In its core there are many protostars and many infrared sources; some of these sources, like IRAS 18151−1208, are most probably very young high-mass stars. The older star population in this region has an average age of 4-5 millions years, and its components are grouped in the open clusterNGC 6604.
^ abcReipurth, B. (December 2008). "The Young Cluster NGC 6604 and the Serpens OB2 Association". Handbook of Star Forming Regions, Volume II: the Southern Sky5: 590. Bibcode:2008hsf2.book..590RCheck |bibcode= value (help).