Starship Asterisk*

Seagull Nebula over Pinnacles' Peak

Explanation: The bird is bigger than the peak. Nicknamed for its avian shape, the Seagull Nebula is an emission nebula on the night sky that is vast, spanning an angle over five times the diameter of the full moon and over 200 light years. The head of the nebula is catalogued as IC 2177, and the star cluster under its right wing is catalogued as NGC 2343. Consisting of mostly red-glowing hydrogen gas, the Seagull Nebula incorporates some dust lanes and is forming stars. The peak over which this Seagull seems to soar occurs at Pinnacles National Park in California, USA. The featured image is a composite of long exposure images of the background sky and short exposure images of the foreground, all taken consecutively with the same camera and from the same location.

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What i like best about this APOD is that the Seagull Nebula is really red. Because it is really red. Yeah, with the help of narrowband photography you can bring out other colors in it, but honestly, it's just so red.

What I don't like much about the APOD is that it doesn't bring out any blue light at all in any of the stars or in any parts of the nebula. That's bad, because there really are stars and small nebulas in the larger Seagull Nebula that really are bluish.


Patrick Cosgrove's picture is a narrowband one, and the blue color probably means OIII. You can't be sure that an object that looks blue in a narrowband image would look blue in an RGB image, but this RGB+HαOIII picture by Matt Harbison shows FN CMa as blue, too:


So much for the color of today's APOD. An interesting aspect of the picture is that it makes the Seagull Nebula look absolutely huge in the sky. So how big is it really? The best I can do for you is how you this image of hydrogen alpha nebulas in the sky in black and white:


So as you can see, the Seagull Nebula is smaller than Barnard's Loop in Orion (the big C-shaped thing in Orion). It's smaller than the Lambda Orionis Nebula (the big round thing to the upper right of Barnard's Loop). But it is a lot bigger than the Orion Nebula (the brilliantly bright small object inside Barnard's Loop).

But if you want to see the Seagull Nebula and its surroundings in its full glory, take a look at this gorgeous image by Matt Harbison:

Ann

This gorgeous nebula always make me think of Godzilla’s Rodan, rather than a seagull.

What is the distance of the Seagull Nebula from earth?

Astronut wrote: ↑Wed Feb 21, 2024 11:36 am What is the distance of the Seagull Nebula from earth?

https://apod.nasa.gov/apod/ap090327.html

Well, an old APOD mentioned this.

Dominated by the reddish glow of atomic hydrogen, the complex of cosmic gas and dust clouds with bright young stars spans over 250 light-years at an estimated 3,800 light-year distance.

Rauf wrote: ↑Wed Feb 21, 2024 11:54 am

Astronut wrote: ↑Wed Feb 21, 2024 11:36 am What is the distance of the Seagull Nebula from earth?

https://apod.nasa.gov/apod/ap090327.html

Well, an old APOD mentioned this.

Dominated by the reddish glow of atomic hydrogen, the complex of cosmic gas and dust clouds with bright young stars spans over 250 light-years at an estimated 3,800 light-year distance.

I checked the Gaia parallaxes of a few of the blue stars in the Seagull Nebula. FN CMa does not, unfortunately, have a Gaia parallax (probably because the nebulosity next to it makes it hard for Gaia to get reliable measurements of its parallax), but another blue star in the Seagull Nebula, HD 53755, has a Gaia parallax of 0.9091±0.0441 milliarcseconds. Disregarding the uncertainly, this parallax gives a distance to HD 53755 of ~3,600 light-years.

Ann

Yes, the Seagull Nebula is "small" when compared to Barnard's Loop, but it's large compared to the Full Moon! Per the text, it's 5 times as wide:

Here's an image with some other "objects" annotated:

Also, what's that very bright area at the tip of the left wing (at the lower right in the image)?

johnnydeep wrote: ↑Wed Feb 21, 2024 1:56 pm Also, what's that very bright area at the tip of the left wing (at the lower right in the image)?

That's reflection nebula vdB 94. It surrounds B1II/III star HD HD 53623, which is hot enough to ionize a red emission nebula, but also "cool" enough (probably at least 20,000 K) not to blow all the surrounding dust away all too quickly. The star's blue light is reflected in the dusty reflection nebula, but its ultraviolet light ionizes a (pretty small) red emission nebula, Sharpless 297.


Ann

Ann wrote: ↑Wed Feb 21, 2024 2:35 pm

johnnydeep wrote: ↑Wed Feb 21, 2024 1:56 pm Also, what's that very bright area at the tip of the left wing (at the lower right in the image)?

That's reflection nebula vdB 94. It surrounds B1II/III star HD HD 53623, which is hot enough to ionize a red emission nebula, but also "cool" enough (probably at least 20,000 K) not to blow all the surrounding dust away all too quickly. The star's blue light is reflected in the dusty reflection nebula, but its ultraviolet light ionizes a (pretty small) red emission nebula, Sharpless 297.

Reflection nebula vdB 94. Credit: Velimir Popov and Emil Ivanov.

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Ann

Locutus76 wrote: ↑Wed Feb 21, 2024 10:51 am This gorgeous nebula always make me think of Godzilla’s Rodan, rather than a seagull.

Agreed - or a Diatryma's first ever flight...