APOD: The Bubble and M52 (2011 Sep 14)

[APOD Robot]

The Bubble and M52

Explanation: To the eye, this cosmic composition nicely balances the Bubble Nebula at the lower right with open star cluster M52. The pair would be lopsided on other scales, though. Embedded in a complex of interstellar dust and gas and blown by the winds from a single, massive O-type star, the Bubble Nebula, also known as NGC 7635, is a mere 10 light-years wide. On the other hand, M52 is a rich open cluster of around a thousand stars. The cluster is about 25 light-years across. Seen toward the northern boundary of Cassiopeia, distance estimates for the Bubble Nebula and associated cloud complex are around 11,000 light-years, while star cluster M52 lies nearly 5,000 light-years away. The wide telescopic field of view spans about 1.5 degrees on the sky or three times the apparent size of the Full Moon.

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[Boomer12k]

Awesome, I love bubble nebulas. I will try to take a picture when the smoke clears. Jupiter is less than half bright because of the smoke from forest fires.

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[Ann]

This is a very pretty pair. To my knowledge and recollection, the Bubble Nebula is the only bubble-shaped nebula known in our galaxy that is not blown by the central star of a planetary nebula or by a supernova remnant. M52 looks nice in the general neighbourhood, give or take a couple of thousand light-years( ). Note the bright blue star next to the Bubble Nebula. I don't have my software here right now so that I can check it up, but I'm pretty sure that it is an intrinsically really hot and bright blue star.

I'm a bit surprised at the distance estimates coupled with size estimates for the Bubble Nebula and M52. M52 is around 5,000 light-years away and spans about 25 light-years. The Bubble Nebula is around 11,000 light-years away and spans about ten light-years. Doesn't that mean that the Bubble Nebula ought to look much smaller than M52, much more so than it actually does?

Ann

[Indigo_Sunrise]

I'm a bit surprised at the distance estimates coupled with size estimates for the Bubble Nebula and M52. M52 is around 5,000 light-years away and spans about 25 light-years. The Bubble Nebula is around 11,000 light-years away and spans about ten light-years. Doesn't that mean that the Bubble Nebula ought to look much smaller than than M52, much more so than it actually does?

Ann

This is what I was thinking, too.


Very beautiful image, though!

[Science4Man]

I'm a bit surprised at the distance estimates coupled with size estimates for the Bubble Nebula and M52. M52 is around 5,000 light-years away and spans about 25 light-years. The Bubble Nebula is around 11,000 light-years away and spans about ten light-years. Doesn't that mean that the Bubble Nebula ought to look much smaller than than M52, much more so than it actually does?

Ann

Doing the math using the numbers in the article, M52 angular extent is 25/5000 = 5 mrad, the bubble nebula would be 10/11000 = 0.9091 mrad. I could agree if the author was just talking about the bubble alone compared to M52 but the author said Bubble and associated complex.

[neufer]

I'm a bit surprised at the distance estimates coupled with size estimates for the Bubble Nebula and M52. M52 is around 5,000 light-years away and spans about 25 light-years. The Bubble Nebula is around 11,000 light-years away and spans about ten light-years. Doesn't that mean that the Bubble Nebula ought to look much smaller than than M52, much more so than it actually does?

Doing the math using the numbers in the article, M52 angular extent is 25/5000 = 5 mrad, the bubble nebula would be 10/11000 = 0.9091 mrad. I could agree if the author was just talking about the bubble alone compared to M52 but the author said Bubble and associated complex.

The Bubble Nebula (NGC 7635) has apparent dimensions of 15′ × 8′
and contains within it a much smaller 10 ly diameter bubble.

M52 with apparent dimensions of 13′ (= 3.8 mrad) is more like 19 ly in diameter.

[Science4Man]

I'm a bit surprised at the distance estimates coupled with size estimates for the Bubble Nebula and M52. M52 is around 5,000 light-years away and spans about 25 light-years. The Bubble Nebula is around 11,000 light-years away and spans about ten light-years. Doesn't that mean that the Bubble Nebula ought to look much smaller than than M52, much more so than it actually does?

Ann

Doing the math using the numbers in the article, M52 angular extent is 25/5000 = 5 mrad, the bubble nebula would be 10/11000 = 0.9091 mrad. I could agree (with the article text) if the author was just talking about the bubble alone compared to M52 but the author said Bubble and associated complex.

Sorry for the incomplete thought on my previous entry. The conclusion being, Ann is right! The numbers presented do not appear to match the picture.

[orin stepanek]

I like the bubble nebula it is quite interesting. I don't know if size comparison with M52 is accurate but that takes nothing away from this picture.

[Iron Sun 254]

Yes, it's just the central bubble that matches the diameter mentioned in the description and that appears smaller than the open cluster.

[StarDust]

To Ann (and others), my thanks for speaking up about your confusion! Misery loves company.
I wanted to teach my niece something about optical illusion and perspective, how the brain (mis)perceives dimensions and distance. So, I slowly went line by line through the accompanying explanation using supplemental gnarled hand gestures and creative analogies, only to watch my careful tutelage fall apart with the sentence "distance estimates for the Bubble Nebula and associated cloud complex are around 11,000 light-years, while star cluster M52 lies nearly 5,000 light-years away."
WTF?? How did I paint myself into a corner that even the tempting but lame offer - "let's go get ice cream" - failed to extricate?
Uncle StarDust isn't often flustered, but Science4Man's math lesson (hate higher math) further obscured the field of view like pigeon droppings on binocular lenses... until I read his completed thought.
I still hope to regain some semblance of credibility with my niece. Hopefully, someone will explain (using layman's English) how a significantly smaller-sized but larger-appearing object is twice as distant? This does not compute.
Googling "distance from earth" did nothing to help as the Bubble is still considered the more distant of the two:
M52 - The distance of this cluster is not very well known; Kenneth Glyn Jones adopts 3,000, Mallas/Kreimer 7,000 light years, while the Sky Catalogue 2000.0 gives 5,200 (i.e., 1,600 pc) and Götz 5,050 light years. Robert Garfinkle, in his "Star Hopping", quotes about 3,000, Harvey Pennington and George Kepple and Glen Sanner's Night Sky Observer's Guide 3,900 light years. REF1- http://www.seds.org/messier/m/m052.html
NGC 7635 - Bubble Nebula: At a distance of 7,100 light-years from Earth, the Bubble Nebula is located in the constellation Cassiopeia and has a diameter of 6 light-years. REF2- http://hubblesite.org/newscenter/archiv ... 4/image/a/

[StarDust]

I concur with Iron Sun's concise reply that arrived just before my own ramblings. The explanation should have confined the comparison to just the central bubble.

[neufer]

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[BMAONE23]

Click to play embedded YouTube video.

[Rolllz]

Indeed the Information supplied in the article is askew. Perhaps a finer degree of editing would have helped.

[Wolf Kotenberg]

I got me a feeling the universe is so big that no matter where I could travel, it would look the same ( caveat- not get real close to any star, including a black hole ) By the way, is a black hole considered a star ?

[neufer]

By the way, is a black hole considered a star ?

No.

[starman]

With reference to the 'angular size anomaly' it's necessary to remember that the bubble nebula in the photo may well extend out beyond the visible part you can see. What would be better is an image taken in the IR. The OB-association near M52 is very large and dynamic. It spills over into Cepheus nearby.