A型主序星
The two stars in Serpens Caput that form part of the Snake's body below the heart are Epsilon and Mu Serpentis, both third-magnitude A-type main-sequence stars. Both have a peculiarity: Epsilon is an Am star, while Mu is a binary. Located slightly northwest of Mu is 36 Serpentis, another A-type main-sequence star. This star also has a peculiarity; it is a binary with the primary component being a Lambda Boötis star, meaning that it has solar-like amounts of carbon, nitrogen, and oxygen, while containing very low amounts of iron peak elements. 25 Serpentis, positioned a few degrees northeast of Mu Serpentis, is a spectroscopic binary consisting of a hot B-type giant and an A-type main-sequence star. The primary is a slowly pulsating B star, which causes the system to vary by 0.03 magnitudes.