New Light on Young Stars:
Spitzer's View of Circumstellar Disks

Intensive Mass Loss from an Evolved Disk in the Sigma Ori Cluster

First Author:
Elisabetta Rigliaco
Email: erigliaco AT arcetri.astro.it
INAF/Osservatorio Astrofisico di Arcetri
Largo E.Fermi, 5
Firenze, 50125, Italy
Coauthors:
Natta, Antonella, INAF/Osservatorio Astrofisico di Arcetri
Randich, Sofia, INAF/Osservatorio Astrofisico di Arcetri
Sacco, Germano, INAF/Osservatorio Astrofisico di Palermo

Abstract

We present a study of the accretion properties of the object SO587, a 0.3 solar mass star in the sigma Ori cluster which is surrounded by an evolved disk (Hernandez et al.,2007). The Hα profile is rather narrow and single-peaked; the accretion rate derived from the U-Band excess emission is low (of the order of about 10^-10 Msun/yr. However the optical spectrum of this star shows strong emission in the forbidden lines of NII, OI and SII (Zapatero-Osorio et al.,2002; Sacco et al.,2008). If these lines are interpreted as coming from a wind,they correspond to a mass loss rate of about 10^-9 Msun/yr,i.e. to a very low ratio M_acc/M_wind. In this poster we explore this as well as other scenarios, and discuss their implications.
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