Saturday, July 10, 2021

The Cosmic Zoo!

This is a composite of images taken over several years (2010, 2015, 2018), most recently using a 200mm Pentax lens attached to the U16M as a widefield backdrop for IC1396 (lower left) and SH2-129 (upper right).

IC1396 is a large emission nebula in Cepheus. Radiation from the star HD206267 has cleared out a central portion from the nebula and has also blown away gas and dust radially, resulting in a variety of dark globules that roughly point towards the center.

 These are called "cometary globules" in recognition of their overall shape, which consists of a head followed by a tail of dust that is being blown backwards by HD206267's solar wind. The most conspicuous globule is 1396A, also known as the "Elephant Trunk," which contains a subtle reflection nebula vdb142. Other cometary globules can be appreciated in the full frame version of this image. Although the dark gas and dust are opaque to visible light, infrared light passes through this region easily, permitting a view of the inner workings of the Elephant Trunk. 

SH2-129 is a relatively faint emission nebula in Cepheus, a neighbor of the larger and more often imaged IC 1396. Sometimes referred to as the "Flying Bat" nebula, this region is characterized by Ha emission as well as a small, mixed emission and reflection nebula (vdB 140), seen in the lower portion of the field, just to the left of center. What is most remarkable about this region is a recent discovery made in 2011 by Nicolas Outters, called the "Squid Nebula" due to its shape, but more officially called Ou4. This region is characterized by a very faint OIII emission that has a bipolar shape reminscent of a planetary nebula, seen as the teal-colored region just to the left of center and requiring 10 hours of imaging through an OIII filter to capture (and could have used even more!). Although it was originally thought to perhaps represent a planetary nebula derived from an unknown, dying star, more recent evidence suggests that Ou4 is located within SH2-129 itself and is a bipolar outflow emitting in the OIII spectrum, moving at the same rate as SH2-129, and possibly emanating from a triple star system located in the center of Ou4 (HR8119, visible above as the bright star in the center of the Squid).

Photographic Details:

Dates: Pentax widefield: July 7, 2018 and August 10, 2018; IC1396: August 20, 26, 27, 28, 31 and September 1, 2010; SH2-129: August 25, 26, 27, 28, 2015

Scope: Pentax 200mm lens (2018); Takahashi FSQ106 at f5 (2010 and 2015)

Autoguider: SBIG ST-402 with 60mm guidescope, focal length 227mm

Camera: Apogee U16M at -20C, with 7 position 50mm square filter wheel (Apogee FW50-7S)

Filters: Baader RGB and Ha filters, 50mm square

Exposures: Pentax (2018): Ha, 6 hours; R, 2 hours; G, 2 hours; B, 2 hours, all unbinned. Please check links for IC1396 and SH2-129 for additional exposure details

Post-processing: Calibrated, aligned, and stacked in Maxim, followed by DDP in ImagesPlus (IP). Further processing in Photoshop CS (16 bit format) 

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