APOD: The Seagull and the Duck (2018 Mar 16)

Comments and questions about the APOD on the main view screen.
User avatar
APOD Robot
Otto Posterman
Posts: 3481
Joined: Fri Dec 04, 2009 3:27 am

APOD: The Seagull and the Duck (2018 Mar 16)

Post by APOD Robot » Fri Mar 16, 2018 4:06 am

Image The Seagull and the Duck

Explanation: Seen as a seagull and a duck, these nebulae are not the only cosmic clouds to evoke images of flight. But both are winging their way across this broad celestial landscape, spanning almost 7 degrees across planet Earth's night sky toward the constellation Canis Major. The expansive Seagull (top center) is itself composed of two major cataloged emission nebulae. Brighter NGC 2327 forms the head with the more diffuse IC 2177 as the wings and body. Impressively, the Seagull's wingspan would correspond to about 250 light-years at the nebula's estimated distance of 3,800 light-years. At the lower right, the Duck appears much more compact and would span only about 50 light-years given its 15,000 light-year distance estimate. Blown by energetic winds from an extremely massive, hot star near its center, the Duck nebula is cataloged as NGC 2359. Of course, the Duck's thick body and winged appendages also lend it the slightly more dramatic popular moniker, Thor's Helmet.

<< Previous APOD This Day in APOD Next APOD >>

Boomer12k
:---[===] *
Posts: 2439
Joined: Sun Apr 22, 2007 12:07 am

Re: APOD: The Seagull and the Duck (2018 Mar 16)

Post by Boomer12k » Fri Mar 16, 2018 4:33 am

I don't know about you folks, but the bright "head of the seagull"...looks more like SCOOBY-DOO!!!! at least at a distance...

Maybe "The Duck"...is WEARING..."Thor's Helmet"....

Well, can't see them for a while... raining to beat the band tonight.
:---[===] *

starsurfer
Stellar Cartographer
Posts: 3445
Joined: Thu Mar 15, 2012 7:25 pm

Re: APOD: The Seagull and the Duck (2018 Mar 16)

Post by starsurfer » Fri Mar 16, 2018 9:16 am

I like the detail but the colour looks weird.

User avatar
Ann
4725 Å
Posts: 9367
Joined: Sat May 29, 2010 5:33 am

Re: APOD: The Seagull and the Duck (2018 Mar 16)

Post by Ann » Fri Mar 16, 2018 10:00 am

starsurfer wrote:
Fri Mar 16, 2018 9:16 am
I like the detail but the colour looks weird.
Agreed.

Ann
Color Commentator

Whiskybreath
Ensign
Posts: 16
Joined: Thu Dec 17, 2015 1:27 pm

Re: APOD: The Seagull and the Duck (2018 Mar 16)

Post by Whiskybreath » Fri Mar 16, 2018 11:51 am

Agree with Boomer12k above; instant impression is of a grinning Old English Sheepdog. Beautiful picture, though.

Sa Ji Tario

Re: APOD: The Seagull and the Duck (2018 Mar 16)

Post by Sa Ji Tario » Fri Mar 16, 2018 2:25 pm

It gives the impression that it is to shake the dust from among the feathers and it really is Scooby.-
On the other hand I do not find references of the Duck nebula, if of the Thor's Helmet

Bellerophon
Ensign
Posts: 24
Joined: Tue Apr 29, 2014 1:00 pm

Re: APOD: The Seagull and the Duck (2018 Mar 16)

Post by Bellerophon » Fri Mar 16, 2018 2:43 pm

If I try, I can make myself see a seagull. But no way do I see anything that remotely resembles a duck.

I expect tomorrow we'll find out there's a Leprechaun Nebula, and it'll look like a puddle of Guinness spilled on the bar.

User avatar
bystander
Apathetic Retiree
Posts: 18129
Joined: Mon Aug 28, 2006 2:06 pm
Location: Oklahoma

Re: APOD: The Seagull and the Duck (2018 Mar 16)

Post by bystander » Fri Mar 16, 2018 5:44 pm

The Duck Nebula (NGC 2359, aka Thor's Helmet) is in the lower right corner of the image.
APOD Robot wrote:
Fri Mar 16, 2018 4:06 am

At the lower right, the Duck appears much more compact and would span only about 50 light-years given its 15,000 light-year distance estimate. Blown by energetic winds from an extremely massive, hot star near its center, the Duck nebula is cataloged as NGC 2359. Of course, the Duck's thick body and winged appendages also lend it the slightly more dramatic popular moniker, Thor's Helmet.
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
— Garrison Keillor

Visual_Astronomer

Re: APOD: The Seagull and the Duck (2018 Mar 16)

Post by Visual_Astronomer » Fri Mar 16, 2018 7:51 pm

NGC 2359 is one of my favorite visual targets - with a narrow-band filter and the correct rotation, it really does look like a Viking helmet - horns and all. The Seagull, on the other hand, is difficult to make out - it is mostly very faint and quite extended.

Sa Ji Tario

Re: APOD: The Seagull and the Duck (2018 Mar 16)

Post by Sa Ji Tario » Sat Mar 17, 2018 2:19 am

For visual, with little imagination, the face of Thor appears and on the left the rasta is guessed

DAMGEM

Re: APOD: The Seagull and the Duck (2018 Mar 16)

Post by DAMGEM » Sun Mar 18, 2018 5:14 am

I like the image and can visualize their references.What caught my attention were the two spheres at top centre.
They seem so out of place. Perfect super-dense Ort cloud like objects.
Or could they be super novae remnants.

User avatar
Ann
4725 Å
Posts: 9367
Joined: Sat May 29, 2010 5:33 am

Re: APOD: The Seagull and the Duck (2018 Mar 16)

Post by Ann » Sun Mar 18, 2018 7:25 am

DAMGEM wrote:
Sun Mar 18, 2018 5:14 am
I like the image and can visualize their references.What caught my attention were the two spheres at top centre.
They seem so out of place. Perfect super-dense Ort cloud like objects.
Or could they be super novae remnants.
IC 2177, the Seagull Nebula. Note the purple "orbs" at top.
Photo: Strongmanmike. Large picture here.
The "two orbs" are reflection nebulas, not supernova remnants or Oort Cloud objects. I'm posting another picture of the Seagull Nebula here, because I find the colors of the APOD rather weird.

In the picture at left, you can clearly see the color difference between "the two orbs" at upper center-left and most of the Seagull Nebula itself. The Seagull Nebula is mostly magenta-pink. The color is a combination of red hydrogen alpha emission and blue-green hydrogen beta emission.

"The two orbs" at upper center-left look mostly purple. That is because the orbs are produced by normal but hot and bright stars, whose ultraviolet light ionizes hydrogen gas in the vicinity and makes it glow red, and their blue light is reflected in dust surrounding the stars. The stars in question are GU Canis Majoris (GU CMA, or HD 52721) and FZ Canis Majoris (FZ CMa, or HD 52942).

GU CMa is a star of spectral class B2Vne, hot enough to ionize some hydrogen gas and make it glow red, but cool enough to not to blow all the dust away, so that the dust can remain centered on the star and reflect its blue light. FZ CMa is a star of spectral class B3n. It is barely hot enough to ionize any hydrogen, but it could be that much of the ionizing of the gas around FZ CMa (and the gas around GU CMa) is actually done by the combined ultraviolet light of many hot stars in or near the Seagull Nebula.

I'd like to repeat that strongmanmike's picture makes the purple (red + blue) color of the "orbs" obvious, which in turn makes it easy for us to identify the "orbs" as nebulas made up of one emission (red) component and one reflection (blue) component. The "orb" centered on GU CMa is called vdB 88, and the "orb" centered on FZ CMa is called vdB 90. The orbs are named for their "reflection components", so they are named as reflection nebulas.

It is interesting that vdB 88 and vdB 90 are so round and so perfectly centered on the stars. They look like they are the products of some kind of outbursts of the stars themselves, where the gas and dust that was "cast off" during the outbursts have stayed centered on the stars, not unlike the cast-off shells of gas and dust in planetary nebulas. But GU CMa and FZ CMa are not scorchingly hot but "dead" little white dwarfs that have cast off all of their "outer atmospheres" and have stopped all energy-generating fusion processes. GU CMa and FZ CMa are normal stars, but hot and bright.

Ann
Color Commentator

starsurfer
Stellar Cartographer
Posts: 3445
Joined: Thu Mar 15, 2012 7:25 pm

Re: APOD: The Seagull and the Duck (2018 Mar 16)

Post by starsurfer » Sun Mar 18, 2018 10:17 am

DAMGEM wrote:
Sun Mar 18, 2018 5:14 am
I like the image and can visualize their references.What caught my attention were the two spheres at top centre.
They seem so out of place. Perfect super-dense Ort cloud like objects.
Or could they be super novae remnants.
Nah these are just emission nebulae.

Guest

Re: APOD: The Seagull and the Duck (2018 Mar 16)

Post by Guest » Sun Mar 18, 2018 1:43 pm

So Nice!

User avatar
Ann
4725 Å
Posts: 9367
Joined: Sat May 29, 2010 5:33 am

Re: APOD: The Seagull and the Duck (2018 Mar 16)

Post by Ann » Sun Mar 18, 2018 4:12 pm

starsurfer wrote:
Sun Mar 18, 2018 10:17 am
DAMGEM wrote:
Sun Mar 18, 2018 5:14 am
I like the image and can visualize their references.What caught my attention were the two spheres at top centre.
They seem so out of place. Perfect super-dense Ort cloud like objects.
Or could they be super novae remnants.
Nah these are just emission nebulae.
Emission and reflection nebulae. (Or nebulas, as Chris wants us to say.)

They are van den Bergh nebulas, so you can bet your boots that they have a significant reflection component!

Ann
Color Commentator

starsurfer
Stellar Cartographer
Posts: 3445
Joined: Thu Mar 15, 2012 7:25 pm

Re: APOD: The Seagull and the Duck (2018 Mar 16)

Post by starsurfer » Mon Mar 19, 2018 12:13 pm

Ann wrote:
Sun Mar 18, 2018 4:12 pm
starsurfer wrote:
Sun Mar 18, 2018 10:17 am
DAMGEM wrote:
Sun Mar 18, 2018 5:14 am
I like the image and can visualize their references.What caught my attention were the two spheres at top centre.
They seem so out of place. Perfect super-dense Ort cloud like objects.
Or could they be super novae remnants.
Nah these are just emission nebulae.
Emission and reflection nebulae. (Or nebulas, as Chris wants us to say.)

They are van den Bergh nebulas, so you can bet your boots that they have a significant reflection component!

Ann
I would say they're emission nebulae with reflection nebulae. The emission parts are in the Sharpless catalogue and the reflection in the vdB. Somebody should really do a closeup of them.

User avatar
Ann
4725 Å
Posts: 9367
Joined: Sat May 29, 2010 5:33 am

Re: APOD: The Seagull and the Duck (2018 Mar 16)

Post by Ann » Mon Mar 19, 2018 1:39 pm

starsurfer wrote:
Mon Mar 19, 2018 12:13 pm
Ann wrote:
Sun Mar 18, 2018 4:12 pm
starsurfer wrote:
Sun Mar 18, 2018 10:17 am

Nah these are just emission nebulae.
Emission and reflection nebulae. (Or nebulas, as Chris wants us to say.)

They are van den Bergh nebulas, so you can bet your boots that they have a significant reflection component!

Ann
I would say they're emission nebulae with reflection nebulae. The emission parts are in the Sharpless catalogue and the reflection in the vdB. Somebody should really do a closeup of them.
My software only tells me that they are van den Bergh reflection nebulas, vdB 88 and vdB 90.

What are their Sharpless designations?

Ann
Color Commentator

User avatar
neufer
Vacationer at Tralfamadore
Posts: 15805
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: APOD: The Seagull and the Duck (2018 Mar 16)

Post by neufer » Mon Mar 19, 2018 1:51 pm

Ann wrote:
Mon Mar 19, 2018 1:39 pm

My software only tells me that they are van den Bergh reflection nebulas, vdB 88 and vdB 90.

What are their Sharpless designations?
https://www.eso.org/public/news/eso1237/
Art Neuendorffer

User avatar
Ann
4725 Å
Posts: 9367
Joined: Sat May 29, 2010 5:33 am

Re: APOD: The Seagull and the Duck (2018 Mar 16)

Post by Ann » Mon Mar 19, 2018 2:22 pm

neufer wrote:
Mon Mar 19, 2018 1:51 pm
Ann wrote:
Mon Mar 19, 2018 1:39 pm

My software only tells me that they are van den Bergh reflection nebulas, vdB 88 and vdB 90.

What are their Sharpless designations?
https://www.eso.org/public/news/eso1237/
Thanks, Art, but Sharpless 2-292 is not the same nebula as vdB 88 or vdB 90.

Sharpless 2-292 is the "head" of the Seagull Nebula. It is located at upper center left in the image at left, centered on star V750 Monocerotis, or HD 53367. Sharpless 2-292 is (predominantly) an emission nebula.

van den Bergh 88 is located at upper center right in the image at left, centered on star GU Canis Majoris or HD 52721. van den Bergh 88 is a reflection nebula with an undeniable emission component.

van den Bergh 90 is located "right below" vdB 88 in the picture at left. vdB 90 is predominantly a reflection nebula.

I still don't know the designations of the Sharpless emission nebulas that coincide with reflection nebulas vdB 88 and vdB 90.

Ann
Color Commentator

starsurfer
Stellar Cartographer
Posts: 3445
Joined: Thu Mar 15, 2012 7:25 pm

Re: APOD: The Seagull and the Duck (2018 Mar 16)

Post by starsurfer » Wed Mar 21, 2018 9:48 am

Ann wrote:
Mon Mar 19, 2018 1:39 pm
starsurfer wrote:
Mon Mar 19, 2018 12:13 pm
Ann wrote:
Sun Mar 18, 2018 4:12 pm


Emission and reflection nebulae. (Or nebulas, as Chris wants us to say.)

They are van den Bergh nebulas, so you can bet your boots that they have a significant reflection component!

Ann
I would say they're emission nebulae with reflection nebulae. The emission parts are in the Sharpless catalogue and the reflection in the vdB. Somebody should really do a closeup of them.
My software only tells me that they are van den Bergh reflection nebulas, vdB 88 and vdB 90.

What are their Sharpless designations?

Ann
The one with vdB88 is Sh2-293 and the one with vdB90 is Sh2-295. I have found an image that shows them. You might like this image.

User avatar
Ann
4725 Å
Posts: 9367
Joined: Sat May 29, 2010 5:33 am

Re: APOD: The Seagull and the Duck (2018 Mar 16)

Post by Ann » Wed Mar 21, 2018 11:20 am

starsurfer wrote:
Wed Mar 21, 2018 9:48 am
Ann wrote:
Mon Mar 19, 2018 1:39 pm
starsurfer wrote:
Mon Mar 19, 2018 12:13 pm

I would say they're emission nebulae with reflection nebulae. The emission parts are in the Sharpless catalogue and the reflection in the vdB. Somebody should really do a closeup of them.
My software only tells me that they are van den Bergh reflection nebulas, vdB 88 and vdB 90.

What are their Sharpless designations?

Ann
The one with vdB88 is Sh2-293 and the one with vdB90 is Sh2-295. I have found an image that shows them. You might like this image.
Thanks! :D

I particularly like the second image. It really shows that vdB 90- Sh2-295 is mostly a reflection nebula, but vdB 88- Sh2-293 is mostly an emission nebula.

It makes sense that GU CMa should produce a brighter emission nebula than FZ CMa, because GU is a hotter, brighter star than FZ. Also GU CMa is a double system, and stars in close proximity can interact in such a way that the interaction in itself causes emission nebulosity. At least I think so!

Ann
Color Commentator