Search Publications
Concatenation of HRSC colour and OMEGA data for the determination and 3D-parameterization of high-altitude CO 2 clouds in the Martian atmosphere
Montmessin, Franck; Gondet, Brigitte; Hoffmann, Harald +3 more
We used Mars Express HRSC and OMEGA data to investigate mesospheric cloud features observed in the equatorial belt of Mars from December 2007 until early March 2008. This period corresponds to early northern spring of Martian year 29. The reflection peak at 4.26 µm in OMEGA data identifies the clouds as CO 2 ice clouds. HRSC obser…
Comparison of a Global Magnetic Evolution Model with Observations of Coronal Mass Ejections
van Ballegooijen, A. A.; Nandy, Dibyendu; Yeates, A. R. +3 more
The relative importance of different initiation mechanisms for coronal mass ejections (CMEs) on the Sun is uncertain. One possible mechanism is the loss of equilibrium of coronal magnetic flux ropes formed gradually by large-scale surface motions. In this paper, the locations of flux rope ejections in a recently developed quasi-static global evolu…
Granular-scale Magnetic Flux Cancellations in the Photosphere
Kubo, M.; Lites, B. W.; Low, B. C.
We investigate the evolution of five granular-scale magnetic flux cancellations just outside the moat region of a sunspot by using accurate spectropolarimetric measurements and G-band images with the Solar Optical Telescope (SOT) aboard Hinode. The opposite-polarity magnetic elements approach a junction of the intergranular lanes and then collide …
Results from DROXO. III. Observation, source list, and X-ray properties of sources detected in the ``Deep Rho Ophiuchi XMM-Newton Observation''
Testi, L.; Grosso, N.; Micela, G. +8 more
Context. X-rays from very young stars are powerful probes to investigate the mechanisms at work in the very first stages of the star formation and the origin of X-ray emission in very young stars.
Aims: We present results from a 500 ks long observation of the Rho Ophiuchi cloud with a XMM-Newton large program named DROXO, aiming at studying t…
Metal abundances in the hottest known DO white dwarf (KPD 0005+5106)
Rauch, T.; Werner, K.; Kruk, J. W. +1 more
We present the analysis of ultraviolet and optical spectra of KPD 0005+5106. Redetermination of the atmospheric parameters is necessary because the recent discovery of highly ionised metals (Ne VIII, Ca X) indicates that the effective temperature is significantly higher than previously thought. Here we announce the discovery of lines from highly i…
Origin(s) of the Highly Ionized High-Velocity Clouds Based on Their Distances
Lehner, N.; Howk, J. C.
Previous Hubble Space Telescope and FUSE observations have revealed highly ionized high-velocity clouds (HVCs) or more generally low H I column HVCs along extragalactic sight lines over 70%-90% of the sky. The distances of these HVCs have remained largely unknown hindering from distinguishing a "Galactic" origin (e.g., outflow, inflow) from a "Loc…
Wide-field HST/ACS images of M81: the population of compact star clusters
Mayya, Y. D.; Rosa-González, D.; Santiago-Cortés, M.
We study the population of compact star clusters (CSCs) in M81, using the Hubble Space Telescope/Advanced Camera for Surveys (ACS) images in the filters F435W, F606W and F814W covering, for the first time, the entire optical extent of the galaxy. Our sample contains 435 clusters of full width at half-maximum less than 10 ACS pixels (9pc). The samp…
X-ray imaging of the ionisation cones in NGC 5252
Bianchi, S.; Cappi, M.; Guainazzi, M. +4 more
Context. The physical conditions of the gas forming the narrow-line regions (NLR) in active galactic nuclei (AGN) have been extensively studied in the optical band. Recently detailed X-ray studies have shown how the emission in the 0.1-2 keV band detected in Seyfert 2 galaxies is associated to gas lying close to or associated with the NLR.
Ai…
Evidence of Solar Flare Triggering Due to Loop-loop Interaction Caused by Footpoint Shear Motion
Srivastava, A. K.; Erdélyi, R.; Kumar, Pankaj +3 more
We analyze multi-wavelength data of an M7.9/1N class solar flare which occurred on 2006 April 27 in AR NOAA 10875. GOES soft X-ray images provide the most likely signature of two interacting loops and their reconnection, which triggers the solar flare. TRACE 195 Å images also reveal the loop-loop interaction and the formation of "X" points with co…
A Statistical Study of the Post-impulsive-phase Acceleration of Flare-associated Coronal Mass Ejections
Cheng, X.; Ding, M. D.; Zhang, J. +1 more
It is now generally accepted that the impulsive acceleration of a coronal mass ejection (CME) in the inner corona is closely correlated in time with the main energy release of the associated solar flare. In this paper, we examine in detail the post-impulsive-phase acceleration of a CME in the outer corona, which is the phase of evolution immediate…