Sh 2-155 is an ionized H II region with ongoing star formation activity,[1] at an estimated distance of 725 parsecs (2400 light-years) from Earth.

[2][3] Sh 2-155[4] was first noted as a galactic emission nebula in 1959 in the extended second edition of the Sharpless catalogue,[5] being a part of the much larger Cep OB3 Association.

[5] Although Sh 2-155 is relatively faint for amateur observation, some of its structure may be seen visually through a moderately sized telescope under dark skies.

[9] A study of the region's young stellar objects by the Chandra X-ray Observatory and Spitzer Space Telescope shows a progression of stellar ages in front of the cloud, supporting the hypothesis of triggered star-formation.

[12] The name was also used earlier to refer to another brighter but unrelated reflection nebula in Cepheus known as Ced 201[13] or VdB 152,[14][15] positioned at R.A.: 22h 13m 27s Dec.: +70° 15′ 18″ (2000).