BRIGHT NEAR-INFRARED SOURCES WITHIN 1-DEGREES OF THE GALACTIC-CENTER .1. SURVEY AND 1-20 MICRON PHOTOMETRY

A near-infrared survey has been conducted of 0.55 deg2 toward the Galactic center. Additional infrared photometry of 50 objects found in this survey has been made in order to study the nature of luminous stars in the central region of our Galaxy including all sources with K < 7.6 and H - K greater-than-or-equal-to 1.4. Many of the selected objects have large bolometric luminosities M(bol) < -5. However, the number of such bright objects is consistent with a typical exponential-disk model of the distribution of stars and dust, and no evidence has been obtained for any particular concentration of M supergiants in the central region from the present observations. In addition to candidates for normal M-type stars and long-period variables, four objects whose energy spectra peak at approximately 5 pm have been detected in a small region around (1, b) = (0.15-degrees, 0.0-degrees), near the crossing of the 6 cm radio arc with the Galactic plane. These four might be young stellar objects near the Galactic center. Tbe ratio of the extinction at shorter wavelengths to the depth of the silicate absorption at 9.7 mum is A(nu)/tau9.7 = 8 +/- 2 for objects at Absolute value of < 0.2-degrees, similar to those previously determined for the sources in the Galactic center, and that for objects at Absolute value of b > 0.2-degrees is 13 +/- 4, in between of the Galactic center and the solar neighborhood ratios. This suggests that the relative depth change in the silicate absorption is localized to a fairly small region around the Galactic center. On the other hand, the wavelength dependence of interstellar extinction over the range JHKL is derived from the colors of reddened M-type star candidates to be A(lambda) approximately lambda-2.3; the index is slightly smaller (more negative) than most measurements in the solar neighborhood, but the difference might not be significant.