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W Orionis

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#1 CarlosEH

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Posted 03 February 2009 - 02:32 PM

I came across an interesting semiregular variable star W Orionis (HD 32736, HR 1648, HIP 23680; 5H 05m 24s, 1* 11m 30s) located at the southern end of Orion's shield on February 2, 2009 (02:00 U.T.) using my 9-inch (23-cm) F/13.5 Maksutov-Cassegrain at 129x. This is a very reddish star as it is a Class C carbon star (C5-4(N5) spectra) being a red giant measuring over 215 solar radii and a luminosity of 4,600 Suns. W Orionis has a peak magnitude of 5.9 (range of 5.9-7.7) with a period of approximately 212 days (it's average brightness varies over a period 2,450 days (6.7 years)). It lies approximately 700 light years from the Sun with a surface temperature between 2,600 to 3,200 Kelvin.

A digital image produced using Photoshop CS3.

Carlos

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#2 CarlosEH

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Posted 03 February 2009 - 02:35 PM

A cropped image of Orion showing the location of W Orionis at the southern end of the shield. The star is indicated by the red marks.

Image provided by Starry Night software.

Carlos

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#3 CarlosEH

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Posted 03 February 2009 - 02:41 PM

I produced an artist's impression of what W Orionis would appear to a space traveler in comparison to the Sun (small yellowish dot to the right of W Orionis). I hope that you like it.

A digital image produced using Photoshop CS3.

Carlos

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#4 rodelaet

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Posted 03 February 2009 - 04:24 PM

Carlos,

An excellent couple of sketches! :jump:

My imagination got triggered right away. X-p

#5 JayinUT

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Posted 03 February 2009 - 04:27 PM

Carlos, you not only made the observation but extended well beyond! I really enjoyed showing W Orionis to our sun and how massive it is. Thanks for your work on this.

#6 Special Ed

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Posted 03 February 2009 - 06:17 PM

Carlos,

"And now for something completely different." :cool: :waytogo:

#7 varmint

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Posted 03 February 2009 - 10:00 PM

Carlos, that's fantastic. I just observed this one last night for the first time and was thinking, now how would I sketch them?

Have you found the one near the edge of Taurus/Auriga/Gemini? That one is in the middle of a rich star field, I was thinking of sketching that one it was the favorite of the evening for me, but tonight I have to test my scopes and make sure they're OK after my accident yesterday.

Here was my observing report.

I also love your size comparison/rendition, I was trying to convey how big they were to my wife, she loved the brilliant color when I showed it to her. Now I can share your sketch with her as an example.

#8 Tommy5

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Posted 03 February 2009 - 10:54 PM

Very interesting and educational set of sketches, these cardon stars are really cool in a scope unfortunately i won't live long enough to see our sun turn into a red giant, so these sketches are the next best thing.

#9 frank5817

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Posted 03 February 2009 - 11:52 PM

Carlos,

Excellent post of this very cool star. :bow: :rainbow: Nice work on capturing the color, then the location in the second drawing and finally the great size comparison. Colorful carbon stars are fun to locate and examine.

Frank :)

#10 CarlosEH

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Posted 04 February 2009 - 12:49 AM

Thank you all for your wonderful compliments on my W Orionis observation and comparison image. I also like to observe carbon stars. Carbon stars are very interesting and are striking in the eyepiece field.

Jim- An excellent report on carbon stars. I recommend everyone to review your post and the links provided by other observers.

Carlos

#11 Rich (RLTYS)

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Posted 05 February 2009 - 07:00 AM

Carlos

Beautiful images. I've been observing W Ori as a variable for years. A beautiful red star in my 12x63 binoculars. Right now W Ori is about mag 6.7.

Thanks for the views.
Rich (RLTYS)

#12 GlennLeDrew

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Posted 07 February 2009 - 03:58 PM

Another thing to put these large giant stars into perspective... Don't let the large diameter mislead you. They're really bloated near-vaccuums, in the outer portions, anyway. The typical mass of a red giant is about 2 times that of the Sun. Even if it started out with, say, 5 solar masses, probably half of that will be circulated back into the ISM by the time it reaches the tip of the asymptotic giant branch (where carbon stars are found.)

So carbon stars are very near the end, where in a mere tens of thousands of years they will shed their outer envelope, exposing the very hot, earth-sized carbon-oxygen core that will for a brief time light up a planetary nebula.

#13 CarlosEH

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Posted 09 February 2009 - 03:46 AM

Glenn and Rich,

Thank you for your compliments on my W Orionis observation and images. I agree that carbon stars are very interesting. I will try to observe more of them in the future.

Carlos






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