Structure of the Periphery of the Large Magellanic Cloud Revealed by 2MASS

In order to understand the equilibrium structure of the Large Magellanic Cloud (LMC), I have reexamined the content of the 2MASS database on its periphery. Based on the dereddened colors of the LMC’s red giant branch (RGB) stars, I find an outward radial gradient of decreasing metallicity. The isodensity contours of the RGB stars rule out the existence of a spherical halo on the periphery, and reveal instead an inclined disk. Surprisingly, these density contours also hint that the thickness of the disk traced by metal-weak RGB stars is greater than that traced by the metal-rich RGB. If the stellar population mass-to-light ratio anticorrelates with metallicity, this structure could boost the LMC’s self-microlensing optical depth.