APOD: The Eskimo Nebula from Hubble and... (2013 Jul 30)

APOD Robot · Post by **APOD Robot** » Tue Jul 30, 2013 4:05 am

The Eskimo Nebula from Hubble and Chandra

Explanation: In 1787, astronomer William Herschel discovered the Eskimo Nebula. From the ground, NGC 2392 resembles a person's head surrounded by a parka hood. In 2000, the Hubble Space Telescope imaged the Eskimo Nebula in visible light, while the nebula was imaged in X-rays by the Chandra X-ray Observatory in 2007. The above combined visible-X ray image, with X-rays emitted by central hot gas and shown in pink, was released last week. From space, the nebula displays gas clouds so complex they are not fully understood. The Eskimo Nebula is clearly a planetary nebula, and the gas seen above composed the outer layers of a Sun-like star only 10,000 years ago. The inner filaments visible above are being ejected by strong wind of particles from the central star. The outer disk contains unusual light-year long orange filaments. The Eskimo Nebula spans about 1/3 of a light year and lies in our Milky Way Galaxy, about 3,000 light years distant, toward the constellation of the Twins (Gemini).

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bystander · Post by **bystander** » Tue Jul 30, 2013 4:06 am

http://asterisk.apod.com/viewtopic.php?t=31715

ro-star · Post by **ro-star** » Tue Jul 30, 2013 6:21 am

yes, I totally agree, the most appropriate name that comes to mind when looking at this nebula, is, clearly and obviously, "NGC 2392 - The Beating Heart Nebula"

Boomer12k · Post by **Boomer12k** » Tue Jul 30, 2013 7:18 am

Always such a cool picture.

:---[===] *

starsurfer · Post by **starsurfer** » Tue Jul 30, 2013 10:36 am

The orange filaments in the outer shell might be cometary knots like the ones in the Helix Nebula.

orin stepanek · Post by **orin stepanek** » Tue Jul 30, 2013 11:10 am

Neat photo of the Eskimo Nebula! +++

sonsofjob · Post by **sonsofjob** » Tue Jul 30, 2013 12:08 pm

In the accompanying comentary re: the Eskimo Nebula, the writer states that the orange filiments are approximately one light year long, and then states that the whole nebula is "1/3 of a light year across"? So, how is that possible?

Starwows · Post by **Starwows** » Tue Jul 30, 2013 1:06 pm

Isn't the outer disk part of the nebula? I don't understand these two statements together....

"The outer disk contains unusual light-year long orange filaments. The Eskimo Nebula spans about 1/3 of a light year "

Spiff · Post by **Spiff** » Tue Jul 30, 2013 2:29 pm

APOD Robot wrote: The Eskimo Nebula from Hubble and Chandra

while the nebula was imaged in X-rays by the Chandra X-ray Observatory in 2007. The above combined visible-X ray image, with X-rays emitted by central hot gas and shown in pink, was released last week.

Hmm, XRays? I guess I always assumed that planetary nebulae were relatively cool, low energy processes. The surfaces of old stars are relatively cool ... they tend to glow red which implies surface temperatures lower than our Sun (6000 Kelvin).

But XRay's imply very high temperature gas, super-energized. XRays are what you see from accretion gas right around the event horizon of a black hole. Really hot stuff.

Why would the gas emitted from a star in mass-loss phase be so energized?

Could this be a case of calibration or relative brightness? Perhaps the Chandra image is showing the really dim upper tail of the emission spectrum and then the compositing process is misleadingly showing the brightness of the XRay emissions as comparable to the brightness of the visual spectrum image?

Still, it seems surprising to me that mass-loss phase gases are significantly bright in XRay at all. Can anyone explain why there is so much XRay?

Scott

bystander · Post by **bystander** » Tue Jul 30, 2013 2:49 pm

Spiff wrote:Can anyone explain why there is so much XRay?

APOD Robot wrote:... The above combined visible-X ray image ...

[i]CXC: NGC 2392: A Beautiful End to a Star's Life[/i] wrote:...
The observations of NGC 2392 were part of a study of three planetary nebulas with hot gas in their center. The Chandra data show that NGC 2392 has unusually high levels of X-ray emission compared to the other two. This leads researchers to deduce that there is an unseen companion to the hot central star in NGC 2392. The interaction between a pair of binary stars could explain the elevated X-ray emission found there. Meanwhile, the fainter X-ray emission observed in the two other planetary nebulas in the sample — IC 418 and NGC 6826 — is likely produced by shock fronts (like sonic booms) in the wind from the central star...

Detection of Diffuse X-ray Emission from Planetary Nebulae with Nebular O VI - N. Ruiz et al
Astrophysical Journal 767(1) 35 (2013 Apr 10) DOI: 10.1088/0004-637X/767/1/35
arXiv.org > astro-ph > arXiv:1302.3886 > 15 Feb 2013

Ann · Post by **Ann** » Tue Jul 30, 2013 2:56 pm

Spiff wrote:
APOD Robot wrote: The Eskimo Nebula from Hubble and Chandra

while the nebula was imaged in X-rays by the Chandra X-ray Observatory in 2007. The above combined visible-X ray image, with X-rays emitted by central hot gas and shown in pink, was released last week.
Hmm, XRays? I guess I always assumed that planetary nebulae were relatively cool, low energy processes. The surfaces of old stars are relatively cool ... they tend to glow red which implies surface temperatures lower than our Sun (6000 Kelvin).

But XRay's imply very high temperature gas, super-energized. XRays are what you see from accretion gas right around the event horizon of a black hole. Really hot stuff.

Why would the gas emitted from a star in mass-loss phase be so energized?

Could this be a case of calibration or relative brightness? Perhaps the Chandra image is showing the really dim upper tail of the emission spectrum and then the compositing process is misleadingly showing the brightness of the XRay emissions as comparable to the brightness of the visual spectrum image?

Still, it seems surprising to me that mass-loss phase gases are significantly bright in XRay at all. Can anyone explain why there is so much XRay?

Scott

I'll let someone else comment on the X-rays, but I must point out that the central stars of planetary nebulae are very hot. They are the dead but hot exposed cores of stars that have lost all of their outer envelopes. The temperatures of central stars of planetary nebulae are typically 50,000 Kelvin or more.

Ann

Joe New · Post by **Joe New** » Tue Jul 30, 2013 3:01 pm

Why are "planetary" nebulae still called planetary? That really bugs me.

Roland · Post by **Roland** » Tue Jul 30, 2013 3:05 pm

if the filaments are a light year long that would make the span about 6 light years. Yet the text says 1/3 light year for the nebula. a little clarification would be good.

Spif · Post by **Spif** » Tue Jul 30, 2013 3:08 pm

Joe New wrote:Why are "planetary" nebulae still called planetary? That really bugs me.

Me too! If "they" are going to go to so much trouble to alter terminology and thereby demote Pluto, they might as well stop using blatantly misleading ill-educated terms like this.

How about a nice complicated academic-sounding 4 syllable latin word or something?

-s

Spif · Post by **Spif** » Tue Jul 30, 2013 3:46 pm

Spif wrote:
Joe New wrote:Why are "planetary" nebulae still called planetary? That really bugs me.
How about a nice complicated academic-sounding 4 syllable latin word or something?

Ok, I got it, let's all start calling it a "Stella Mortis" nebula.

Maybe it will catch on

-s

ps: My apologies, in advance, to anyone actually named "Stella Mortis". No offense was intended or implied. Unless, of course, you actually like the idea of some nebulae being named after you. In which case, I should get the credit.

Qimmiq Whisperer · Post by **Qimmiq Whisperer** » Tue Jul 30, 2013 4:01 pm

Spif wrote:
Ok, I got it, let's all start calling it a "Stella Mortis" nebula.

http://www.youtube.com/watch?v=s1_dgLdic7M#at=19

neufer · Post by **neufer** » Tue Jul 30, 2013 4:18 pm

Click to play embedded YouTube video.

sonsofjob wrote:
In the accompanying comentary re: the Eskimo Nebula, the writer states that the orange filaments are approximately one light year long, and then states that the whole nebula is "1/3 of a light year across"? So, how is that possible?

The "cometary" commentary is wrong.

The inner nebula has a radius of about 1/3 of a light year.

The orange filaments extend out to a radius of about 1 light year.

Beyond · Post by **Beyond** » Tue Jul 30, 2013 4:43 pm

Thanks, neufer. Too bad you didn't post the video earlier, as it would have cut down on the particle usage in this thread.

Anthony Barreiro · Post by **Anthony Barreiro** » Tue Jul 30, 2013 6:49 pm

Joe New wrote:Why are "planetary" nebulae still called planetary? That really bugs me.

Planetary nebulae, especially those that are relatively compact and bright, really do look remarkably like Uranus or Neptune through a moderately-sized telescope. Even with more diffuse planetary nebulae, you can imagine that the gas is falling inward to form a planet (the original theory) rather than being blown outward by the solar wind of a dying star.

Personally I hope we will keep the name, because it gives amateur astronomers at public star parties a chance to tell visitors about William Herschel, the first individual to discover a planet (Uranus), and the guy who tried to push his luck by coining the term "planetary nebula." And then the visitors walk away knowing that "of course a planetary nebula doesn't have anything to do with a planet, that's just a historical term ... ."

KarelVreeburg · Post by **KarelVreeburg** » Tue Jul 30, 2013 9:45 pm

I don't understand, You must be all qualified professionals,….. Seeing this Nebula and comparing it to others , this must be a Hour glass nebula. an ending system , not a planet forming system. Look carefully and you see the hour glass. In 3D it is huge more deep then wide. See and you know. It is dying, not forming (yet) Karel

Anthony Barreiro · Post by **Anthony Barreiro** » Tue Jul 30, 2013 10:19 pm

KarelVreeburg wrote:I don't understand, You must be all qualified professionals,….. Seeing this Nebula and comparing it to others , this must be a Hour glass nebula. an ending system , not a planet forming system. Look carefully and you see the hour glass. In 3D it is huge more deep then wide. See and you know. It is dying, not forming (yet) Karel

Karel, yes, you're right about planetary nebulae (but wrong about the professional qualifications of many of the participants in this forum). The term "planetary nebula" was coined by William Herschel in the late 18th century. Herschel became an international rock star when he discovered the planet Uranus in 1781. Herschel's newfound fame and fortune went to his head and he started seeing Uranus-like objects everywhere!

Uranus through an eight-inch aperture telescope

NGC7662, the Blue Snowball nebula, through an eight-inch aperture telescope

When Herschel saw nebulae that had bright roundish cores and more diffuse stuff around those cores, his wishful thinking led him to conclude that the diffuse stuff was condensing to form a new planet.

M27, the Dumbbell nebula, through a 14-inch telescope

Fortunately the scientific method gives us the opportunity to question and test previous assumptions, and over the past 200 years we have developed a much better understanding of what these odd-looking things are and how they form.

Regarding Starship Asterisk, some of our most active participants are professional scientists or engineers. But many of us are only interested amateurs. And some of us just like to look at pretty pictures and learn new things about the universe.

Starship Asterisk*

APOD: The Eskimo Nebula from Hubble and... (2013 Jul 30)

APOD: The Eskimo Nebula from Hubble and... (2013 Jul 30)

Re: APOD: The Eskimo Nebula from Hubble and... (2013 Jul 30)

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Re: APOD: The Eskimo Nebula from Hubble and... (2013 Jul 30)

Re: APOD: The Eskimo Nebula from Hubble and... (2013 Jul 30)

Re: APOD: The Eskimo Nebula from Hubble and... (2013 Jul 30)

Eskimo Nebula

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XRays?

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Re: APOD: The Eskimo Nebula from Hubble and... (2013 Jul 30)

Re: APOD: The Eskimo Nebula from Hubble and... (2013 Jul 30)

Re: APOD: The Eskimo Nebula from Hubble and... (2013 Jul 30)

Re: APOD: The Eskimo Nebula from Hubble and... (2013 Jul 30)

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Re: APOD: The Eskimo Nebula from Hubble and... (2013 Jul 30)

Re: APOD: The Eskimo Nebula from Hubble and... (2013 Jul 30)

Re: APOD: The Eskimo Nebula from Hubble and... (2013 Jul 30)

Re: APOD: The Eskimo Nebula from Hubble and... (2013 Jul 30)