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APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07)
Posted: Sun Aug 07, 2011 4:05 am
by APOD Robot
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.
[/b]
Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07
Posted: Sun Aug 07, 2011 5:42 am
by garry
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!
Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07
Posted: Sun Aug 07, 2011 6:08 am
by Ann
The only thing this planetary nebula reminds me of is an eye in space. I wonder who is looking...?
Ann
Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07
Posted: Sun Aug 07, 2011 6:37 am
by bto
how many times we gonna see this?
Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07
Posted: Sun Aug 07, 2011 6:46 am
by RPM
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?
Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07
Posted: Sun Aug 07, 2011 7:51 am
by Guest
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.
Re: An Hourglass Planetary Nebula (2011 Aug 07)
Posted: Sun Aug 07, 2011 11:22 am
by K1NS
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.
Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07
Posted: Sun Aug 07, 2011 12:23 pm
by orin stepanek
Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07
Posted: Sun Aug 07, 2011 12:50 pm
by BMAONE23
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?
Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07
Posted: Sun Aug 07, 2011 1:06 pm
by ErnieM
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?
Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07
Posted: Sun Aug 07, 2011 1:46 pm
by neufer
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:
http://asterisk.apod.com/viewtopic.php? ... 33#p131248
Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07
Posted: Sun Aug 07, 2011 5:11 pm
by ExplorerAtHeart
Would love to explore this stars planets, i am sure they are going through quite a time.
Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07
Posted: Sun Aug 07, 2011 7:13 pm
by NoelC
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.
-Noel
Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07
Posted: Sun Aug 07, 2011 7:55 pm
by bystander
That page links to another that has a tentative explanation:
bipolar outflow.
Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07
Posted: Sun Aug 07, 2011 8:49 pm
by PeterM
This one was already several times and even with the same text! Are you short of pictures?!!!
Regards,
Peter
Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07
Posted: Sun Aug 07, 2011 9:21 pm
by owlice
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?
A4: Yes. Many of our readers have been with us less than a year and are unaware of some really spectacular or important astronomy pictures. New information about old pictures is becoming available over the WWW. The text and links for rerun pictures will make use of this newly available information. So although the picture might be old, some of the text and links of each APOD will be new. Also, more web surfers have larger bandwidth connections, which allows us to post higher-resolution image files that can be transferred conveniently. Software to handle more sophisticated image file formats has also become more common, so the picture's size and/or format might be new. Lastly, rerunning APODs saves us time and helps us update our archive. In general, our rerun policy currently is to only rerun APODs more than one year old to keep the pictures relatively "new" to new APOD viewers. We will almost never rerun more than two pictures in any given week. So when you load the current APOD,it is still, most probably, a new picture.
Source:
http://apod.nasa.gov/apod/ap_faq.html
Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07
Posted: Sun Aug 07, 2011 10:42 pm
by Wolf Kotenberg
Remarcable resemblance to Eta Carinae. Which is older ?
Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07
Posted: Sun Aug 07, 2011 11:23 pm
by orin stepanek
Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07
Posted: Mon Aug 08, 2011 2:22 am
by Sam
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.)
Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07
Posted: Mon Aug 08, 2011 3:55 am
by Beyond
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.
Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07
Posted: Mon Aug 08, 2011 2:31 pm
by NoelC
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
-Noel
Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07
Posted: Wed Aug 10, 2011 6:26 pm
by Wolf kotenberg
Is it not the case SN1987 is also9 doing this ?
Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07
Posted: Wed Aug 10, 2011 6:55 pm
by Chris Peterson
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.
Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07
Posted: Wed Aug 10, 2011 10:22 pm
by NoelC
Wolf kotenberg wrote:Is it not the case SN1987 is also9 doing this ?
Tough to say...
- Hubble Composite of SN1987A
- SN1987A.jpg (40.72 KiB) Viewed 5003 times
-Noel
Re: APOD: MyCn18: An Hourglass Planetary Nebula (2011 Aug 07
Posted: Mon Aug 22, 2011 4:17 pm
by Merengues
Ann wrote:The only thing this planetary nebula reminds me of is an eye in space. I wonder who is looking...?
ha, you're right. it really resembles an eye. maybe it's superior creature looking at us?))
