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We report the discovery of a medium-strength (∼0.5 kG) magnetic field on the young, massive star τ Sco (B0.2 V), which becomes the third-hottest magnetic star known. Circularly polarized Zeeman signatures are clearly detected in observations collected mostly with the ESPaDOnS spectropolarimeter, recently installed on the 3.6-m Canada–France–Hawaii(More)
We present a set of maximum entropy reconstructions of the starspot distributions on two rapidly rotating G dwarfs in the Persei Cluster, from spectra taken at the William Herschel Telescope on three nights in 1996 October and November. Since these stars are too faint for conventional Doppler imaging, which makes use of only one or a few lines, we take the(More)
We present in this paper the first results of a spectropolarimetric analysis of a small sample (∼ 20) of active stars ranging from spectral type M0 to M8, which are either fully-convective or possess a very small radiative core. This study aims at providing new constraints on dynamo processes in fully-convective stars. The present paper focuses on 5 stars(More)
Studies of stellar magnetism at the pre-main sequence phase can provide important new insights into the detailed physics of the late stages of star formation , and into the observed properties of main sequence stars. This is especially true at intermediate stellar masses, where magnetic fields are strong and globally organised, and therefore most amenable(More)
Context. The chemically peculiar HgMn stars are a class of Bp stars which have historically been found to be both non-magnetic and non-variable. Remarkably, it has recently been demonstrated that the bright, well-studied HgMn star α And exhibits clear Hg ii line profile variations indicative of a non-uniform surface distribution of this element. Aims. With(More)
We investigate the magnetic geometry of the active G8 dwarf ξ Bootis A, from spec-tropolarimetric observations obtained in 2003 with the MuSiCoSéchelle spectropo-larimeter at the Télescope Bernard Lyot (Observatoire du Pic du Midi, France). We repeatedly detect a photospheric magnetic field, with periodic variations consistent with rotational modulation.(More)
Magnetism in pre-MS intermediate-mass stars and the fossil field hypothesis Abstract. Today, one of the greatest challenges concerning the Ap/Bp stars is to understand the origin of their slow rotation and their magnetic fields. The favoured hypothesis for the latter is the fossil field, which implies that the magnetic fields subsist throughout the(More)
We report the discovery, using FORS1 at the ESO-VLT and ESPaDOnS at the CFHT, of magnetic fields in the young A-type stars HD 101412, V380 Ori and HD 72106A. Two of these stars (HD 101412 and V380 Ori) are pre-main sequence Herbig Ae/Be (HAeBe) stars, while one (HD 72106A) is physically associated with a HAeBe star. Remarkably, evidence of surface abundance(More)
The Chandra X-ray observatory monitored the single cool star, AB Doradus, continuously for a period lasting 88 ksec (1.98 P rot) in 2002 December with the LETG/HRC-S. The X-ray lightcurve shows rotational modulation, with three peaks that repeat in two consecutive rotation cycles. These peaks may indicate the presence of compact emitting regions in the(More)
We report results of an extended spectropolarimetric and photometric monitoring of the weak-line T Tauri star V830 Tau and its recently-detected newborn close-in giant planet. Our observations , carried out within the MaTYSSE programme, were spread over 91 d, and involved the ESPaDOnS and Narval spectropolarimeters linked to the 3.6-m Canada-France-Hawaii,(More)