Search Publications
X-rays from T Tauri: a test case for accreting T Tauri stars
Audard, M.; Güdel, M.; Briggs, K. R. +3 more
Context: The generation of X-rays in accreting T Tauri stars (TTS) is thought to be predominantly due to energy dissipation in magnetic fields, but alternative X-ray generation mechanisms have been proposed, such as heating in accretion shocks near the stellar surface, or in shocks forming in jets.
Aims: We test models and trends discussed in …
The gas density around SN 1006
Ballet, J.; Decourchelle, A.; Acero, F.
Context: The density of the ambient medium where the supernova remnant evolves is a relevant parameter for its hydrodynamical evolution, for the mechanism of particle acceleration, and for the emission at TeV energies.
Aims: Using XMM-Newton X-ray observations, we present a study of the ambient medium density of the historical supernova remnan…
Evidence for strong evolution of the cosmic star formation density at high redshifts
Maiolino, R.; Marconi, A.; Mannucci, F. +2 more
Deep HST/ACS and VLT/ISAAC data of the GOODS-South field were used to look for high-redshift galaxies in the rest-frame UV wavelength range and to study the evolution of the cosmic star-formation density at z∼ 7. The GOODS-South area was surveyed down to a limiting magnitude of about (J+Ks)AB = 25.5, looking for drop-out objects in the …
Long term photometric monitoring with the Mercator telescope. Frequencies and mode identification of variable O-B stars
Dupret, M. -A.; Uytterhoeven, K.; Drummond, R. +37 more
Aims: We selected a large sample of O-B stars that were considered as (candidate) slowly pulsating B, β Cep, and Maia stars after the analysis of their hipparcos data. We analysed our new seven passband geneva data collected for these stars during the first three years of scientific operations of the mercator telescope. We performed a frequency an…
The brightest stars of the σ Orionis cluster
Caballero, J. A.
Context: The very young σ Orionis cluster (~3 Ma) is a cornerstone in understanding the formation of stars and substellar objects down to planetary masses. However, its stellar population is far from being completely known.
Aims: This study's purpose is to identify and characterise the most massive stars of σ Orionis to complement current and …
Elusive AGN in the XMM-Newton bright serendipitous survey
Page, M. J.; Carrera, F. J.; Caccianiga, A. +3 more
Context: Optical follow-up of X-ray selected sources finds a significant fraction of “optically dull” sources characterized by optical spectra without obvious signature of AGN activity. In many cases, however, the presence of an AGN is inferred from other diagnostics (e.g. the X-ray properties). Understanding and accounting for this “elusiveness” …
Rapid rotation of a sunspot associated with flares
Yan, X. L.; Qu, Z. Q.
Context: Active region NOAA 10424 observed on August 5, 2003 is studied in detail by using TRACE, SOHO/MDI, BBSO Hα monograph, and GOES data. This investigation focuses on the sunspot rotation and its relation with the eruptive phenomena by analyzing the magnetic configuration that the rotation results in.
Aims: It is shown that there is a clo…
The outburst of the eruptive young star OO Serpentis between 1995 and 2006
Prusti, T.; Siebenmorgen, R.; Hony, S. +4 more
Aims:OO Serpentis is a deeply embedded pre-main sequence star in the Serpens NW star-forming region. The star went into outburst in 1995 and gradually faded afterwards. In many respects its eruption resembled the well-known FU Orionis-type (FUor) or EX Lupi-type (EXor) outbursts. Since very few such events have ever been documented at infrared wav…
The first high-resolution X-ray spectrum of a Herbig star: AB Aurigae
Audard, M.; Güdel, M.; Briggs, K. R. +3 more
Context: The X-ray emission from Herbig Ae/Be stars remains to be explained. In later-type T Tauri stars, X-rays are thought to be produced by magnetically trapped coronal plasma, although accretion-shock induced X-rays have also been suggested. In earlier-type (OB) stars, shocks in unstable winds are thought to produce X-rays.
Aims: We presen…
Physical parameters and multiplicity of five southern close eclipsing binaries
Mészáros, Sz.; Csizmadia, Sz.; Kiss, L. L. +2 more
Aims:We detected tertiary components of close binaries from spectroscopy and light curve modelling, investigated the light-travel time effect and the possibility of magnetic activity cycles, measured mass ratios for unstudied systems, and derived absolute parameters.
Methods: We carried out new photometric and spectroscopic observations of fiv…