Carbon Stars as a Constraint on Models of the Magellanic Stream and as a Kinematical Probe of the Large Magellanic Cloud

Abstract

The high latitude carbon star which appears superimposed on the northern part of the Magellanic Stream (Sanduleak 1980) has been found to be spectroscopically similar to RGO 55 in ω Centauri. Assuming identical luminosities for these two objects, a distance of 38 kpc can be derived to the Magellanic Stream carbon star. The heliocentric radial velocity of the star is — 149 km sec^-1; rather different from the Stream velocity in this direction which is near — 300 km sec ^-1. Current models of the Stream (Lin and Lynden-Bell 1982) can account for the radial velocity of the star even though it differs considerably from that of the HI seen in the same region of the sky only if it is at a distance of about 100 kpc. This large distance is very unlikely and questions either the association of the carbon star with the Stream or current models of it.