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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 559181.0, MPI für Astronomie / Publikationen_mpia
Timescale of mass accretion in pre-main-sequence stars
Authors:Fedele, D.; van den Ancker, M. E.; Henning, Th; Jayawardhana, R.; Oliveira, J. M.
Date of Publication (YYYY-MM-DD):2010
Title of Journal:Astronomy and Astrophysics
Journal Abbrev.:Astronomy and Astrophysics
Start Page:id.A72
Review Status:not specified
Audience:Experts Only
Abstract / Description:We present initial result of a large spectroscopic survey aimed at measuring the timescale of mass accretion in young, pre-main-sequence stars in the spectral type range K0 - M5. Using multi-object spectroscopy with VIMOS at the VLT we identified the fraction of accreting stars in a number of young stellar clusters and associations of ages between 1 - 50 Myr. The fraction of accreting stars decreases from ~60% at 1.5 - 2 Myr to ~2% at 10 Myr. No accreting stars are found after 10 Myr at a sensitivity limit of $10^{-11}$ Msun yr-1. We compared the fraction of stars showing ongoing accretion (f_acc) to the fraction of stars with near-to-mid infrared excess (f_IRAC). In most cases we find f_acc < f_IRAC, i.e., mass accretion appears to cease (or drop below detectable level) earlier than the dust is dissipated in the inner disk. At 5 Myr, 95% of the stellar population has stopped accreting material at a rate of > 10^{-11} Msun yr-1, while ~20% of the stars show near-infrared excess emission. Assuming an exponential decay, we measure a mass accretion timescale (t_acc) of 2.3 Myr, compared to a near-to-mid infrared excess timescale (t_IRAC) of 2.9 Myr. Planet formation, and/or migration, in the inner disk might be a viable mechanism to halt further accretion onto the central star on such a short timescale.
Free Keywords:Astrophysics - Solar and Stellar Astrophysics; Astrophysics - Earth and Planetary Astrophysics
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:URL:http://adsabs.harvard.edu/abs/2009arXiv0911.3320F [ID No:1]
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