Search Publications
Constraining the population of cosmic ray protons in cooling flow clusters with γ-ray and radio observations: Are radio mini-halos of hadronic origin?
Enßlin, T. A.; Pfrommer, C.
We wish to constrain the cosmic-ray proton (CRp) population in galaxy clusters. By hadronic interactions with the thermal gas of the intra-cluster medium (ICM), the CRp produce γ-rays for which we develop an analytic formalism to deduce their spectral distribution. Assuming the CRp-to-thermal energy density ratio XCRp and the CRp spectr…
Emergence of magnetic flux from the convection zone into the corona
O'Shea, E.; Galsgaard, K.; Moreno-Insertis, F. +2 more
Numerical experiments of the emergence of magnetic flux from the uppermost layers of the solar interior to the photosphere and its further eruption into the low atmosphere and corona are carried out. We use idealized models for the initial stratification and magnetic field distribution below the photosphere similar to those used for multidimension…
XMM-Newton EPIC observations of 21 low-redshift PG quasars
Porquet, D.; Reeves, J. N.; Brinkmann, W. +1 more
We present an X-ray spectral analysis of 21 low redshift quasars observed with XMM-Newton EPIC. All the sources are Palomar Green quasars with redshifts between 0.05 and 0.4 and have low Galactic absorption along the line-of-sight. A large majority of quasars in the sample (19/21) exhibit a significant soft excess below ∼1-1.5 keV, whilst two obje…
2MASS NIR photometry for 693 candidate globular clusters in M 31 and the Revised Bologna Catalogue
Bellazzini, M.; Galleti, S.; Federici, L. +2 more
We have identified in the 2MASS database 693 known and candidate globular clusters in M 31. The 2MASS J, H, K magnitudes of these objects have been transformed to the same homogeneous photometric system of existing near infrared photometry of M 31 globulars, finally yielding J, H, K integrated photometry for 279 confirmed M 31 clusters, 406 unconf…
Automated recognition of coronal mass ejections (CMEs) in near-real-time data
Berghmans, D.; Robbrecht, E.
This paper presents a new method and first applications of software that we have developed to autonomously detect CMEs in image sequences from LASCO (Large Angle Spectrometric Coronagraph). The crux of the software is the detection of CMEs as bright ridges in (time, height) maps using the Hough transform. The next step employs clustering and morph…
The host of GRB 030323 at z=3.372: A very high column density DLA system with a low metallicity
Pian, E.; Palazzi, E.; Kouveliotou, C. +29 more
We present photometry and spectroscopy of the afterglow of GRB 030323. VLT spectra of the afterglow show damped Lyα (DLA) absorption and low- and high-ionization lines at a redshift z=3.3718±0.0005. The inferred neutral hydrogen column density, log N(H I)=21.90±0.07, is larger than any (GRB- or QSO-) DLA H I column density inferred directly from L…
ISO spectroscopy of disks around Herbig Ae/Be stars
van den Ancker, M. E.; Acke, B.
We have investigated the infrared spectra of all 46 Herbig Ae/Be stars for which spectroscopic data are available in the ISO data archive. Our quantitative analysis of these spectra focuses on the emission bands at 3.3, 6.2, ``7.7'', 8.6 and 11.2 micron, linked to polycyclic aromatic hydrocarbons (PAHs), the nanodiamond-related features at 3.4 and…
On the nature of EIT waves, EUV dimmings and their link to CMEs
Zhukov, A. N.; Auchère, F.
EIT waves and extreme-ultraviolet (EUV) dimmings attract particular attention as they frequently accompany Coronal Mass Ejections (CMEs). We present several examples of EIT waves and EUV dimmings with particular morphologies previously unreported in the literature. We report for the first time an EIT wave in the Fe XV (284 Å) bandpass of the SOHO/…
Grids of model spectra for WN stars, ready for use
Hamann, W. -R.; Gräfener, G.
Grids of model atmospheres for Wolf-Rayet stars of the nitrogen sequence (WN subclass) are presented. The calculations account for the expansion of the atmosphere, non-LTE, clumping, and line blanketing from iron-group elements. Observed spectra of single Galactic WN stars can in general be reproduced consistently by this generation of models. The…
The structure and environment of young stellar clusters in spiral galaxies
Larsen, S. S.
A search for stellar clusters has been carried out in 18 nearby spiral galaxies, using archive images from the Wide Field Planetary Camera 2 on board the Hubble Space Telescope. All of the galaxies have previously been imaged from the ground in UBVI. A catalogue of structural parameters, photometry and comments based on visual inspection of the cl…