INFRARED OBSERVATIONS OF PECULIAR CARBON STARS

We present a uniform and high quality set of infrared photometric (JHK ) observations of the 6 peculiar carbon giant stars V Ari. UV Cam. BD34 911, TU Gem, BD+57 2161 and BD+34 4134. All of these belong to the small group of known cool CH giants populating the Galactic halo. Comp arison of the J - H and H - K colours to ''normal'' C stars show our s tars to be ''bluer'' (i.e., having lower values of J - H and H - K) th an the bulk of the Galactic C stars. Comparison with synthetic J H K c olours reveal 5 of our 6 stars as having considerably lower metallicit ies and/or higher temperatures than the bulk. Using standard assumptio ns we derive estimates of their effective temperatures, gravities, lum inosities and distances. Their derived luminosities place them close t o (or below) the theoretical first He shell flash luminosity although other observations indicate their carbon excess to be intrinsic.