Sunday, May 21, 2017

A foursome of Planetary Nebulae

After I had seen the 4 planetary nebulae (PNs) in the Messier list, I became fascinated with them so I started to look for more. I found senses of color on some while others were showing a particular structure in it.  But to me, the real challenge was to see the tiny star in the middle of the PN not only visually speaking, but because the amazing atomic story behind it.  In the course of this time in China, I have seen a little more than 20 PNs and sketched some of them so now that the heavy rainy season is about to start in southern China, it is a good time to show some of them.

Let’s start with Cleopatra’s eye, located on the shore of Eridanus river. For some urban stargazers, none of the stars in Eridanus may be visible with the naked eye so they would have to star hop from Rigel in Orion. For those who stargaze from darker skies, the best option is start the journey in the star Zaurak (34 Eri)  and hop back about 3 arc degrees towards Rigel. With only 37.5x it is an obvious dot, but magnification is the name of this game. I achieved the best view with 166x. With direct vision it seemed like a tight and bright core surrounded by a dimmer halo and with averted vision it was possible to see the central star of magnitude 12.2. I referenced the dimmest star in the sketch, of magnitude 13.7.

The second PN in order of my observation was Saturn Nebula, in the constellation of Aquarius. If one has seen M72 or M73 before, Saturn Nebula is just 1 or 2 degrees to the east of them. The night I saw it, seeing was just average (3/5) and it did not let me push the magnification beyond 166x. I could not see much of it, except a pretty bright “egg”.  It kind of resembled the view that I have of the planet Saturn with my 15x70 binoculars except the color. It honestly left me a little dissapointed, specially after seeing sketches in color showing internal structure. But after all I am just using 6” of aperture and those sketches were made with more than 18” of aperture and magnifications of over 500x.

The next one is Eskimo Nebula in Gemini. It escorts the twin brothers from a position just 2 degrees east of the star  Wasat, in the waist of Pollux. Visually, it seemed to make a perfect match with the star HIP36370 (Mag 8.20) with the only difference in color: The PN seemed to shine on greyish blue while the companion star in white. With averted vision, one can also see an small halo around the star, which shows similar color. I feel pleased with the view of this PN in my telescope, but once again magnification and large aperture will give a more details on this PN.

Finally we have NGC 2346,  Butterfly Nebula. It is bipolar PN located in Monoceros. I was expecting to see some glance around the star or something else but frankly I saw nothing other than the centar star.  I can’t blame my small telescope only, because the light polluted sky helped to washed out the nebular details. At the time of the observation, Monoceros was exactly in the most light polluted area from my suburban sky and since I came to China in 2014, I have noticed that the glance from the city had grown. On multiple times I tried to convince myself to see something else more than a stellar object in this PN, but  I just simply could not see more.  I guess a darker sky and a nebula filter such a OIII filter would reveal more details even with the same aperture.

Now, I am glad to introduce you all to the foursome of PNs:

I made this collage with enough size to be enjoyed with a higher resolution. You can also click on every raw image to see it in detail and check the notes if they are of some help.

Once again, thanks for reading my blog and see you next time.


Edited by Jennifer Steinberg (editor in chief).

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