Tuesday, August 20, 2013

A Great Before/After of Nova Delphini

A user or Reddit today by the name of avdhoeven posted a wonderful picture of the recent nova in Delphinus. It looks like the "before" image is from the Digitized Sky Survey taken in 1990 and the "after" was taken by avdhoeven.

It's a very nice picture to begin with, demonstrating just how drastic of a brightening this relatively minor explosion was. But as with many pictures, I'm always interested in all the other cool bits in the picture.

The first thing that my eye caught was the object to the right. It's slightly bluish and round, so my first though was "Neptune". But the ecliptic doesn't pass anywhere near Delphinus which pretty much rules that out. Then I noticed that there were small "handles" to either side. While these handles were very similar to what Galileo reported when he first looked at Saturn, but again, this couldn't be a planet.

What made it obvious at the end was that there is a small star in the center of the object. Obviously, this was a planetary nebula. Which makes it pretty clear how they got their names. And those small handles? Not rings, but jets. Other redditors already caught that it was NGC 6905.

I also find it interesting because it seems like the "after" image has a longer exposure. Nearly every object is brighter. There's definitely some variable stars that are fainter, but overall, NGC 6905 is also fainter. It's hard to say if that's a consequence of the nebula itself fading and dispersing over the past 2 decades, or different stretching on the image processing.

But perhaps one of the cooler things is a very faint object that someone caught in the upper left. It's a small, red object that moves a tiny bit. I'd completely missed it, but there it is. Once I saw it pointed out, I immediately thought "asteroid". However, that's far too little motion for 23 years apart. An asteroid would be long gone. Instead, it's a high proper motion star.

6 comments:

Planetary Paul said...

Nice, thanks for posting. I'll use this in various astronomy talks.

A. vd Hoeven said...

Thanks for posting this. The original can be found at my site: www.astro-photo.nl


Paul: please use it at your convenience. I would appreciate it when you mention the original source somewhere :)

Planetary Paul said...

Will do!

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