EDP Sciences
Free access
Volume 459, Number 2, November IV 2006
Page(s) L29 - L32
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:20066306

A&A 459, L29-L32 (2006)
DOI: 10.1051/0004-6361:20066306


X-ray accretion signatures in the close CTTS binary V4046 Sagittarii

H. M. Günther1, C. Liefke1, J. H. M. M. Schmitt1, J. Robrade1 and J.-U. Ness2

1  Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg, Germany
    e-mail: moritz.guenther@hs.uni-hamburg.de
2  Arizona State University, School of Earth and Space Exploration, Tempe, AZ, 85287-1404, USA

(Received 28 August 2006 / Accepted 26 September 2006)

We present Chandra HETGS observations of the classical T Tauri star (CTTS) V4046 Sgr . The He-like triplets of $\ion{O}{vii}$, $\ion{Ne}{ix}$, and $\ion{Si}{xiii}$ are clearly detected. Similar to the CTTS TW Hya and BP Tau, the forbidden lines of $\ion{O}{vii}$ and $\ion{Ne}{ix}$ are weak compared to the intercombination line, indicating high plasma densities in the X-ray emitting regions. The $\ion{Si}{xiii}$ triplet, however, is within the low-density limit, in agreement with the predictions of the accretion funnel infall model with an additional stellar corona. V4046 Sgr is the first close binary exhibiting these features. Together with previous high-resolution X-ray data on TW Hya and BP Tau , and in contrast to T Tau , now three out of four CTTS show evidence of accretion funnels.

Key words: X-rays: stars -- stars: individual: V4046 Sagittarii -- stars: pre-main sequence -- stars: coronae -- stars: activity

© ESO 2006