WIYN Open Cluster Study: Lithium in Cool Dwarfs of the M35 Open Cluster

We have obtained high resolution spectra of ∼40 members of M35, determined the Lithium-Teff morphology and the distribution of the rotational velocity for G and K stars, and compared them to those of the Pleiades and other well-known open clusters. 1. The cluster background M35 (NGC 2168) is a very interesting open cluster for several reasons. It is relatively nearby, with (m-M)0=9.7 (Vidal 1973). It is very well populated, with a total mass estimated between 1000 and 3000 M⊙. While M35 is at fairly low galactic latitude (l =186.58, b =2.19), the cluster is rich enough so that it is easy to separate the field stars and the cluster population. At the same time, the reddening is not very high –E(B–V)=0.17, (Vidal 1973). Finally, it has been considered a coeval cluster to the Pleiades, since their turn-off points are located at the similar position on the color-magnitude diagram. The traditional age of the Pleiades is 70-100 Myr. 2. The selection of members. We selected cluster member candidates based on the position of the [V,(V–I)C ] color-magnitude diagram (see Barrado y Navascués et al. 1999). The magnitude interval was 14.5 ≤ V ≤ 17.5, whereas the color range was 0.8 ≤ (V-I)c ≤ 1.6. Since M35 is very close to the galactic plane, we expect some contamination by field stars. In fact, there is not a clear gap between the locus of the M35 Visiting WIYN Observer. The WIYN Observatory is a joint facility of the University of Wisconsin-Madison, Indiana University, Yale University, and the National Optical Astronomy Observatories.