The balloon borne observation of the galactic infrared radiation, 2

Observation of the galactic radiation near infrared wavelength, at which interstellar extinction becomes comparatively small, can be an effective way of investigating the galactic structure especially in the central region of the galaxy. Observation at 2.4 μm of the central region of the galaxy between l = 350 deg. and 30 deg. using a balloon-borne improved telescope is reported. The central bulge of the galaxy and the very flat and narrow disk component were clearly demonstrated. Strong interstellar extinction concentrated in the galactic plane in the central region of the galaxy was observed. The marked concentration of the surface brightness toward the galactic center clearly implies that the central bulge or the elliptical stellar distribution of the galaxy has been detected. This constitutes the first demonstration of the deep inner structure of the galaxy. The apparent shape of the central bulge must be subject to the interstellar extinction which should be highly concentrated in a narrow zone along the galactic plane. (Yoshimori, M.)