EVIDENCE FOR AN INTERVENING STELLAR POPULATION TOWARD THE LARGE-MAGELLANIC-CLOUD

We identify a vertical extension of the red clump stars in the color m agnitude diagram (CMD) of a section of the Large Magellanic Cloud (LMC ). The distribution of stars in this extension is indistinguishable in the U, B, V, and I bands - confirming that the detection is real and placing a strong constraint on models of this stellar population. Afte r subtracting the principal red clump component, we find a peak in the residual stellar distribution that is similar to 0.9 mag brighter tha n the peak of the principal red clump distribution. We consider and re ject the following possible explanations for this population: inhomoge neous reddening, Galactic disk stars, random blends of red clump stars , correlated blends of red clump stars (binaries), evolution of the re d clump stars, and red clump stars from a younger LMC stellar populati on. Combinations of these effects cannot be ruled out as the origin of this stellar population. A natural interpretation of this new populat ion is that it consists of ren clump stars that are closer to us than those in the LMC. We derive a distance for this population of similar to 33 to 115 kpc, although the measurement is sensitive to the modelin g of the LMC red clump component. We find corroborating evidence for t his interpretation in Holtzman et al.'s (1997, AJ, 113, 656) Hubble Sp ace Telescope CMD of the LMC field stars. The derived distance and pro jected angular surface density of these stars relative to the LMC star s (less than or similar to 5 to 7%) are consistent with (1) models tha t attribute the observed microlensing lensing optical depth (Alcock ct al. 1997, ApJ, 486, 697) to a distinct foreground stellar population (Zhao 1997,:preprint, astro-ph/9703097) and (2) tidal models of the in teraction between the LMC and the Milky Way (Lin et al. 1995, ApJ, 439 , 652). The first result suggests that the Galactic halo may contain f ew, if any, purely halo MACHO objects. The second result suggests that this new population may be evidence of a tidal tail from the interact ion between the LMC and the Galaxy (although other interpretations, su ch as debris from the LMC-SMC interaction, are possible). We conclude that the standard assumption of a smoothly distributed halo population out to the LMC cannot be substantiated without at least a detailed un derstanding of several of the following: red clump stellar evolution, binary fractions, binary mass ratios, the spatial correlation of stars within the LMC, possible variations in the stellar populations of sat ellite galaxies, and differential reddening - all of which are highly complex. (C) 1997 The American Astronomical Society. [S0004-6256(97)03 812-0].