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.[4] The older star population in this region has an average age of 4–5 million years, and its components are grouped in the open clusterNGC 6604.[2]
Sh 2-54 belongs to an extended nebulosity that includes also the Eagle Nebula and the Omega Nebula.[5] The young high-mass stars of this region constitute the Serpens OB1 and Serpens OB2 OB association.[2]
^ abcReipurth, B. (December 2008). "The Young Cluster NGC 6604 and the Serpens OB2 Association". Handbook of Star Forming Regions, Volume II: The Southern Sky. 5: 590. Bibcode:2008hsf2.book..590R.
^Sofue, Y.; Handa, T.; Fuerst, E.; Reich, W.; et al. (1986). "Giant stellar-wind shell associated with the H II region M16". Publications of the Astronomical Society of Japan. 38: 347–360. Bibcode:1986PASJ...38..347S.