Search Publications
A New Diagnostic Method for Assessment of Stellar Stratification in Star Clusters
Gouliermis, Dimitrios A.; de Grijs, Richard; Xin, Yu
We propose a new method for the characterization of stellar stratification in stellar systems. The method uses the mean-square radius (also called the Spitzer radius) of the system as a diagnostic tool. An estimate of the observable counterpart of this radius for stars of different magnitude ranges is used as the effective radius of each stellar s…
Optical and UV monitor (OM) on-board XMM-Newton
Talavera, Antonio; OMCal Team
The Optical and UV Monitor (OM), is a small telescope co-aligned with the main XMM-Newton X-ray telescopes. It can perform imaging with six broad band lenticular filters covering the range 180 nm to 600 nm. In addition, two grisms allow the user to obtain low resolution spectra in the same range. The detector is an intensified CCD. The instrument …
Pulsed thermal emission from the accreting pulsar XMMU J054134.7-682550
Audard, M.; Walter, R.; Lanz, T. +1 more
Aims: Soft X-ray excesses have been detected in several Be/X-ray binaries and interpreted as the signature of hard X-ray reprocessing in the inner accretion disk. The system XMMU J054134.7-682550, located in the LMC, featured a giant Type II outburst in August 2007. The geometry of this system can be understood by studying the response of the soft…
Driving Currents for Flux Rope Coronal Mass Ejections
Vourlidas, Angelos; Subramanian, Prasad
We present a method for measuring electrical currents enclosed by flux rope structures that are ejected within solar coronal mass ejections (CMEs). Such currents are responsible for providing the Lorentz self-force that propels CMEs. Our estimates for the driving current are based on measurements of the propelling force obtained using data from th…
Speed evolution of fast CME/shocks with SOHO/LASCO, WIND/WAVES, IPS and in-situ WIND data: analysis of kilometric type-II emissions
Gonzalez-Esparza, A.; Aguilar-Rodriguez, E.
Fast CME/shocks propagating in the interplanetary medium can generate kilometric Type II (km-TII) radio emissions at the local plasma frequency and/or its harmonic, so these radio emissions provide a means of remotely tracking CME/shocks. We apply a new analysis technique, using the frequency drift of km-TII spectrum obtained by the Thermal Noise …
Parameter Constraints for High-Energy Models of Colliding Winds of Massive Stars: The Case WR 147
Reimer, A.; Reimer, O.
We explore the ability of high-energy observations to constrain orbital parameters of long-period massive binary systems by means of an inverse Compton (IC) model acting in colliding wind environments. This is particularly relevant for (very) long-period binaries where orbital parameters are often poorly known from conventional methods, as is the …
Young Brown Dwarfs in the Core of the W3 Main Star-Forming Region
Tamura, M.; Ojha, D. K.; Ghosh, S. K. +4 more
We present the results of deep and high-resolution (FWHM ~ 0farcs35) JHK near-infrared (NIR) observations with the Subaru telescope, to search for very low mass young stellar objects in the W3 Main star-forming region. The NIR survey covers an area of ~ 2.6 arcmin2 with 10σ limiting magnitude exceeding 20 mag in the JHK bands. The surve…
The Optical Spectra of Spitzer 24 µm Galaxies in the Cosmic Evolution Survey Field. II. Faint Infrared Sources in the zCOSMOS-Bright 10k Catalog
Kneib, J. -P.; Maccagni, D.; Aussel, H. +67 more
We have used the zCOSMOS-bright 10k sample to identify 3244 Spitzer/MIPS 24 µm-selected galaxies with 0.06 mJy < S 24 µm lsim 0.50 mJy and I AB < 22.5, over 1.5 deg2 of the COSMOS field, and studied different spectral properties, depending on redshift. At 0.2 < z < 0.3, we found that differe…
The low-mass stellar-mass functions of rich, compact clusters in the Large Magellanic Cloud
de Grijs, R.; Hu, Y.; Liu, Q. +2 more
Context: The LMC is an ideal environment for studying stellar MFs, because it contains a large population of compact clusters at different evolutionary stages. We aim to obtain constraints on the initial MFs (IMFs) of our sample clusters on the basis of their present-day MFs, combined with our understanding of their dynamical and photometric evolu…
Weak lensing density profiles and mass reconstructions of the galaxy clusters Abell 1351 and Abell 1995
Dahle, H.; Schirmer, M.; Holhjem, K.
Aims: The aim of the present work is to study the overall mass distribution of the galaxy clusters Abell 1351 and Abell 1995 using weak gravitational lensing. These clusters have a very different mass structure and dynamical state and are the two extremes from a larger sample of 38 X-ray luminous clusters of similar size and redshift.
Methods:…