EDP Sciences
Free Access
Issue
A&A
Volume 481, Number 2, April II 2008
Page(s) 423 - 432
Section Interstellar and circumstellar matter
DOI https://doi.org/10.1051/0004-6361:20078971
Published online 07 February 2008


A&A 481, 423-432 (2008)
DOI: 10.1051/0004-6361:20078971

Accretion properties of T Tauri stars in $\sigma$ Orionis

T. Gatti1, 2, A. Natta1, S. Randich1, L. Testi1, 3, and G. Sacco4

1  Osservatorio Astrofisico di Arcetri, INAF, Largo E. Fermi 5, 50125 Firenze, Italy
    e-mail: natta@arcetri.astro.it
2  Università di Firenze, Dipartimento di Astronomia, Largo E. Fermi 5, 50125 Firenze, Italy
3  ESO, Karl-Schwarschild Strasse 2, 85748 Garching bei München, Germany
4  Osservatorio Astronomico di Palermo, INAF, Piazza del Parlamento 1, 90134 Palermo, Italy

(Received 31 October 2007 / Accepted 16 January 2008)

Abstract
Accretion disks around young stars evolve in time with time scales of a few million years. We present here a study of the accretion properties of a sample of 35 stars in the $\sim $3 million-year-old star-forming region $\sigma$ Ori. Of these, 31 are objects with evidence of disks, based on their IR excess emission. We use near-IR hydrogen recombination lines (Pa$\gamma$) to measure their mass accretion rate. We find that the accretion rates are significant lower in $\sigma$ Ori than in younger regions, such as $\rho$ Oph, consistently with viscous disk evolution. The He I 1.083 $\mu $m line is detected (either in absorption or in emission) in 72% of the stars with disks, also providing evidence of accretion-powered activity in very low accretors, where other accretion indicators disappear.


Key words: stars: formation -- accretion, accretion disks



© ESO 2008

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.