Search Publications
Sedimentation waves on the Martian North Polar Cap: Analogy with megadunes in Antarctica
Le Mouélic, S.; Rodriguez, S.; Spiga, A. +6 more
Complex interactions between katabatic winds and the cryosphere may lead to the formation of sedimentation waves at the surface of ice sheets. These have been first described and named snow megadunes in Antarctica. Here we use topographic data, optical images, subsurface radar soundings and spectroscopic data acquired by Mars orbiters, to show tha…
X-ray observations of VY Scl-type nova-like binaries in the high and low state
Mukai, K.; Orio, M.; Shugarov, S. +1 more
Four VY Scl-type nova-like systems were observed in X-rays during both the low- and the high-optical states. We examined Chandra, ROSAT, Swift and Suzaku archival observations of BZ Cam, MV Lyr, TT Ari and V794 Aql. The X-ray flux of BZ Cam is higher during the low state, but there is no supersoft X-ray source (SSS) as hypothesized in previous art…
The tiny globulettes in the Carina nebula
Gahm, G. F.; Grenman, T.
Context. Small molecular cloudlets are abundant in many H ii regions surrounding newborn stellar clusters. In optical images these so-called globulettes appear as dark silhouettes against the bright nebular background.
Aims: We aim to make an inventory of the population of globulettes in the Carina nebula complex, and to derive sizes and mass…
Single minerals, carbon- and ice-coated single minerals for calibration of GIADA onboard ROSETTA to comet 67P/Churyumov-Gerasimenko
Della Corte, Vincenzo; Ferrari, Marco; Rotundi, Alessandra +1 more
In preparation of the rendezvous of the European Space Agency Rosetta spacecraft with short period Jupiter Family comet 67P/Churyumov-Gerasimenko we undertook the selection and characterization of mineral grains to serve as analogs of dust from the comet. Specifically, these dust analogs are used to calibrate the performance of the onboard Grain I…
A new candidate Wolf-Rayet X-ray binary in NGC 253
Zezas, Andreas; Maccarone, Thomas J.; Hornschemeier, Ann +5 more
We have discovered a persistent, but highly variable X-ray source in the nearby starburst galaxy NGC 253. The source varies at the level of a factor of about 5 in count rate on time-scales of a few hours. Two long observations of the source with Chandra and XMM-Newton show suggestive evidence for the source having a period of about 14-15 hours, bu…
Energetic particle impact on X-ray imaging with XMM-Newton
Kuntz, K. D.; Snowden, S. L.; Thomas, N. E. +3 more
Since energetic protons (∼100 keV) hinder space-based X-ray imaging, there is a need to characterize the proton environments encountered by a soft X-ray mission when planning missions and operations in the near-Earth environment. Impacts range from enhanced noise in the images to damage to CCD detectors. The high-apogee (17.9 RE), incli…
Physical and geometrical parameters of the binary system gliese 150.2
Al-Wardat, M. A.; Balega, Yu. Yu.; Leushin, V. V. +4 more
The speckle interferometric binary system Gl 150.2 (HIP17491) is analyzed using atmosphere modeling and dynamical analysis simultaneously. A synthetic spectral energy distribution (SED) for each of the two components of the system is built using Kurucz blanketed models. These SEDs are combined together to form the total flux, which is compared wit…
Magnetic Helicity of the Global Field in Solar Cycles 23 and 24
Pevtsov, A. A.; Pipin, V. V.
For the first time we reconstruct the magnetic helicity density of the global axisymmetric field of the Sun using the method proposed by Brandenburg et al. and Pipin et al. To determine the components of the vector potential, we apply a gauge which is typically employed in mean-field dynamo models. This allows for a direct comparison of the recons…
The 2XMMi/SDSS Galaxy Cluster Survey. III. Clusters associated with spectroscopically targeted luminous red galaxies in SDSS-DR10
Takey, A.; Schwope, A.; Lamer, G.
We present a sample of 383 X-ray selected galaxy groups and clusters with spectroscopic redshift measurements (up to z ~ 0.79) from the 2XMMi/SDSS Galaxy Cluster Survey. The X-ray cluster candidates were selected as serendipitously detected sources from the 2XMMi-DR3 catalogue that were located in the footprint of the Sloan Digital Sky Survey (SDS…
KK258, a new transition dwarf galaxy neighbouring the Local Group
Wu, Po-Feng; Karachentsev, I. D.; Makarova, L. N. +2 more
Here, we present observations with the Advanced Camera for Surveys on the Hubble Space Telescope of the nearby, transition-type dwarf galaxy KK258 = ESO468-020. We measure a distance of 2.23 ± 0.05 Mpc using the Tip of Red Giant Branch method. We also detect Hα emission from this gas-poor dwarf transition galaxy at the velocity Vh = 92 …