Mass loss at the lowest stellar masses

¹ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany e-mail: matilde@mpia-hd.mpg.de
² Instituto de Astrofísica de Andalucía, CSIC, Camino Bajo de Huétor 50, 18008 Granada, Spain
³ European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany e-mail: fcomeron@eso.org

Received: 10 March 2005
Accepted: 9 June 2005

Abstract

We report the discovery of a jet in a [SII] image of Par-Lup3-4, a remarkable M 5-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 8°) with respect to the plane of the sky. The width of the H_α line suggests a dominating contribution from the accretion columns and from the shocks on the stellar surface. Unresolved H_α emission coming from an object located at 42 from Par-Lup3-4 is detected at a position angle ~30° or ~210°, 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 M 6.5 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.