Russeil combines Sh 2-172, Sh 2-173 and Sh 2-177 into one star formation region. All three nebulae lie in the direction of the expanding shell of gas and dust surrounding the
Cas OB5 association.
Russeil identifies 7 possible ionising stars for Sh 2-173, the hottest of which is the O9 V star
ALS 6151 (BD +60 39).
Avedisova associates Sh 2-173 with the star cluster
NGC 103, the radio source
KR 98, and the dark nebula
LDN 1282.
Sh 2-173 appears to be on the edge of the HI shell
GSH 117.8+1.5-35 associated with Cas OB5.
You can view detailed IPHAS hydrogen-alpha images of this nebula
here.
Sh 2-173 is part of the Cas OB5 super shell.[
1]
Russeil combines Sh 2-172, Sh 2-173 and Sh 2-177 into one star formation region. [
2]
Sh 2-173 appears to be on the edge of the HI shell GSH 117.8+1.5-35. [
3]
Notes
1. ^ Moór, A. & Kiss, Cs. (2003). "Multiwavelength Study of the Cas OB5
Supershell", Commmunications of the Konkoly Observatory Hungary, Vol. 103,
149-152. [2003CoKon.103..149M]
2. ^ Russeil, D., Adami, C., & Georgelin, Y. M. (2007). "Revised distances of
Northern HII regions", Astronomy and Astrophysics, Vol. 470, 161-171.
[2007A&A...470..161R]
3. ^ Cichowolski, S., Romero, G. A., Ortega, M. E., et al. (2009). "Unveiling
the birth and evolution of the HII region Sh2-173", Monthly Notices of the
Royal Astronomical Society, Vol. 394, 900-915. [2009MNRAS.394..900C]