APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07)

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APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07)

Postby APOD Robot » Sun Aug 07, 2011 4:05 am

Image MyCn18: An Hourglass Planetary Nebula

Explanation: The sands of time are running out for the central star of this hourglass-shaped planetary nebula. With its nuclear fuel exhausted, this brief, spectacular, closing phase of a Sun-like star's life occurs as its outer layers are ejected - its core becoming a cooling, fading white dwarf. In 1995, astronomers used the Hubble Space Telescope (HST) to make a series of images of planetary nebulae, including the one above. Here, delicate rings of colorful glowing gas (nitrogen-red, hydrogen-green, and oxygen-blue) outline the tenuous walls of the hourglass. The unprecedented sharpness of the HST images has revealed surprising details of the nebula ejection process that are helping to resolve the outstanding mysteries of the complex shapes and symmetries of planetary nebulas.

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Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07

Postby garry » Sun Aug 07, 2011 5:42 am

If the outer layers are being ejected, why does it take on the shape of an hour glass? There must be other forces at work to allow the outer layers to be ejected not in a symmetrical shell formation but in an asymmetrical shape.
The other question is that even if you say that the layers are being ejected say along the poles, the two arms of the hour glass should be conical, not parallel. At a specific distance from the source star, the shape changes from conical to tubular. What forces would form the tubular shape at such a distance from the star when gravity would not be able to do it? Questions!
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Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07

Postby Ann » Sun Aug 07, 2011 6:08 am

The only thing this planetary nebula reminds me of is an eye in space. I wonder who is looking...? :wink:

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Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07

Postby bto » Sun Aug 07, 2011 6:37 am

how many times we gonna see this?
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Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07

Postby RPM » Sun Aug 07, 2011 6:46 am

I agree it looks like an eye. But if this pic was taken in 1995, can we not have Hubble take another now to compare the two, though it's been only 16 years, a mere blink in universe time?
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Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07

Postby Guest » Sun Aug 07, 2011 7:51 am

Yes!It really does resemble an eye!It is a beautiful picture of a unique planetary nebula. I do wish NASA would post updated pictures though.
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Re: An Hourglass Planetary Nebula (2011 Aug 07)

Postby K1NS » Sun Aug 07, 2011 11:22 am

It it not so much an hourglass but a DONUT. The parts of the donut that are towards us and behind the star aren't visible. I guess the distribution of ions must have been influenced by the star's donut-shaped magnetic field.
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Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07

Postby orin stepanek » Sun Aug 07, 2011 12:23 pm

viewtopic.php?f=9&t=20933
I think most planetary nebulae are fantastic! 8-)
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Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07

Postby BMAONE23 » Sun Aug 07, 2011 12:50 pm

Is there a way to determine the age of this star?
If it is a Sun Like star and our own star is approx 1/2 way through it's 10 billion year life span, is this star then 10 billion years old?
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Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07

Postby ErnieM » Sun Aug 07, 2011 1:06 pm

You are assuming that the ejection occurred in one big explosion similar to an exploding firework. What if there were multiple explosions at different cosmic time intervals. Would the star positions relative to its axis of rotation and its orbit when these explosions occurred have contribute to the shape of the nebula?
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Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07

Postby neufer » Sun Aug 07, 2011 1:46 pm

ErnieM wrote:
You are assuming that the ejection occurred in one big explosion similar to an exploding firework.
What if there were multiple explosions at different cosmic time intervals.

What if there was just a constant but strong stellar wind:
viewtopic.php?f=9&t=20933#p131248
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Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07

Postby ExplorerAtHeart » Sun Aug 07, 2011 5:11 pm

Would love to explore this stars planets, i am sure they are going through quite a time.
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Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07

Postby NoelC » Sun Aug 07, 2011 7:13 pm

Without soliciting discredited, far-fetched, or unfounded theories involving aliens or whatever...

How DO mainstream scientists explain the bipolar shapes of these nebulae? This isn't the only one - we've seen that the Ant Nebula, Eta Carinae, Red Spider Nebula, and other bipolar nebulae for example, have a similar hourglass or "two lobed" shape... There are others that happen to be aligned with us that may also be of a bipolar shape... The Ring Nebula and Helix Nebula among others come to mind.

There must be fundamental forces (magnetic? gravitational?) causing these shapes. I'd love to hear more about how they are explained.

We see a documentation from time to time, such as this page at wikipedia, that claim the exact processes aren't well known.

I'm sure I'm not the only one fascinated by the processes in stars that light up our universe with such beauty.

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Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07

Postby bystander » Sun Aug 07, 2011 7:55 pm

That page links to another that has a tentative explanation: bipolar outflow.
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Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07

Postby PeterM » Sun Aug 07, 2011 8:49 pm

:( This one was already several times and even with the same text! Are you short of pictures?!!!
Regards,
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Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07

Postby owlice » Sun Aug 07, 2011 9:21 pm

PeterM wrote::( This one was already several times and even with the same text! Are you short of pictures?!!!
Regards,
Peter

Q4: Have some APOD pictures been run more than once?
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Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07

Postby Wolf Kotenberg » Sun Aug 07, 2011 10:42 pm

Remarcable resemblance to Eta Carinae. Which is older ?
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Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07

Postby orin stepanek » Sun Aug 07, 2011 11:23 pm

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Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07

Postby Sam » Mon Aug 08, 2011 2:22 am

I discovered, from the hydrogen link, the origin of the phrase, "Oh the humanity!"

(I thought it was the from the unknown 20th century poet, Newman.)
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Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07

Postby Beyond » Mon Aug 08, 2011 3:55 am

Sam wrote:I discovered, from the hydrogen link, the origin of the phrase, "Oh the humanity!"

(I thought it was the from the unknown 20th century poet, Newman.)

WHEW!! For a minute there, i thought you meant Alfred E. Although it is spelled a little different.
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Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07

Postby NoelC » Mon Aug 08, 2011 2:31 pm

Sam wrote:I discovered, from the hydrogen link, the origin of the phrase, "Oh the humanity!"


Back when TV news people weren't just heartless talking heads.

http://www.youtube.com/watch?v=46bBWBG9r2o

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Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07

Postby Wolf kotenberg » Wed Aug 10, 2011 6:26 pm

Is it not the case SN1987 is also9 doing this ?
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Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07

Postby Chris Peterson » Wed Aug 10, 2011 6:55 pm

Wolf kotenberg wrote:Is it not the case SN1987 is also9 doing this ?

There are some superficial similarities in parts of each structure, but there are also significant differences, and the remnants have very different scales. I'd be cautious reading too much into the similarities, given the very different processes at work.
Chris

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Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07

Postby NoelC » Wed Aug 10, 2011 10:22 pm

Wolf kotenberg wrote:Is it not the case SN1987 is also9 doing this ?


Tough to say...

SN1987A.jpg


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Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07

Postby Merengues » Mon Aug 22, 2011 4:17 pm

Ann wrote:The only thing this planetary nebula reminds me of is an eye in space. I wonder who is looking...? :wink:

ha, you're right. it really resembles an eye. maybe it's superior creature looking at us?))
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