Henize 2-111 (PN G315.0-00.3) planetary nebula in Centaurus in HOS colors by Zaytsev and Hanson
Remarkable planetary nebula Henize 2-111 (also being referred to as He 2-111, Hen 2-111, and cataloged as PN G315.0-00.3) [1-4] in Centaurus constellation. Type I (helium and nitrogen rich) planetary nebula by Peimbert classification [5], He 2-111 has a planar bipolar asymmetrical shape, which is found to be likely shaped by a triple stellar system in [3, 4]. With estimated distance to the nebula of about 6.8 kly [1-2] and long axis angular length of about 10’ the diameter if the “lobes” corresponds to about 20 ly and the long axis of the core of the nebular of about 30” corresponds to about 1 ly. Thus, the nebula lies much further away than HD 127470 star (830 ly away) - the brightest star in the frame above the core of He 2-111, but roughly at the same distance as a nearby NGC 5617 open cluster (6.5 kly).
The central star (or rather central stars) of this nebula have never been observed, but its core reveals a complex structure featuring a toroid placed at about 45 deg inclination to the plane of the “lobes”, with the outer diameter along the major axis of 20” and inner diameter along the same axis of 14” or 0.7 ly and 0.5 ly of linear size correspondingly, based on the best available distance estimates from above. This toroidal structure in the core turned out to be best visible in the SII channel, and adding it to the exposure set allowed to boost visibility of fine details in the core compared to HO(L)RGB images of this object obtained earlier.
Two sets of “spokes” are reaching out from the core of the nebula to the periphery which consists of fast moving radially extended “knots” of material for which the radial velocity is found to be reaching 650 km/s which put the age of the nebula in the range of 8-20 ky depending on the model of the expansion [1, 2]. A peculiar cusp-like structure is visible next to one of the “spokes” on the left from the core, revealed in a fully connected way in this image, likely for the first time. Extended diffuse structures visible on the outer side of the lobes of the nebula (best visible in the starless version of the image) - also likely for the first time.
ASA Ritchey-Chretien RC-1000: D=1m, f/6.8 on alt-azimuthal direct drive fork mount, FLI ProLine 16803 with secondary mirror based motorized focusing and automatic de-rotation (Telescope #1 system of ChileScope observatory, Río Hurtado Valley, Chile).
Data and initial calibration/integration: Alexandr Zaytsev https://www.astrobin.com/users/m57ring/ 14x Ha + 9x OIII + 8x SII guided 600 sec exposures (5h10m of combined integral) collected over 3 imaging sessions carried out on Jun 11, 12, 13 of 2023 using Chilescope Telescope #1 system.
Image Processing: Mark Hanson
Enjoy, Mark and Alex
[1] https://arxiv.org/abs/1712.01474
[2] https://arxiv.org/pdf/1712.01474.pdf
[3] https://arxiv.org/abs/1606.08149
[4] https://arxiv.org/pdf/1606.08149.pdf
[5] https://articles.adsabs.harvard.edu/pdf/1978IAUS...76..215P
