2004/04/05 by J. Sanz‐Forcada, J. Sanz-Forcada, E. Franciosini +1 · 2 citations
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Star Formation Studies #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1051/0004-6361:20047159
published as Astron.Astrophys. 421 (2004) 715-727 · 13 pages, 10 figures. Accepted by A&A. Preprints can be found in http://www.astropa.unipa.it/Library/preprint.html
arxiv created 2004/04/05 · openalex publication_date 2004/06/22 · arxiv updated 2009/12/01 · openalex created_date 2022/10/01 · openalex updated_date 2026/07/31
We present XMM-Newton observations of the young ( Myr) cluster around the hot (O9.5V) star σ Orionis AB, aimed at obtaining a high resolution RGS spectrum of the hot star as well as EPIC imaging data for the whole field. We show that the RGS spectrum of σ Ori AB may be contaminated by weaker nearby sources which required the development of a suitable procedure to extract a clean RGS spectrum and to determine the thermal structure and wind properties of the hot star. We also report on the detection of a flare from the B2Vp star σ Ori E and we discuss whether the flare originated from the hot star itself or rather from an unseen late-type companion. Other results of this observation include: the detection of 174 X-ray sources in the field of σ Ori of which 76 are identified as cluster members, including very low-mass stars down to the substellar limit; the discovery of rotational modulation in a late-type star near σ Ori AB; no detectable line broadenings and shifts ( km s-1) in the spectrum of σ Ori AB together with a remarkable low value of the forbidden to intercombination line ratio and unusually high coronal abundances of CNO elements.