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WR 134 Ring Nebula

Explanation: Made with narrow and broad band filters, this colorful cosmic snap shot covers a field of view about the size of the full Moon within the boundaries of the constellation Cygnus. It highlights the bright edge of a ring-like nebula traced by the glow of ionized hydrogen and oxygen gas. Embedded in the region's interstellar clouds of gas and dust, the complex, glowing arcs are sections of bubbles or shells of material swept up by the wind from Wolf-Rayet star WR 134, brightest star near the center of the frame. Distance estimates put WR 134 about 6,000 light-years away, making the frame over 50 light-years across. Shedding their outer envelopes in powerful stellar winds, massive Wolf-Rayet stars have burned through their nuclear fuel at a prodigious rate and end this final phase of massive star evolution in a spectacular supernova explosion. The stellar winds and final supernovae enrich the interstellar material with heavy elements to be incorporated in future generations of stars.

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Wolf Rayet nebulae are some of my favourite objects in the sky and I'm totally gobsmacked and overjoyed to see an image of one featured!! Don Goldman is excellent at bringing out fine detail through narrowband filters and the OIII arc is lovely! The rich vivid colours are also a surprise, Cygnus seems to be filled with wonderful colourful obscure treasures. I believe this is the first colour image of this enigmatic nebula, which was discovered in 1971. Hope it brings a smile to Ann!

I was sure the shedding link was going lead me to cat picture. Sadly no cats today.
todays picture looks like it's kind of windy. Must be caused by duckling instability.

starfsurfer wrote:

Hope it brings a smile to Ann!

The picture does make me smile, but it also makes me mystified.

The reason for my smile is, of course, the vivid and colorful beauty of the picture. I love the brilliant red Ha nebulosity and the blue OIII nebulosity on the right. I love the many colorful stars, but the star colors are precisely the reason for my mystification.

Consider the red star at upper right. It is an M0 star whose color index is more than +2.0: check! Its orange-red color is exactly what you would expect from such a star!

Consider the brilliantly blue star near the center. It is classified as a B8V star, and it has a tiny parallax, 1.86 ± 0.75 milliarcseconds. Assuming you can trust the parallax - which is far from certain since the measured parallax is well within the margin of error - the distance to this star is about 1700 light-years. I must admit that if you combine the apparent magnitude of the star with the tiny parallax of 1.86 ± 0.75 milliarcseconds, you get a luminosity for the star which seems very reasonable for a B8V star, about 85 times that of the Sun. So the distance may be correct.

This blue star is also really blue in color. Not only is it intrinsically blue since it is of spectral class B, but its "Hipparcos B-V index" is in fact negative, -0.012. It is remarkable that a star so far away, sitting in the dust lane of the Milky Way, should be so extremely little reddened. Anyway, I love the blue star!
Okay, but now lets proceed to WR 134 itself, or HD 191765, as I prefer to call it. Its color in today's APOD is a sort of pinkish purple. But its B-V index is relatively low and relatively close to zero. Its "Hipparcos B-V index" is 0.219, and its "Johnson B-V index" is as low as 0.03. That is definitely as blue as an A-type star. Consider Altair, for example, the alpha star of the constellation Aquila: This A7IV star has a luminosity of 11 stars like the Sun and a "Johnson B-V index" of +0.22. Its Hipparcos B-V index is +0.23. So WR 134 is bluer than Altair - any way you look at it, it is bluer - but it looks redder. Hmmm.

Could the pinkish-purple color of WR 134 in today's APOD be due to Ha emission? But you'd think that a Wolf-Rayet star would have lost most of its outer hydrogen, so that the Ha emission would not come from the star itself. And my impression is that Wolf-Rayet stars tend to look bluish. Consider bipolar nebula NGC 6164 surrounding WR star HD 148937. The apparent color of HD 148937 is redder (Johnson +0.32, Hipparcos + 0.30) than the apparent color of WR 134. Still WR 134 looks purple in today's APOD, while HD 148937 looks blue in most pictures.

I'd love to hear a comment from Don Goldman himself and hear him comment on the purple color of WR 134 in his picture.

But like I said, I agree with starsurfer that today's APOD is very beautiful!

Ann

Are the straight lines radiating to the lower left (at 8 O'Clock) and upper left (11 O'Clock) in the image artifacts? If not, what are they?

The insgnifant one was handed a gift yesterday and it was a unexpetedly curious young 9 year old girl. My better half started tutoring this girl yesterday for she is the biggest social butterfly according to mom. My better half asked her to write down some things about which she wants to learn this summer. What came back was this unexpected gift. She wants to learn about black holes and the solar system, stars, galaxies and she actually said quasars. WOW, the insignificant one will always be that, but I have a chance here to nurture a young future scientist in ways i cannot possibly be garanteed success. This young girl is exactly what I imagined the young lady, a physicist, sitting in the audience, not with the panel table by the podium, during the NASA tv conference on the Nustar sattelite recently aired, and lauched, . It would be amazing if I could somehow, anonimously, connect the two.

ta, that's great! Some resources which might be useful: http://asterisk.apod.com/viewtopic.php?f=30&t=26458

thank you Ow. Our first project is going to be going down to the vellum paper store and get a 33 foot long roll. Then we will lay out the distance from the sum at one end and Neptune on the other end. And as the solar system lesson progresses we will fill out to scale all the planets within. Brilliant pass me an ice cold one

ta152h0 wrote:thank you Ow. Our first project is going to be going down to the vellum paper store and get a 33 foot long roll. Then we will lay out the distance from the sum at one end and Neptune on the other end. And as the solar system lesson progresses we will fill out to scale all the planets within. Brilliant pass me an ice cold one :D :D :D :D

I do this with my students. A roll of calculator tape works nicely, because it's long enough that you can scale the planets large enough to see them (at the same scale as distance), and it's cheap.