Search Publications
The change of solar shape in time and depth. Some consequences for space climate
Kosovichev, A. G.; Lefebvre, S.; Rozelot, J. P.
During the last five years, studies of the Sun and Sun-Earth relationships have dramatically changed our view on solar terrestrial physics. We will here focus on new views on the solar interior. The internal non-homogeneous mass distribution and non-uniform angular velocity (function of the radial distance to the center and of the latitude) yield …
Carbon isotopic enrichment in Titan's tholins? Implications for Titan's aerosols
Szopa, C.; Coll, P.; Raulin, F. +5 more
Since the discovery of the main composition of Titan's atmosphere, many laboratory experiments have been carried out to reproduce its chemical evolution, particularly the formation of organic haze particles found throughout this atmosphere. Some of these simulations have produced solid products - referred to as Titan's tholins - that are assumed t…
Revisiting the Soft X-Ray Excess Emission in Clusters of Galaxies Observed with XMM-Newton
Kaastra, J.; Bonamente, M.; Nevalainen, J.
We analyze XMM-Newton galaxy clusters Abell 1795, Abell S1101, Abell 1835, and MKW 3s in order to test whether their soft X-ray excess emission in the 0.2-0.5 keV band as reported by Kaastra et al. maintains after application of current knowledge of the XMM-Newton background and calibration. In this context, we examine the claim (Bregman & Llo…
Low-frequency waves in the foreshock of Saturn: First results from Cassini
Dougherty, M. K.; Hospodarsky, G. B.; Thomsen, M. +4 more
We present the first characterization of low-frequency upstream waves associated with Saturn's foreshock from observations by the Cassini spacecraft. A classification based on their frequency in the spacecraft frame (s/c) yields two groups: (1) a large majority of waves with frequencies below the local proton cyclotron frequency ΩH+ and…
Multiscale optical flow probing of dynamics in solar EUV images. Algorithm, calibration, and first results
Hochedez, J. -F.; Gissot, S. F.
Context: Movies of the solar atmosphere reveal motion and variations in brightness. In particular, sequences of coronal images exhibit the plane-of-the-sky component of the velocity combined with other variations in the signal. The present work analyses solar extreme-ultraviolet images, as recorded by the Extreme ultraviolet Imaging Telescope (EIT…
A Multiwavelength Study of 1WGA J1346.5-6255: A New γ Cas Analog Unrelated to the Background Supernova Remnant G309.2-00.6
Safi-Harb, Samar; Lu, Fangjun; Chen, Yong +5 more
1WGA J1346.5-6255 is a ROSAT X-ray source found within the radio lobes of the supernova remnant (SNR) G309.2-00.6. It appears to coincide with the bright and early-type star HD 119682, in the galactic open cluster NGC 5281. Its radio morphology, consisting of two brightened and distorted arcs of emission on opposite sides of the 1WGA J1346.5-6255 …
Predictions of the electrical conductivity and charging of the aerosols in Titan's nighttime atmosphere
Tripathi, S.; Whitten, R. C.; Borucki, W. J.
The electrical conductivity and electrical charge on Titan's atmosphere are computed for altitudes between 0 and 400 km on the nightside for which the main source of ionization is galactic cosmic rays (GCR). Unlike the dayside, electrical charging of the aerosol particles at night is not only negative but also time-dependent. Hence a time-dependen…
The use of genetic algorithms to model protoplanetary discs
Hetem, Annibal; Gregorio-Hetem, Jane
The protoplanetary discs of T Tauri and Herbig Ae/Be stars have previously been studied using geometric disc models to fit their spectral energy distribution (SED). The simulations provide a means to reproduce the signatures of various circumstellar structures, which are related to different levels of infrared excess. With the aim of improving our…
Statistics of superimposed flares in the Taurus molecular cloud
Audard, M.; Güdel, M.; Telleschi, A. +2 more
Context: Stochastically occurring flares provide a possible mechanism of coronal heating in magnetically active stars such as T Tauri objects in star-forming regions.
Aims: We investigate the statistics of stellar X-ray light curves from the XMM-Newton Extended Survey of the Taurus Molecular Cloud (XEST).
Methods: To this end, the light cu…
Study of the fast X-ray transient XTE J1901+014 based on INTEGRAL, RXTE, and ROSAT data
Lutovinov, A. A.; Karasev, D. I.; Grebenev, S. A.
The source XTE J1901+014 discovered by the RXTE observatory during an intense outburst of hard radiation and classified as a fast X-ray transient is studied. The source’s spectral characteristics in the quiescent state have been investigated for the first time both in the soft X-ray energy range (3 20 keV) based on ROSAT and RXTE data and in the h…