Volume 453, Number 1, July I 2006
|Page(s)||241 - 252|
|Section||Stellar structure and evolution|
|Published online||09 June 2006|
X-ray and optical bursts and flares in YSOs: results from a 5-day XMM-Newton monitoring campaign of L1551
Astrophysics Division – Research and Science Support Department of ESA, ESTEC, Postbus 299, 2200 AG Noordwijk, The Netherlands e-mail: Giovanna.Giardino@rssd.esa.int
2 Centro de Astrofisica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal
3 INAF – Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
4 Dipartimento di Scienze Fisiche & Astronomiche, Sezione di Astronomia, Piazza del Parlamento 1, 90134 Palermo, Italy
Accepted: 15 February 2006
We present the results of a five-day monitoring campaign with XMM-Newton of six X-ray bright young stellar objects (YSOs) in the star-forming complex L1551 in Taurus. All stars present significant variability on the five-day time scale. Modulation of the light curve on time scales comparable with the star's rotational period appeared to be present in the case of one weak-lined T Tauri star. Significant spectral variations between the 2000 and the 2004 observations were detected in the (unresolved) classical T Tauri binary system XZ Tau: a hot plasma component which was present in the X-ray spectrum in 2000 had significantly weakened in 2004. As XZ Tau N was undergoing a strong optical outburst in 2000, which had terminated since then, we speculate on the possible relationship between episodic, burst accretion, and X-ray heating. The transition object HL Tau underwent a strong flare with a complex temperature evolution, which is indicative of an event confined within a very large magnetic structure (few stellar radii), similar to the ones found in YSOs in the Orion Nebula Cluster.
Key words: stars: pre-main sequence / X-rays: stars / stars: coronae / stars: circumstellar matter
© ESO, 2006
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