RT Journal Article
T1 X-ray variability of sigma Orionis young stars as observed with rosar
A1 Caballero, J. A.
A1 López Santiago, J.
A1 Castro Rubio, Elisa De
A1 Cornide Castro-Piñeiro, Manuel
AB We used the Aladin Virtual Observatory tool and High Resolution Imager ROSAT archival data to search for X-ray variability in scale of days in 23 young stars in the sigma Orionis cluster and a background galaxy. Five stars displayed unambiguous flares and had probabilities p(var) >> 99% of being actual variables. Two of the detected flares were violent and long lasting, with maximum duration of six days and amplitude of eight times above the quiescent level. We classified another four stars as possible X-ray variables, including the binary system formed by the B2Vp star sigma Ori E and its close late-type companion. This makes a minimum frequency of high-amplitude X-ray variability in excess of a day of 39% among sigma Orionis stars. The incidence of this kind of X-ray variability seems to be lower among classical T Tauri stars with mid-infrared flux excesses than among fast-rotating, disk-less young stars.
PB IOP Publishing ltd
SN 0004-6256
YR 2009
FD 2009-06
LK https://hdl.handle.net/20.500.14352/44625
UL https://hdl.handle.net/20.500.14352/44625
LA eng
NO © 2009. The American Astronomical Society. All rights reserved. We are grateful to the anonymous referee, J. F. Albacete Colombo, and J. Sánz Forcada for helpful discussion and advice. Financial support was provided by the Universidad Complutense de Madrid, the Comunidad Autónoma de Madrid, the Spanish Ministerio Educación y Ciencia, and the European Social Fund under grants: AyA200502750, AyA2005-04286, AyA2005-24102-E, AyA2008-06423C03-03, AyA2008-00695, PRICITS-0505/ESP-0237, and CSD2006-0070. This research has made use of the SIMBAD, operated at Centre de Données astronomiques de Strasbourg, France, and the NASA's Astrophysics Data System.
NO Universidad Complutense de Madrid
NO Comunidad Autónoma de Madrid
NO Spanish Ministerio Educación y Ciencia
NO European Social Fund
DS Docta Complutense
RD 7 abr 2025