Avedisova concludes that Sh 2-289 is ionised by the B0.5 V class LSS 86
and an uncatalogued B1 V class star (MFJ Sh 2-289 2
). Curiously, she omits two other ionising stars mentioned by MFJ: LS 85
and MFJ Sh 2-289 4
. (Both are B-class according to SIMBAD.)
One huge distance estimate of more than ten thousand parsecs may place this nebula beyond even the Cygnus (Outer) arm. However, closer estimates are also available.
Sh 2-289 is located well below the galactic plane, and this may in part be related to an outer galaxy warp in the third quadrant which bends the galactic disk downwards.
See the Other Outer Arm Objects
in the description of the Monoceros Arc (220° - 210°)
sector in the Commentary on the Galactic Plane
for more information and detailed references.
Describes ionising stars. [1
Sh 2-289 and the galactic warp. [2
1. ^ Moffat, A. F. J., Jackson, P. D., & Fitzgerald, M. P. (1979). "The
rotation and structure of the galaxy beyond the solar circle. I -
Photometry and spectroscopy of 276 stars in 45 H II regions and other young
stellar groups toward the galactic anticentre", Astronomy and Astrophysics
Supplement Series, Vol. 38, 197-225. [1979A&AS...38..197M]
2. ^ Vázquez, Ruben A., May, Jorge, Carraro, Giovanni, et al. (2008). "Spiral
Structure in the Outer Galactic Disk. I. The Third Galactic Quadrant", The
Astrophysical Journal, Vol. 672, 930-939. [2008ApJ...672..930V]