Near infrared observations of the star formation region GGD12-15

Abstract

Near infrared imaging observations in JHK broad bands and HZ v=10 S(1) narrow band of the star formation region GGD12-15 are presented in this article. The images reveal young compact infrared clusters and infrared nebulae in association with infrared sources, as well as outflow activities characterized by H 2 emission knots. Most of the infrared point sources are invisible in the optical wave band. The JHK′ photometric results of 76 infrared point sources contain 32 with infrared excess, and 5 with the characteristics of protostars, indicating very active star formation activities in the molecular clouds. Massive stars (defined as those with spectral types earlier than B8) account for ∼ 10 – 26 per cent of all stars of the clusters. The K′ magnitude distribution of GGD12-15 peaks at 15.0 mag, and spreads broadly from 13.0 mag to 16.0 mag. The peak of the [H-K′l color distribution occurs at ∼0.7 mag, above which the redder components of the cluster make up 70 per cent of the total. The newly-discovered H2 emission knots are concentrated in the central area of the clusters, and the spatial distribution has obvious relation to violent star formation activities. Five of the emission knots are located in the central part of the molecular outflow, indicating that they may have been excited by the same source as the molecular outflow.