THE MORPHOLOGY AND LUMINOSITY FUNCTION OF THE GALACTIC BULGE FROM TMGS STAR COUNTS

The bulge of the Galaxy is analysed by inverting K-band star counts fr om the Two-Micron Galactic Survey in a number of off-plane regions, A total area of about 75 deg(2) of sky is analysed. Assuming a non-varia ble luminosity function within the bulge, we derive the top end of the K-band luminosity function and the stellar density function, whose mo rphology is fitted to triaxial ellipsoids. The luminosity function sho ws a sharp decrease brighter than M-K = -8.0 when compared with the di sc population. By fitting ellipsoids, we find that the bulge is triaxi al with the major axis in the plane at an angle with the line of sight to the Galactic Centre of 12 degrees in the first quadrant. The axial ratios are 1 : 0.54 : 0.33 and the distance of the Sun from the centr e of the triaxial ellipsoid is 7860 pc. The best fit for the stellar d ensity, assuming an ellipsoidal distribution, is D(t) = 1.17(t/2180)(- 1.8) exp[-(t/2180)(1.8)] star pc(-3), for 1300 < t < 3000, where t is the distance along the major axis of the ellipsoid in pc.