Fundamental properties of pre-main sequence stars in young, southern star forming regions: metallicities

Abstract

Aims: The primary motivation for this project is to search for metal-rich star forming regions, in which, stars of super-solar metallicity will be created, as hopefully, will be extra-solar planets orbiting them ! Results: We find (pre-main sequence) model-dependent isochronal ages of the Lupus, Chamaeleon and CrA targets to be $9.1\pm 2.1$ Myr, $4.5\pm 1.6$ Myr and $9.0\pm 3.9$ Myr respectively. The majority of the stars have Li I 6707.8A equivalent widths similar to, or above those of, their similar mass Pleiades counterparts, confirming their youthfulness. Most stars are kinematic members, either single or binary, of their regions. We find a mean radial velocity for objects in the Lupus cloud to be $\overline{RV}=+2.6\pm 1.8$ km s${}^{-1}$, for the Chamaeleon I & II clouds, $\overline{RV}=+12.8\pm 3.6$ km s${}^{-1}$ whereas for the CrA cloud, we find $\overline{RV}=-1.1\pm 0.5$ km s${}^{-1}$. All stars are coronally and chromospherically active, exhibiting X-ray and H$\alpha$ emission levels marginally less, approximately equal or superior to that of their older IC 2602/2391 and/or Pleiades counterparts. All bar three of the targets show little or no signature of accretion from a circumstellar environment, according to their positions in a J$-$K/H$-$K${}^{{}^{\prime }}$ diagram. We have performed a metallicity analysis for 5 stars in Chamaeleon, 4 stars in Lupus and 3 stars in the CrA star forming regions. These results show that all three regions are slightly metal-poor, with marginally sub-solar metallicities, with $<$[Fe/H]$>=-0.11\pm 0.14$, $-0.10\pm 0.04$ & $-0.04\pm 0.05$ respectively.

28 pages, 9 figures: Accepted (06-Oct-2005) for publication in A&A

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