Mass loss at the lowest stellar masses

Astrophysics, abstract
astro-ph/0506307

From: Matilde Fernandez [view email]

Date: Tue, 14 Jun 2005 14:14:04 GMT   (991kb)

We report the discovery of a jet in a [SII] image of Par-Lup3-4, a remarkable
M5-type pre-main sequence object in the Lupus 3 star-forming cloud. The
spectrum of this star is dominated by the emission lines commonly interpreted
as tracers of accretion and outflows. Par-Lup3-4 is therefore at the very
low-mass end of the exciting sources of jets. High resolution spectroscopy
shows that the [SII] line profile is double-peaked, implying that the low
excitation jet is seen at a small angle (probably larger than 8 degrees) with
respect to the plane of the sky. The width of the H_alpha line suggests a
dominating contribution from the accretion columns and from the shocks on the
stellar surface. Unresolved H_alpha emission coming from an object located at
4.2" from Par-Lup3-4 is detected at a position angle ~30 degrees or ~210
degrees, with no counterpart seen either in visible or infrared images.We also
confirm previous evidence of strong mass loss from the very low mass star
LS-RCrA 1, with spectral type M6.5 or later. All its forbidden lines are
blueshifted with respect to the local standard of rest (LSR) of the molecular
cloud at a position very close to the object and the line profile of the [OI]
lines is clearly asymmetric. Thus, the receding jet could be hidden by a disk
which is not seen edge-on. If an edge-on disk does not surround Par-Lup3-4 or
LS-RCrA 1, an alternative explanation, possibly based on the effects of mass
accretion, is required to account for their unusually low luminosities.

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