Search Publications
An optical/NIR survey of globular clusters in early-type galaxies. I. Introduction and data reduction procedures
Larsen, S. S.; Kuntschner, H.; Chies-Santos, A. L. +3 more
Context. The combination of optical and near-infrared (NIR) colours has the potential to break the age/metallicity degeneracy and offers a better metallicity sensitivity than optical colours alone. Previous tudies of extragalactic globular clusters (GCs) with this colour combination, however, have suffered from small samples or have been restricte…
Thermal properties of the asteroid (2867) Steins as observed by VIRTIS/Rosetta
Erard, S.; Drossart, P.; Capaccioni, F. +6 more
Context. To investigate thermal properties of the small asteroid (2867) Steins, we analyzed its surface thermal emission measured by the VIRTIS instrument during the Rosetta spacecraft (ESA) flyby that occurred in September 2008. VIRTIS performed the first thermal mapping of an asteroid surface.
Aims: We determine the thermal properties of di…
A stringent upper limit to SO2 in the Martian atmosphere
Forget, F.; Encrenaz, T.; Atreya, S. K. +6 more
Surfur-bearing molecules have been found at the surface of Mars by the Viking lander, the Spirit and Opportunity rovers, and the OMEGA infrared spectrometer aboard Mars Express. However, no gaseous sulfur-bearing species have ever been detected in the Martian atmosphere. We search for SO2 signatures in the thermal spectrum of Mars at 7.…
Temperature variability in X-ray bright points observed with Hinode/XRT
Kariyappa, R.; Damé, L.; Golub, L. +4 more
Aims: We investigate the variability in temperature as a function of time among a sample of coronal X-ray bright points (XBPs).
Methods: We analysed a 7-h (17:00-24:00 UT) long time sequence of soft X-ray images observed almost simultaneously in two filters (Ti_poly and Al_mesh) on April 14, 2007 with X-ray telescope (XRT) onboard the Hi…
Molecular gas in NUclei of GAlaxies (NUGA). XV. Molecular gas kinematics in the inner 3 kpc of NGC 6951
Schinnerer, E.; Baker, A. J.; Combes, F. +6 more
Within the NUclei of GAlaxies (NUGA) project we have obtained IRAM PdBI and 30 m 12CO(1-0) and 12CO(2-1) observations of the spiral galaxy NGC 6951. Previous work shows that there is indirect evidence of gas inflow from 3 kpc down to small radii: a large-scale stellar bar, a prominent starburst ring (r ≈ 580 pc) and a LINER/S…
Intensity contrast from MHD simulations and HINODE observations
Solanki, S. K.; Lagg, A.; Schüssler, M. +3 more
Context. Changes in the solar surface area, which is covered by small-scale magnetic elements, are thought to cause long-term changes in the solar spectral irradiance, which are important for determining the impact on Earth's climate.
Aims: To study the effect of small-scale magnetic elements on the total and spectral irradiance, we derive th…
Ubiquitous quiet-Sun jets
Martínez Pillet, V.; Quintero Noda, C.; Del Toro Iniesta, J. C.
Context. IMaX/Sunrise has recently reported the temporal evolution of highly dynamic and strongly Doppler shifted Stokes V signals in the quiet Sun.
Aims: We attempt to identify the same quiet-Sun jets in the Hinode spectropolarimeter (SP) data set.
Methods: We generate combinations of linear polarization magnetograms with blue- and reds…
A method for filling gaps in solar irradiance and solar proxy data
Dudok de Wit, T.
Context. Data gaps are ubiquitous in spectral irradiance data, and yet, little effort has been put into finding robust methods for filling them.
Aims: We introduce a data-adaptive and nonparametric method that allows us to fill data gaps in multi-wavelength or in multichannel records.
Methods: This method, which is based on the iterative…
A relationship between the solar rotation and activity in the period 1998-2006 analysed by tracing small bright coronal structures in SOHO-EIT images
Hanslmeier, A.; Wöhl, H.; Brajša, R. +4 more
Aims: The study aims to find a relationship between the rotation of the small bright coronal structures (SBCS) described by the solar rotation parameters and indices of solar activity on monthly and yearly temporal scales.
Methods: We analyse precise measurements of the solar differential rotation determined by tracing SBCS in SOHO-EIT i…
A comparison of preprocessing methods for solar force-free magnetic field extrapolation
Wiegelmann, T.; Valori, G.; Fuhrmann, M. +1 more
Context. Extrapolations of solar photospheric vector magnetograms into three-dimensional magnetic fields in the chromosphere and corona are usually done under the assumption that the fields are force-free. This condition is violated in the photosphere itself and a thin layer in the lower atmosphere above. The field calculations can be improved by …