Object 17: Another cluster of emission-line stars near the galactic center

Abstract

Infrared imaging and spectroscopic studies suggest that regions of recent massive star formation exist in the center region of the Galaxy. Here, we present J(1.29 microns), H(1.67 microns), K(2.23 microns), and L'(3.82 microns) broadband images, as well as Br gamma and Br alpha hydrogen recombination line images of the Object #17 detected in a near-infrared survey at a projected distance of 30 pc from the Galactic center. Our data show that this source is a cluster of luminous stars with emission lines. The line flux and width of these stars are similar to those of Of-type stars, Wolf-Rayet stars, and He I emission-line stars recently discovered in the central parsec of the Galaxy. However, although the He II line at 3.09 microns has been detected in Object #17, the He I line at 2.06 microns seems weak. The weakness contrasts with stars in the central parsec of the Galaxy. The broadband colors are consistant with the idea that the #17 cluster is near tha Galactic center, and this consistancy is further evidence for the recent occurrence of massive star formation near the Galactic center. It is possible that this cluster is responsible for the ionization of the thermal arched filaments observed in the radio.