APOD: A Giant Squid in the Flying Bat (2015 Sep 11)

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APOD: A Giant Squid in the Flying Bat (2015 Sep 11)

Post by APOD Robot » Fri Sep 11, 2015 4:16 am

Image A Giant Squid in the Flying Bat

Explanation: Very faint but also very large on planet Earth's sky, a giant Squid Nebula cataloged as Ou4, and Sh2-129 also known as the Flying Bat Nebula, are both caught in this scene toward the royal constellation Cepheus. Composed with a total of 20 hours of broadband and narrowband data, the telescopic field of view is almost 4 degrees or 8 Full Moons across. Discovered in 2011 by French astro-imager Nicolas Outters, the Squid Nebula's alluring bipolar shape is distinguished here by the telltale blue-green emission from doubly ionized oxygen atoms. Though apparently completely surrounded by the reddish hydrogen emission region Sh2-129, the true distance and nature of the Squid Nebula have been difficult to determine. Still, a recent investigation suggests Ou4 really does lie within Sh2-129 some 2,300 light-years away. Consistent with that scenario, Ou4 would represent a spectacular outflow driven by a triple system of hot, massive stars, cataloged as HR8119, seen near the center of the nebula. If so, the truly giant Squid Nebula would physically be nearly 50 light-years across.

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Re: APOD: A Giant Squid in the Flying Bat (2015 Sep 11)

Post by Ann » Fri Sep 11, 2015 4:28 am

Oh, I really like this one! :D

I don't know if I've heard that Sh2-129 is called the Flying Bat Nebula, although I have heard that Ou4 is called the Squid Nebula. Batman and Aquaman, eh? Since Aquaman appears to be inside Batman, I can't help picturing a centaur sort of Batman, with Batman's head, upper torso and arms, and a female kangaroo's tail, hind legs and a belly with a pouch! This Bat-kanga is carrying Aquaman in his (her?) pouch!

I'm so fascinated by Ou4. To me this bipolar OIII nebula most definitely looks like a fantastic outflow from a multiple massive star system. Amazing!! Perhaps Eta Carina looked a little bit like this, right after its outburst in the 19th century. (Or not.) But although there appears to be another source of ionization in Sh2-129, I still think that both Batman and the Squid might be the children of the same massive star "Mama", HR 8119! :D

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Re: APOD: A Giant Squid in the Flying Bat (2015 Sep 11)

Post by Sternfreund » Fri Sep 11, 2015 8:42 am


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Re: APOD: A Giant Squid in the Flying Bat (2015 Sep 11)

Post by Boomer12k » Fri Sep 11, 2015 11:21 am

It looks more like a broken spear tip shoved into a heart, if you ask me...
But I see the Squid...not so much the bat....but other photos look more like a bat....somewhat...

I guess when the Cosmos needs The Batman....you get The Bat Nebula shining....On the Planet, Gotham, a certain Police Commissioner awaits. "Do,do,do,do,do,do,do,do.....BATMAN!!!!"

OR...the tip of the stake through Dracula's HEART???? :shock:

OR..."The Flaming Knife Nebula"...oh, well, I did not discover it, so I guess I don't get to name it....sigh....

Very good job...very nice image.

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Re: APOD: A Giant Squid in the Flying Bat (2015 Sep 11)

Post by starsurfer » Fri Sep 11, 2015 11:47 am

Ou 4 does look like an outflow and maybe it contributed to the shape of Sh2-129. No matter its nature, we can all agree it is a spectacular and unique object in the Milky Way! To think there are still many more things to be discovered!

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Re: APOD: A Giant Squid in the Flying Bat (2015 Sep 11)

Post by MarkBour » Fri Sep 11, 2015 3:32 pm

Boomer12k wrote: ...the tip of the stake through Dracula's HEART???? ... :---[===] *
Definitely would have been a great name for it.
Mark Goldfain

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Re: APOD: A Giant Squid in the Flying Bat (2015 Sep 11)

Post by Doink » Fri Sep 11, 2015 4:05 pm

MarkBour wrote:
Boomer12k wrote: ...the tip of the stake through Dracula's HEART???? ... :---[===] *
Definitely would have been a great name for it.
The "Skewered Vampire" Nebula?

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Re: APOD: A Giant Squid in the Flying Bat (2015 Sep 11)

Post by BMAONE23 » Fri Sep 11, 2015 5:03 pm

Batman and Aquaman...The new Dynamic Duo

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Re: APOD: A Giant Squid in the Flying Bat (2015 Sep 11)

Post by retro-galax » Sat Sep 12, 2015 2:17 am

Definatly A squid

:wink:

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Re: APOD: A Giant Squid in the Flying Bat (2015 Sep 11)

Post by David J Wilson » Sat Sep 12, 2015 3:40 am

My suggestion would be The Great Todger.

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Re: APOD: A Giant Squid in the Flying Bat (2015 Sep 11)

Post by DavidLeodis » Sat Sep 12, 2015 12:12 pm

I like the image. The short line of 3 colourful stars in the top left quadrant reminds me of Orion's belt. I would be grateful if someone could please explain in simple terms why some stars in the image are blue and others yellow.

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Re: APOD: A Giant Squid in the Flying Bat (2015 Sep 11)

Post by Ann » Sat Sep 12, 2015 3:00 pm

DavidLeodis wrote:I like the image. The short line of 3 colourful stars in the top left quadrant reminds me of Orion's belt. I would be grateful if someone could please explain in simple terms why some stars in the image are blue and others yellow.
The color of the stars reflect their temperature.

While the star is on the main sequence, like the Sun, its temperature depends on its mass.
Rick Gomez/Blend Images/Getty Images
Think of it like this. A low-mass star has to "lift" its own mass in order not to collapse. Since it doesn't weigh much, it doesn't have to produce a lot of energy in order to "hold itself up".
Chang W. Lee/The New York Times






A high-mass star, on the other hand, has to produce a lot of energy in order to counteract its own gravity.

The energy that own Sun has to produce in order to "hold itself up" gives it a temperature at its photospere (its "surface" temperature) of a bit less than 6,000K. The visible light from the Sun is the main source of light on the Earth, and our eyes have evolved so that we see the light from the Sun (i.e., daylight) as neutral, or "white". The Sun almost always looks quite yellow in illustrations, but that is not its true color.
The two Sunlike components of Alpha Centauri,
plus Proxima Centauri (arrowed). Photo: ESA
A star that is less massive than the Sun needs to produce less energy than the Sun in order to fight its own gravity. Unless such a star is highly evolved, it will be quite faint, much fainter than the Sun. Its light will also be much more yellow-orange than the light of the Sun. An example is the binary star 61 Cygni. Its brightest component is 0.153 times the luminosity of the Sun, and the fainter component is 0.085 times the solar luminosity. Both components would photograph as yellow. Much fainter still is the nearest star outside the solar system, Proxima Centauri. Proxima has a mass of only about 10% solar, and it shines, in visible light, only about one part in 15,000 as bright as the Sun. Its feeble light is orange.
Sirius and its (hot blue) white dwarf companion.
NASA, ESA and G. Bacon (STScI)
Stars more massive than the Sun have to fuse their hydrogen at a much faster rate to counter the inward pressure of their own mass. These stars also shine much brighter than the Sun. Sirius, the brightest-looking star in the sky, is about twice as massive as the Sun, but it shines about 23 times brighter. Its photosphere is also considerably hotter than the photosphere of the Sun, about 9,000K. Its light is far more dominated by shortwave, blue light than the Sun. In RGB images, Sirius will almost always look blue.
The Sun as a main sequence star and as a red giant at its maximum size.
A star that is on the main sequence, like the Sun, shines by fusing hydrogen to helium in its core. But a star's supply of core hydrogen is not infinite. After a star has used up its core hydrogen, its core will contract, releasing a lot of heat in the process, and at the same time its outer layers will expand. After a while the star will stabilize and start fusing its core helium into carbon and oxygen. But its outer layers will still be bloated and cool. The star is now a red giant. The temperature of the photosphere of the red giant will be cooler than the Sun's, about 4,000K versus ~6,000K for the Sun. The light of the red giant's photosphere will be far more dominated by red and yellow light than the photosphere of the Sun. A red giant will typically look yellow-orange in RGB images. So aren't red giants red? No, only certain extreme carbon stars are red.

Interestingly, you can see the colors of the stars for yourself using a good pair of binoculars, or better yet, a telescope. Watch out Capella, whose color is similar to the Sun's. Check out Vega right after you've looked at Capella, to see how much bluer it is. Then check out some red giants, from rather pale Pollux, which is only a bit yellower than Capella, to more strongly colored Dubhe and Arcturus. Then check out even more orange Betelgeuse and Antares, and go hunting for the even redder stars, like Mu Cephei. But the reddest-looking ones will be a few carbon stars like R Leporis.

Ann

EDIT: Uh, no. Sirius is not the brightest-looking star in the Earth's sky. That honor goes to the Sun. Obviously. :oops:
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Re: APOD: A Giant Squid in the Flying Bat (2015 Sep 11)

Post by DavidLeodis » Sun Sep 13, 2015 11:02 am

Thank you Ann for that very helpful reply :).

Talking of the colours (colors in US spelling :wink: ) of stars I find that the red ones are particularly obvious and even make it easier to quickly spot some constellations. As to planets I like the very obviously rusty red colour of Mars.

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Re: APOD: A Giant Squid in the Flying Bat (2015 Sep 11)

Post by Chris Peterson » Sun Sep 13, 2015 3:08 pm

DavidLeodis wrote:Thank you Ann for that very helpful reply :).

Talking of the colours (colors in US spelling :wink: ) of stars I find that the red ones are particularly obvious and even make it easier to quickly spot some constellations. As to planets I like the very obviously rusty red colour of Mars.
Yes, blue stars are very unsaturated, to the point that many people don't see them as blue at all. The nature of our eyes is such that the cool blackbodies are seen as much more saturated, hot ones as nearly white. The red, green, and blue bandpasses used for typical color sensors and color displays do very well for most terrestrial subjects, but are not well suited to most astronomical objects, presenting both narrowband sources and thermal sources in a way very different than we perceive them visually. So yes, red stars are much more obvious to most people than blue ones.
Chris

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Re: APOD: A Giant Squid in the Flying Bat (2015 Sep 11)

Post by starsurfer » Sun Sep 13, 2015 4:04 pm

Chris Peterson wrote:
DavidLeodis wrote:Thank you Ann for that very helpful reply :).

Talking of the colours (colors in US spelling :wink: ) of stars I find that the red ones are particularly obvious and even make it easier to quickly spot some constellations. As to planets I like the very obviously rusty red colour of Mars.
Yes, blue stars are very unsaturated, to the point that many people don't see them as blue at all. The nature of our eyes is such that the cool blackbodies are seen as much more saturated, hot ones as nearly white. The red, green, and blue bandpasses used for typical color sensors and color displays do very well for most terrestrial subjects, but are not well suited to most astronomical objects, presenting both narrowband sources and thermal sources in a way very different than we perceive them visually. So yes, red stars are much more obvious to most people than blue ones.
Carbon stars are a popular target for visual observers due to their intense red colour. Some double stars such as Albireo also display vivid colours.

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Re: APOD: A Giant Squid in the Flying Bat (2015 Sep 11)

Post by Chris Peterson » Sun Sep 13, 2015 4:29 pm

starsurfer wrote:Carbon stars are a popular target for visual observers due to their intense red colour. Some double stars such as Albireo also display vivid colours.
Indeed. But carbon stars are unique in that their color isn't determined by temperature.

I've noticed that quite a few first-time observers need to be prompted to see the blue component of Albireo as blue, even with the assist of a very yellow star right next to it.
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Re: APOD: A Giant Squid in the Flying Bat (2015 Sep 11)

Post by Ann » Sun Sep 13, 2015 6:08 pm

Chris wrote:
I've noticed that quite a few first-time observers need to be prompted to see the blue component of Albireo as blue, even with the assist of a very yellow star right next to it.
Image
I'm not impressed by Albireo. Its yellow component isn't very yellow, and its blue component isn't very blue.

My favorite small group of stars with contrasting colors is, hands down, 30 and 31 Cygni (where the orange component is also known as Omicron 2 Cygni), composed of a kind of turquoise A-type component, a yellow-orange K-type giant and a really blue B-type dwarf. The colors are fantastic.
Image
30 and 31 Cygni. Palomar Observatory/WikiSky.org.
Not Jerry's picture.
Jerry Lodriguss has taken a superb picture of this splendid stellar triplet. But Jerry doesn't want people to hotlink his images, which I can sympathize with. If you try, Jerry will notice what you are trying to do and disable your link. But here is a link to the page where Jerry shows two of his portraits of Omicron 1 and Omicron 2 Cygni. If the link stops working, I suggest you google Omicron 2 Cygni (or 30 and 31 Cygni) plus Jerry Lodriguss. His images are so much worth it!

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Re: APOD: A Giant Squid in the Flying Bat (2015 Sep 11)

Post by starsurfer » Tue Sep 15, 2015 1:51 pm

Ann wrote:
Chris wrote:
I've noticed that quite a few first-time observers need to be prompted to see the blue component of Albireo as blue, even with the assist of a very yellow star right next to it.
Image
I'm not impressed by Albireo. Its yellow component isn't very yellow, and its blue component isn't very blue.

My favorite small group of stars with contrasting colors is, hands down, 30 and 31 Cygni (where the orange component is also known as Omicron 2 Cygni), composed of a kind of turquoise A-type component, a yellow-orange K-type giant and a really blue B-type dwarf. The colors are fantastic.
Image
30 and 31 Cygni. Palomar Observatory/WikiSky.org.
Not Jerry's picture.
Jerry Lodriguss has taken a superb picture of this splendid stellar triplet. But Jerry doesn't want people to hotlink his images, which I can sympathize with. If you try, Jerry will notice what you are trying to do and disable your link. But here is a link to the page where Jerry shows two of his portraits of Omicron 1 and Omicron 2 Cygni. If the link stops working, I suggest you google Omicron 2 Cygni (or 30 and 31 Cygni) plus Jerry Lodriguss. His images are so much worth it!

Ann
Well everyone likes different things, you do have excellent taste in stars and deep sky objects. Near 30 Cygni is the star 32 Cygni, which is near the filamentary HII region LBN 331. Antonio Sánchez has an image of both of them!