APOD: The Tulip in the Swan (2019 Sep 21)

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APOD: The Tulip in the Swan (2019 Sep 21)

Post by APOD Robot » Sat Sep 21, 2019 4:06 am

Image The Tulip in the Swan

Explanation: Framing a bright emission region, this telescopic view looks out across a pretty field of stars along the plane of our Milky Way Galaxy, toward the nebula rich constellation Cygnus the Swan. Popularly called the Tulip Nebula, the reddish glowing cloud of interstellar gas and dust is also found in the 1959 catalog by astronomer Stewart Sharpless as Sh2-101. About 8,000 light-years distant and 70 light-years across the complex and beautiful nebula blossoms near the center of this composite image. Ultraviolet radiation from young energetic O stars at the edge of the Cygnus OB3 association, ionizes the atoms and powers the emission from the Tulip Nebula.

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Ann
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Re: APOD: The Tulip in the Swan (2019 Sep 21)

Post by Ann » Sat Sep 21, 2019 4:52 am

Nice image! I'm always happy to see a beautiful RGB image of a nebula. :D

Where is Cygnus X-1, though? Cygnus X-1 was the first source in the Milky Way to be widely accepted as a stellar mass black hole. I think Cygnus X-1 is located close to the Tulip Nebula, at least as seen from our point of view. Could it by any chance be the fainter of the pair of stars seen at about 5 o'clock, the brighter one yellow, the fainter one slightly blue?

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Re: APOD: The Tulip in the Swan (2019 Sep 21)

Post by Boomer12k » Sat Sep 21, 2019 8:10 am

Ann wrote:
Sat Sep 21, 2019 4:52 am
Nice image! I'm always happy to see a beautiful RGB image of a nebula. :D

Where is Cygnus X-1, though? Cygnus X-1 was the first source in the Milky Way to be widely accepted as a stellar mass black hole. I think Cygnus X-1 is located close to the Tulip Nebula, at least as seen from our point of view. Could it by any chance be the fainter of the pair of stars seen at about 5 o'clock, the brighter one yellow, the fainter one slightly blue?

Ann
It is indeed the yellow star area, under the blue arch, which is the X-1 jet and wave front...here is a cut away view...
http://www.astroeder.com/a-tulipan-kod- ... -1-en.html

Hope that helps...
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Re: APOD: The Tulip in the Swan (2019 Sep 21)

Post by Boomer12k » Sat Sep 21, 2019 8:10 am

Really nice image...

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Re: APOD: The Tulip in the Swan (2019 Sep 21)

Post by orin stepanek » Sat Sep 21, 2019 11:46 am

:thumb_up: :clap: :b: Yes; nice! As Ann & Boomer said!
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Re: APOD: The Tulip in the Swan (2019 Sep 21)

Post by neufer » Sat Sep 21, 2019 5:51 pm

https://en.wikipedia.org/wiki/Tulip wrote:
<<Tulipa (tulips) is a genus of spring-blooming perennial herbaceous bulbiferous geophytes. The word tulip, first mentioned in western Europe in or around 1554 and seemingly derived from the "Turkish Letters" of diplomat Ogier Ghiselin de Busbecq, first appeared in English as tulipa or tulipant, entering the language by way of French: tulipe and its obsolete form tulipan or by way of Modern Latin tulīpa, from Ottoman Turkish tülbend ("muslin" or "gauze"), and may be ultimately derived from the Persian: دلبند‎ delband ("Turban"), this name being applied because of a perceived resemblance of the shape of a tulip flower to that of a turban. This may have been due to a translation error in early times when it was fashionable in the Ottoman Empire to wear tulips on turbans. The translator possibly confused the flower for the turban.>>
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Re: APOD: The Tulip in the Swan (2019 Sep 21)

Post by Ann » Sat Sep 21, 2019 6:54 pm

Boomer12k wrote:
Sat Sep 21, 2019 8:10 am
Ann wrote:
Sat Sep 21, 2019 4:52 am
Nice image! I'm always happy to see a beautiful RGB image of a nebula. :D

Where is Cygnus X-1, though? Cygnus X-1 was the first source in the Milky Way to be widely accepted as a stellar mass black hole. I think Cygnus X-1 is located close to the Tulip Nebula, at least as seen from our point of view. Could it by any chance be the fainter of the pair of stars seen at about 5 o'clock, the brighter one yellow, the fainter one slightly blue?

Ann
It is indeed the yellow star area, under the blue arch, which is the X-1 jet and wave front...here is a cut away view...
http://www.astroeder.com/a-tulipan-kod- ... -1-en.html

Hope that helps...
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Thanks a lot, Boomer! :D

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Re: APOD: The Tulip in the Swan (2019 Sep 21)

Post by MarkBour » Sat Sep 21, 2019 10:17 pm

Capture.PNG
Thank you Ann and Boomer!

Boomer, I had a momentary difficulty comparing your linked image of the Tulip (which then had an accompanying diagram locating Cygnus X-1) to today's APOD. But after staring at them for a bit, I think I can align the two images, with just a slight rotation. If I'm correct, then, incorporating the guidance in your linked image, I've circled the star that may be a companion to X-1 in both images, to the right.

I certainly may be incorrect. There was some mention that the companion was a blue star, but the one I've cricled seems to be the one that Ivan Eder was so labeling on his site.

Interestingly, your linked image was credited to Ivan Eder, but I doubt he is any relation to Robert Eder, who captured today's APOD. Also, oddly, the APOD link from Robert Eder's name below the image appears to be incorrect, at least when I click on it. Robert Eder posts on astrobin (and instagram) and can be found here:
https://www.astrobin.com/users/Robsi/
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Re: APOD: The Tulip in the Swan (2019 Sep 21)

Post by neufer » Sat Sep 21, 2019 10:50 pm

MarkBour wrote:
Sat Sep 21, 2019 10:17 pm

There was some mention that the companion was a blue star,
but the one I've circled seems to be the one that Ivan Eder was so labeling on his site.
HDE 226868 IS the supergiant blue star companion of Black Hole: Cygnus X-1.

It has been reddened by intervening dust in the interstellar medium.
https://en.wikipedia.org/wiki/Cygnus_X-1#HDE_226868 wrote:
<<HDE 226868 is a supergiant star with a spectral class of O9.7 Iab, which is on the borderline between class O and class B stars. It has an estimated surface temperature of 31,000 K and mass approximately 20–40 times the mass of the Sun. Based on a stellar evolutionary model, at the estimated distance of 2,000 parsecs this star may have a radius equal to about 15–17 times the solar radius and is approximately 300,000–400,000 times the luminosity of the Sun. For comparison, the compact [Black Hole] object is estimated to be orbiting HDE 226868 at a distance of about 40 solar radii, or twice the radius of this star. The gas and dust between the Sun and HDE 226868 results in a reduction in the apparent magnitude of the star as well as a reddening of the hue—red light can more effectively penetrate the dust in the interstellar medium. The estimated value of the interstellar extinction (AV) is 3.3 magnitudes. Without the intervening matter, HDE 226868 would be a fifth-magnitude star and, thus, visible to the unaided eye.

The surface of HDE 226868 is being tidally distorted by the gravity of the massive companion, forming a tear-drop shape that is further distorted by rotation. This causes the optical brightness of the star to vary by 0.06 magnitudes during each 5.6-day binary orbit, with the minimum magnitude occurring when the system is aligned with the line of sight. The "ellipsoidal" pattern of light variation results from the limb darkening and gravity darkening of the star's surface.

When the spectrum of HDE 226868 is compared to the similar star Epsilon Orionis, the former shows an overabundance of helium and an underabundance of carbon in its atmosphere. The ultraviolet and hydrogen alpha spectral lines of HDE 226868 show profiles similar to the star P Cygni, which indicates that the star is surrounded by a gaseous envelope that is being accelerated away from the star at speeds of about 1,500 km/s.>>
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Re: APOD: The Tulip in the Swan (2019 Sep 21)

Post by Ann » Mon Sep 23, 2019 6:46 am

MarkBour wrote:
Sat Sep 21, 2019 10:17 pm
Capture.PNG
Thank you Ann and Boomer!

Boomer, I had a momentary difficulty comparing your linked image of the Tulip (which then had an accompanying diagram locating Cygnus X-1) to today's APOD. But after staring at them for a bit, I think I can align the two images, with just a slight rotation. If I'm correct, then, incorporating the guidance in your linked image, I've circled the star that may be a companion to X-1 in both images, to the right.

I certainly may be incorrect. There was some mention that the companion was a blue star, but the one I've cricled seems to be the one that Ivan Eder was so labeling on his site.

Interestingly, your linked image was credited to Ivan Eder, but I doubt he is any relation to Robert Eder, who captured today's APOD. Also, oddly, the APOD link from Robert Eder's name below the image appears to be incorrect, at least when I click on it. Robert Eder posts on astrobin (and instagram) and can be found here:
https://www.astrobin.com/users/Robsi/
Like Art said, HD 226868 is an intrinsically blue star of spectral class B0Ib, which is to say that its surface temperature would be around 30,000 K, and its unreddened B-V index would be at least -0.20. It could well be even more negative (and thus bluer). But the apparent B-V index of HD 226868, as measured from the Earth, is +0.73. That is a huge amount of reddening.

The star "above HD 226868, V1674 Cyg, which looks slightly bluish, has a B-V index of +0.56. In other words, it looks bluer to us than HD 226868 does. But if V1674 Cyg is moderately unreddened, it could be as cool as spectral class F, around, perhaps, 7,000 K.

Ann
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