APOD: The Pelican Nebula in Red and Blue (2021 Mar 01)

APOD Robot · Post by **APOD Robot** » Mon Mar 01, 2021 5:05 am

The Pelican Nebula in Red and Blue

Explanation: The Pelican Nebula is changing. The entire nebula, officially designated IC 5070, is divided from the larger North America Nebula by a molecular cloud filled with dark dust. The Pelican, however, is particularly interesting because it is an unusually active mix of star formation and evolving gas clouds. The featured picture was processed to bring out two main colors, red and blue, with the red dominated by light emitted by interstellar hydrogen. Ultraviolet light emitted by young energetic stars is slowly transforming cold gas in the nebula to hot gas, with the advancing boundary between the two, known as an ionization front, visible in bright red across the image center. Particularly dense tentacles of cold gas remain. Millions of years from now this nebula might no longer be known as the Pelican, as the balance and placement of stars and gas will surely leave something that appears completely different.

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Ann · Post by **Ann** » Mon Mar 01, 2021 5:56 am

First of all, I love the image! I love the colors! But I must admit that it is kind of hard to see the Pelican.

The Pelican Nebula in red and blue. M. Petrasko, M. Evenden, U. Mishra (Insight Obs.)

The Pelican Nebula. Wikimedia Commons/Tim Stone, Bert Scheuneman, Marco Favro,
Adriano Valvasori, Paolo Demaria, Giuseppe Donatiello

So I want you to take a look at a picture of the Pelican Nebula where it is much easier to see the pelican! That is the picture at right. This is what a numbers mean:

1) 57 Cyg, a nice blue star of spectral class B5
2) The "eye" of the pelican
3) The "corner of the mouth" or the end of the beak
4) The ionization front (also the "neck" of the pelican)
5) The outline of the beak
6) 56 Cyg, a modest A-type star similar to Altair

I have used the same numbers for the APOD. The APOD still doesn't look much like a pelican to me, but please do try to "pelicanize" it in your heads!

Ann

Prof Parker · Post by **Prof Parker** » Mon Mar 01, 2021 9:15 am

Orientation couldn't be more chaotic. Needs to rotate clockwise 90 degrees - and then - mirror reflect (laterally invert), that is the most unforgivable bit.

XgeoX · Post by **XgeoX** » Mon Mar 01, 2021 12:41 pm

Thanks Ann,
I agree it doesn’t look much like a pelican, in fact, without your diagram I would never have made it out! Somebody had a vivid imagination or were on some mind altering substance when they came up with this!

Eric

johnnydeep · Post by **johnnydeep** » Mon Mar 01, 2021 3:32 pm

Yes, thank you, Ann, for your much needed annotations. And even with them it was hard to see the pelican. Here's your pic flipped horizontally and rotated 90 degrees counter-clockwise:

: Ann's Pelican Nebula, Flipped and Rotated to Best See the Pelican; Pelican Nebula annotated 3.jpg (58.47 KiB) Viewed 4520 times

orin stepanek · Post by **orin stepanek** » Mon Mar 01, 2021 4:06 pm

well the pelican is pinkish; but there is a duck under the pelican!

Oh; and yeah; something completely different!

isn't he cute?

Cousin Ricky · Post by **Cousin Ricky** » Mon Mar 01, 2021 7:28 pm

The pelican has always been obvious to me. Maybe because I grew up around pelicans?

Today’s APOD is mirror-reversed.

VictorBorun · Post by **VictorBorun** » Mon Mar 01, 2021 11:35 pm

Prof Parker wrote: ↑Mon Mar 01, 2021 9:15 am Orientation couldn't be more chaotic. Needs to rotate clockwise 90 degrees - and then - mirror reflect (laterally invert), that is the most unforgivable bit.

Or we can mirror-reflect around the diagonal that is near points 1 and 6.

VictorBorun · Post by **VictorBorun** » Mon Mar 01, 2021 11:47 pm

Do I get right:
an ionization front is like a melting front eating away a snow clump. With time the hot transparent zone is claiming more and more of cold and oblique area?
If so, what are the numbers? Is all of the stars' produced energy except neutrinos getting into this phase change?
Is the cold oblique state a thermal insulator compared with hot transparent state?
Does the hydrogen ions' red glow have an analog in the snow melting line?

Starship Asterisk*

APOD: The Pelican Nebula in Red and Blue (2021 Mar 01)

APOD: The Pelican Nebula in Red and Blue (2021 Mar 01)

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