Nested Bubbles of the Northeastern SMC

by Zaytsev and Hanson

Click for larger image

 The image is covering the central part of a large collection of HII regions, supernova remnants (SNRs), and interstellar neutral hydrogen (HI) shells found in the Northeast region of the Small Magellanic Cloud (SMC) spanning about 1.1 kly corresponding to the angular size of the frame at the distance to the SMC (61 kpc). 

The central part of the image is taken by the LHA 115-N 78 HII complex [1] which is about 160 ly across (linear equivalent at a distance to the SMC) featuring many accompanying structures including a planetary nebula candidate [2], open star cluster IC 1624 [3, 4] caught in the crossing of several shock fronts (shown in a cropped image below at 100% of original resolution), complete with great many small scale structures visible in the inner volume of the “main bubble” of the complex.

“torii gate” structure

“torii gate” structure

One of the most noticeable of those small structures is a “torii gate” structure highlighted by red markings on the cropped image below (shown at 200% scale to the original resolution) which is only about 10 arc.sec across, but still corresponding to an impressive 9.6 ly of linear scale (given the distance to the SMC). This particular area could be of interest to study with larger aperture systems.

The list of peculiar objects in this frame is continued by a compact DEM S131 HII region [5] at the top side of the image shown in a cropped image below (at 150% scale to the original resolution) with IKT 25 X-ray binary [6] in the middle which is identified as a Type Ia SNR in [7].

A larger but fainter Q-shaped diffuse structure is visible in the mid-left side of the frame, a part of which is identified as DEM S132 HII region [8].

Many dark nebulae are visible across the frame, many of which are surveyed under [9, 10], showing well against the backdrop of the inner volume of the HII regions. A noteworthy set of nested radial shock fronts is also found in the lower right corner.

Data and initial calibration/integration: Alexandr Zaytsev https://www.astrobin.com/users/m57ring/

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).

12x Ha + 10x OIII + 9x SII guided 1200 sec exposures (10h 20min of combined integral) collected over 7 imaging sessions carried out on Nov 28, 30 of 2023 and Dec 1, 3, 4, 5, 6 of 2023 using Chilescope Telescope #1 system.

Image Processing: Mark Hanson

Partial star suppression applied to highlight the details of the diffuse structures, including those in the backdrop.

DEM S131 HII region

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