Search Publications
Numerical Modeling of the Initiation of Coronal Mass Ejections in Active Region NOAA 9415
Poedts, S.; Zuccarello, F. P.; Meliani, Z.
Coronal mass ejections (CMEs) and solar flares are the main drivers of weather in space. Understanding how these events occur and what conditions might lead to eruptive events is of crucial importance for up to date and reliable space weather forecasting. The aim of this paper is to present a numerical magnetohydrodynamic (MHD) data-inspired model…
A statistical study of the cross-shock electric potential at low Mach number, quasi-perpendicular bow shock crossings using Cluster data
Bale, S. D.; Walker, S. N.; Balikhin, M. A. +3 more
The cross-shock electrostatic potential at the front of collision-less shocks plays a key role in the distribution of energy at the shock front. Multipoint measurements such as those provided by the Cluster II mission provide an ideal framework for the study of the cross-shock potential because of their ability to distinguish between temporal and …
Spatially resolved colours and stellar population properties in early-type galaxies at z ∼ 1.5
Longhetti, M.; Gargiulo, A.; Saracco, P. +2 more
We present F850LP - F160W colour gradients for 11 early-type galaxies (ETGs) at 1.0 < zspec < 1.9 selected from the GOODS-South field. Significant negative F850LP - F160W colour gradients (core redder than the outskirts) have been detected in ∼70 per cent of our sample within the effective radius Re, the remaining 30 pe…
Three-Dimensional Properties of Coronal Mass Ejections from STEREO/SECCHI Observations
Davies, J. A.; Bothmer, V.; Howard, R. A. +3 more
We identify 565 coronal mass ejections (CMEs) between January 2007 and December 2010 in observations from the twin STEREO/SECCHI/COR2 coronagraphs aboard the STEREO mission. Our list is in full agreement with the corresponding SOHO/LASCO CME Catalog (http://cdaw.gsfc.nasa.gov/CME_list/) for events with angular widths of 45∘ and up. The …
Study of Single-lobed Circular Polarization Profiles in the Quiet Sun
Sainz Dalda, A.; Martínez-Sykora, J.; Title, A. +1 more
The existence of asymmetries in the circular polarization (Stokes V) profiles emerging from the solar photosphere has been known since the 1970s. These profiles require the presence of a velocity gradient along the line of sight (LOS), possibly associated with gradients of magnetic field strength, inclination, and/or azimuth. We have focused our s…
Searching for heavily obscured post-AGB stars and planetary nebulae. II. Near-IR observations of IRAS sources
Guerrero, M. A.; Ramos-Larios, G.; Gómez, J. F. +2 more
The most massive AGB stars are expected to result in heavily obscured post-AGB stars, proto-PNe and PNe with highly axisymmetric morphologies. To investigate this evolutionary connection, we have selected a sample of 165 presumably obscured IRAS post-AGB star and PN candidates and obtained near-IR JHK images for 164 of them. These images, in conju…
HST/COS Observations of Thirteen New He II Quasars
Anderson, Scott F.; Schneider, Donald P.; York, Donald G. +3 more
The full reionization of intergalactic helium was a major event in the history of the intergalactic medium (IGM), and UV observations of the He II Gunn-Peterson trough allow us to characterize the end of this process at z ~ 3. Due to intervening hydrogen absorption, quasars allowing such study are rare, with only 33 known in the literature, and mo…
Deep Chandra and XMM-Newton X-ray observations of AWM 7 - I. Investigating X-ray surface brightness fluctuations
Fabian, A. C.; Sanders, J. S.
We investigate the levels of small-scale structure in surface brightness images of the core of the X-ray bright cool-core galaxy cluster AWM 7. After subtraction of a model of the smooth cluster emission, we find a number of approximately radial surface brightness depressions which are not present in simulated images and are seen in both the Chand…
Oscillations in Active Region Fan Loops: Observations from EIS/ Hinode and AIA/SDO
Banerjee, D.; Krishna Prasad, S.; Singh, Jagdev
Active region fan loops in AR 11076 were studied, in search of oscillations, using high cadence spectroscopic observations from Extreme-ultraviolet Imaging Spectrometer (EIS) on board Hinode combined with imaging sequences from the Atmospheric Imaging Assembly (AIA) on board Solar Dynamics Observatory (SDO). Spectra from EIS were analyzed in two s…
Quasi full-disk maps of solar horizontal velocities using SDO/HMI data
Roudier, Th.; Malherbe, J. M.; Gizon, L. +6 more
Aims: For the first time, the motion of granules (solar plasma on the surface on scales larger than 2.5 Mm) has been followed over the entire visible surface of the Sun, using SDO/HMI white-light data.
Methods: Horizontal velocity fields are derived from image correlation tracking using a new version of the coherent structure tracking al…