Search Publications
On the nature of dust clouds in the region towards M 81 and NGC 3077
Heithausen, A.
Aims: There is some controversy on the nature of dust clouds found in direction of the interacting galaxy triplett M 81, M 82, and NGC 3077. Are they associated with the tidal arms seen in HI around those galaxies or are they simply Galactic foreground clouds?
Methods: Data from the SPIRE instrument onboard Herschel and MIPS onboard of S…
On the nature of high X-ray luminosities in Sloan Digital Sky Survey galaxies
Alexander, D. M.; Wardlow, J. L.; Watson, M. G. +5 more
Surveys have revealed a class of object displaying both high X-ray luminosities (LX > 1042 erg s-1) and a lack of a discernible active galactic nucleus (AGN) in the optical band. If these sources are powered by star formation activity alone, they would be the most extreme X-ray luminosity star-forming galaxies k…
Extreme ultraviolet solar irradiance during the rising phase of solar cycle 24 observed by PROBA2/LYRA
Dammasch, Ingolf E.; Kretzschmar, Matthieu; Dominique, Marie +3 more
The Large-Yield Radiometer (LYRA) is a radiometer that has monitored the solar irradiance at high cadence and in four pass bands since January 2010. Both the instrument and its spacecraft, PROBA2 (Project for OnBoard Autonomy), have several innovative features for space instrumentation, which makes the data reduction necessary to retrieve the long…
Modelling the multiband spectrum of IGR J17177-3656
Ma, Renyi
The correlation between radio and X-ray luminosity in the hard state of black hole X-ray binaries is important for unveiling the relation between the accretion flow and the jets. In this Letter, we have modelled the quasi-simultaneous multiband observations of a recently discovered transient X-ray source, IGR J17177-3656. It is found that the sour…
Structural Parameters for Globular Clusters in the Outer Halo of M31
Ma, Jun; Wang, Song
In this paper, we present internal surface brightness profiles, using images in the F606W and F814W filter bands observed with the Advanced Camera for Surveys on the Hubble Space Telescope, for 10 globular clusters (GCs) in the outer halo of M31. Standard King models are fitted to the profiles to derive their structural and dynamical parameters. T…
Oxygen Loss from Venus and the Influence of Extreme Solar Wind Conditions
McEnulty, Tess Rose
The purpose of this dissertation is to expand our understanding of oxygen ion escape to space from Venus and its dependence on extreme solar wind conditions found during interplanetary coronal mass ejections (ICMEs). The solar wind dynamic pressure outside of the Venus bow shock did not exceed ∼12 nPa, during 2006-2009, while the solar wind dynami…
Rosetta rendezvous and CONSERT operations in 2014: A chimeric surface model of 67P/Churyumov Gerasimenko
Kofman, Wlodek; Herique, Alain; Rogez, Yves +2 more
In 2014 the European Space Agency's Rosetta probe will rendezvous with the comet 67P/Churyumov Gerasimenko (67P) and the Philae Lander will land on the surface of the nucleus. Following the landing, the COmet Nucleus Sounding Experiment by Radiowave Transmission (CONSERT) radar will perform the tomography of the nucleus by measuring radiowave prop…
Proper Motions and Internal Dynamics in the Core of the Globular Cluster M71
Richer, Harvey B.; Thanjavur, Karun; Goldsbury, Ryan +4 more
We have used Gemini North together with the NIRI-ALTAIR adaptive optics imager in the H and K bands to explore the core of the Galactic globular cluster M71 (NGC 6838). We obtained proper motions for 217 stars and have resolved its internal proper motion dispersion. Using a 3.8 year baseline, the proper motion dispersion in the core is found to be…
Unveiling the nature of two unidentified EGRET blazar candidates through spectroscopic observations
Meintjes, P. J.; Nkundabakura, P.
Studies using the Energetic Gamma-Ray Experiment Telescope (EGRET) revealed that blazars [flat-spectrum radio quasars (FSRQs) and BL Lac objects] emit most of their luminosity in the high-energy gamma-ray (E > 100 MeV) range. From the 271 sources observed by EGRET, 131 are still unidentified. A systematic search is conducted to identify possibl…
Cassini observation of Jovian anomalous continuum radiation
Schippers, P.; Gurnett, D. A.; Hospodarsky, G. B. +4 more
Jovian anomalous continuum is a narrowband electromagnetic radiation near 10 kHz that can escape from Jupiter's magnetosphere to interplanetary space. One possible source mechanism is the magnetosheath re-radiation of the Jovian low frequency radio emissions such as the quasiperiodic (QP) radio emissions, broadband kilometric radiation (bKOM) and …