IPS ob…
The dynamics of the plasmasphere: Recent results
De Keyser, J.; Darrouzet, F.
The purpose of this paper is to review recent advances in the study of the Earth's plasmasphere. Most of these have been obtained with data from two missions launched in 2000, Cluster and IMAGE. Indeed, those missions have deeply modified our understanding of this region due to their specificity: Cluster is a 4-spacecraft mission and IMAGE a globa…
Multi-wavelength Studies of Spectacular Ram Pressure Stripping of a Galaxy: Discovery of an X-Ray Absorption Feature
Makishima, Kazuo; Nakazawa, Kazuhiro; Gu, Liyi +5 more
We report the detection of an X-ray absorption feature near the galaxy M86 in the Virgo cluster. The absorber has a column density of 2-3 × 1020 cm-2, and its position coincides with the peak of an intracluster H I cloud which was removed from the galaxy NGC 4388 presumably by ram pressure. These results indicate that the H I…
Kinematics of the Orion Trapezium Based on Diffracto-Astrometry and Historical Data
Olivares, J.; Sánchez, L. J.; Ruelas-Mayorga, A. +3 more
Using the novel Diffracto-Astrometry technique, we analyze 44 Hubble Space Telescope Wide Field Planetary Camera 2 images of the Orion Trapezium (OT) taken over a span of 12 yr (1995-2007). We measure the relative positions of the six brighter OT components (A-F) and supplement these results with measurements of the relative separations and positi…
The Local Environment of Ultraluminous X-Ray Sources Viewed by XMM-Newton's Optical Monitor
Berghea, C. T.; Dudik, R. P.; Winter, L. M. +1 more
We have used XMM-Newton's Optical Monitor (OM) images to study the local environment of a sample of 27 ultraluminous X-ray sources (ULXs) in nearby galaxies. UVW1 fluxes were extracted from 100 pc regions centered on the ULX positions. We find that at least 4 ULXs (out of 10 published) have spectral types that are consistent with previous literatu…
Polarimetric studies of comet C/2009 P1 (Garradd)
Wolf, S.; Medhi, B. J.; Das, H. S. +3 more
We present the optical imaging polarimetric observations of comet C/2009 P1 (Garradd) at three different phase angles e.g. 28.2°, 28.1° and 21.6°. The observations were carried out using the Inter University Centre for Astronomy and Astrophysics (IUCAA) Faint Object Spectrograph and Camera mounted on Cassegrain focus of the 2 m telescope of IGO, I…
Astronomical image denoising using dictionary learning
Starck, J. L.; Beckouche, S.; Fadili, J.
Astronomical images suffer a constant presence of multiple defects that are consequences of the atmospheric conditions and of the intrinsic properties of the acquisition equipment. One of the most frequent defects in astronomical imaging is the presence of additive noise which makes a denoising step mandatory before processing data. During the las…
The planetary nebulae population in the nuclear regions of M31: the SAURON view
Bacon, Roland; Emsellem, Eric; Sarzi, Marc +5 more
The study of extragalactic planetary nebulae (PNe) in the optical regions of galaxies, where the properties of their stellar population can be best characterized, is a promising ground to better understand the late evolution of stars across different galactic environments. Following a first study of the central regions of M32 that illustrated the …
Modeling the effect of atmospheric gravity waves on Saturn's ionosphere
Matcheva, Katia I.; Barrow, Daniel J.
Cassini's radio occultations by Saturn reveal a highly variable ionosphere with a complex vertical structure often dominated by several sharp layers of electrons. The cause of these layers has not yet been satisfactorily explained. This paper demonstrates that the observed system of layers in Saturn's lower ionosphere can be explained by the prese…
Characterization of middle-atmosphere polar warming at Mars
Forget, F.; Smith, M.; Bougher, S. +3 more
We characterize middle-atmosphere polar warming (PW) using nearly three Martian years of temperature observations by the Mars Climate Sounder. We report the observed structure of PW and share hypotheses as to possible explanations, which have yet to be tested with global dynamical models. In the data, PW manifested between p = 15 Pa and p = 4.8×10…