This HII region lies in the same direction as the radio source W71 and is ionised by the O6 Ib supergiant
LS III +46 12 which is part of the star cluster
Berkeley 90. The cloud surrounding Berkeley 90 (part of which is visible as Sh 2-115) contains 4400 solar masses of gas and dust and is about 30 pc long.
Infrared observations reveal a large, complex structure with multiple bubbles as can be seen in
this MSX image. The nebula is also prominent
at radio frequencies.
LS III +46 12 is part of the open cluster Berkeley 90. BD+46 2972 is unlikely to ionise the nebula because it is located much further away (3400 pc). The cloud surrounding Berkeley 90 (part of which is visible as Sh 2-115) contains 4400 solar masses of gas and dust and is about 30 pc long. The cluster and nebula are located at a distance of 2300 pc.[
1]
This is in the same direction as the radio source W71.[SIMBAD]
This nebula has three exciting stars - DM46 2972 (O9.5 V), DM 46 2978 (B0III) and LS III 46 12 (O6). It is located at an estimated distance of 2300 pc.[
2]
Avedisova gives an O6 Ib class for LS III +46 12. [
3]
Notes
1. ^ Harten, R. & Felli, M. (1980). "The evolved H II Region S 115", Astronomy
and Astrophysics, Vol. 89, 140-144. [1980A&A....89..140H]
2. ^ Felli, M. & Harten, R. H. (1981). "A high-resolution search for
small-scale structure in Sharpless H II regions at 4.995 GHz. II - General
properties of the entire sample. III - Description of selected sources",
Astronomy and Astrophysics, Vol. 100, 28-58. [1981A&A...100...28F]
3. ^ Avedisova, V. S. & Kondratenko, G. I. (1984). "Exciting stars and the
distances of the diffuse nebulae", Nauchnye Informatsii, Vol. 56, 59.
[1984NInfo..56...59A]