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

Free access article

Issue		A&A 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

Letter

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)

Abstract
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

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.