Starship Asterisk*

Yellow Balls in W33

Explanation: Infrared wavelengths of 3.6, 8.0, and 24.0 microns observed by the Spitzer Space Telescope are mapped into visible colors red, green, and blue in this striking image. The cosmic cloud of gas and dust is W33, a massive starforming complex some 13,000 light-years distant, near the plane of our Milky Way Galaxy. So what are all those yellow balls? Citizen scientists of the web-based Milky Way Project found the features they called yellow balls as they scanned many Spitzer images and persistently asked that question of researchers. Now there is an answer. The yellow balls in Spitzer images are identified as an early stage of massive star formation. They appear yellow because they are overlapping regions of red and green, the assigned colors that correspond to dust and organic molecules known as PAHs at Spitzer wavelengths. Yellow balls represent the stage before newborn massive stars clear out cavities in their surrounding gas and dust and appear as green-rimmed bubbles with red centers in the Spitzer image. Of course, the astronomical crowdsourcing success story is only part of the Zooniverse. The Spitzer image spans 0.5 degrees or about 100 light-years at the estimated distance of W33.

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Looks like an photoshopped enhanced M42 to my blind eye.

Thanks for the explanation on the yellow, which one does not often see! Very interesting indeed!

A quick check on Google and this looks like it was in an article in 1978. What gives? "Astronomy and Astrophysics, vol. 65, no. 3, May 1978, p. 307-312. Research supported by the Nederlandse Organisatie voor Zuiver-Wetenschappelijk Onderzoek and Royal Society. (A&A Homepage)"

Absolutely fascinating... And here I thought it was an alien brain...the eyes are the globs on the right of the image...


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Finally! A space formation named after me!

rekesle wrote:A quick check on Google and this looks like it was in an article in 1978. What gives? "Astronomy and Astrophysics, vol. 65, no. 3, May 1978, p. 307-312. Research supported by the Nederlandse Organisatie voor Zuiver-Wetenschappelijk Onderzoek and Royal Society. (A&A Homepage)"

Why is this an issue for you? Yes, that paper was published back in 1978. They took measurements at 2.8, 6, 18 and 21 cm, and drew some conclusions from it.

This APOD, however, is a photograph, taken through filters at "Infrared wavelengths of 3.6, 8.0, and 24.0 microns ... by the Spitzer Space Telescope". Doesn't seem to be a whole lot of overlap there.

Rob

FloridaMike wrote:Finally! A space formation named after me!

Why, do you have an unfortunate condition?

The complexity of what we're seeing in this image isn't really made fully clear by the caption. First of all, we're looking at data collected with two completely different instruments- the two shorter wavelength bands with the IRAC camera, and the long wavelength band with the MIPS camera. All of the data is rather broadband- the 3.6 μm band covers 3-4 μm, the 8 μm band covers 6.4-9.3 μm, and the 24 μm band covers 20-30 μm. That means these sensors are detecting a lot of low temperature thermal blackbody emissions from dust and gas. But in regions like this, you have PAHs, which are hydrocarbon molecules which fluoresce in two of the IRAC band (5.8 μm and 8 μm). Only the 8 μm band is included in today's image, so actually separating PAH emissions from thermal emissions might be tricky. But still, there's a lot going on here.

There is more to this image than yellow balls. I can see the red balls, surrounded by green rings, but can also see green balls with red rings! BUT, the most intriguing thing I see is in the lower left corner. It looks like a red daisy with a series of green balls rising from the centre. MORE INFO on this item, PLEASE!!!!

Qweenie wrote:There is more to this image than yellow balls. I can see the red balls, surrounded by green rings, but can also see green balls with red rings! BUT, the most intriguing thing I see is in the lower left corner. It looks like a red daisy with a series of green balls rising from the centre. MORE INFO on this item, PLEASE!!!!

Red balls with green rings are real. Green balls with red rings are just bright stars and the rings are optical artifacts similar to diffraction spikes (those spiky things coming off stars). The intriguing red daisy with green balls very close to the center is just another very bright star. The perfectly aligned balls are more optical artifacts. They exist only in the image itself and not in reality.

What is the geometrical shape on the lower left of the picture, somewhat like a cartwheel?

joe@eastcoast.co.za wrote:What is the geometrical shape on the lower left of the picture, somewhat like a cartwheel?

Optical artifacts which surround bright stars. That one is especially bright, and so they are especially noticeable. They do not exist as actual structures in the nebula.

The sentence "Yellow balls represent the stage before newborn massive stars clear out cavities in their surrounding gas and dust and appear as green-rimmed bubbles with red centers in the Spitzer image." is confusing (well it is to me!) as it seems to mean that the 'yellow balls' actually appear as "green-rimmed bubbles with red centers" and thus are not the yellow areas in the center of the image that I thought they were (and still do despite the wording!). I appreciate that as nobody else has queried this I may be the only one that finds that sentence to be confusingly worded.