APOD: Planetary Nebula Mz3: The Ant Nebula (2015 Apr 26)

Comments and questions about the APOD on the main view screen.
User avatar
APOD Robot
Otto Posterman
Posts: 2998
Joined: Fri Dec 04, 2009 3:27 am

APOD: Planetary Nebula Mz3: The Ant Nebula (2015 Apr 26)

Postby APOD Robot » Sun Apr 26, 2015 4:09 am

Image Planetary Nebula Mz3: The Ant Nebula

Explanation: Why isn't this ant a big sphere? Planetary nebula Mz3 is being cast off by a star similar to our Sun that is, surely, round. Why then would the gas that is streaming away create an ant-shaped nebula that is distinctly not round? Clues might include the high 1000-kilometer per second speed of the expelled gas, the light-year long length of the structure, and the magnetism of the star visible above at the nebula's center. One possible answer is that Mz3 is hiding a second, dimmer star that orbits close in to the bright star. A competing hypothesis holds that the central star's own spin and magnetic field are channeling the gas. Since the central star appears to be so similar to our own Sun, astronomers hope that increased understanding of the history of this giant space ant can provide useful insight into the likely future of our own Sun and Earth.

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

starsurfer
Stellar Cartographer
Posts: 2846
Joined: Thu Mar 15, 2012 7:25 pm

Re: APOD: Planetary Nebula Mz3: The Ant Nebula (2015 Apr 26)

Postby starsurfer » Sun Apr 26, 2015 11:17 am

This is one of the best HST images of many planetary nebulae (more than 3000 are now known) in the Milky Way. Although it is false colour, I don't mind as it looks so pretty! A true colour image would show it to be red and pink.

This is probably the most well known of the few planetary nebulae discovered by the astronomer Donald Menzel. Mz 1 and Mz 2 (along with Mz 3 are in the constellation Norma) also have nice structure but have been photographed much less.

JeffKLass

Re: APOD: Planetary Nebula Mz3: The Ant Nebula (2015 Apr 26)

Postby JeffKLass » Sun Apr 26, 2015 11:25 am

If this planetary nebula had by chance been turned 90˚ and thus inline with our line of site we'd see it as wildly spherical and have no idea that it is bi-nodular. Accordingly, one wonders which of the spherical planetary nebulae that we can see are in reality bi-nodular. Would it even be possible to ascertain hidden bi-nodularity in spherical planetary nebulae?

bub4280

Re: APOD: Planetary Nebula Mz3: The Ant Nebula (2015 Apr 26)

Postby bub4280 » Sun Apr 26, 2015 1:11 pm

Astronomers should study fireworks. There is a ground-spinner called a "chrysanthemum" that forms Lissajous figures in flame as it spins and twists in 3 dimensions. Looks similar to this.

Boomer12k
:---[===] *
Posts: 2090
Joined: Sun Apr 22, 2007 12:07 am

Re: APOD: Planetary Nebula Mz3: The Ant Nebula (2015 Apr 26)

Postby Boomer12k » Sun Apr 26, 2015 3:00 pm

We are soooooooo toast.....


:---(===) *

Boomer12k
:---[===] *
Posts: 2090
Joined: Sun Apr 22, 2007 12:07 am

Re: APOD: Planetary Nebula Mz3: The Ant Nebula (2015 Apr 26)

Postby Boomer12k » Sun Apr 26, 2015 3:02 pm

Question.... Is it through yet? Or still near the beginning?

:---(===) *

hoohaw

Re: APOD: Planetary Nebula Mz3: The Ant Nebula (2015 Apr 26)

Postby hoohaw » Sun Apr 26, 2015 3:06 pm

starsurfer wrote:... discovered by the astronomer Donald Menzel.

Menzel is famous for not believing in UFOs ... and for not believing in black holes, either: http://adsabs.harvard.edu/abs/1975MSRSL...9..343M

User avatar
Chris Peterson
Abominable Snowman
Posts: 13287
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Planetary Nebula Mz3: The Ant Nebula (2015 Apr 26)

Postby Chris Peterson » Sun Apr 26, 2015 3:20 pm

starsurfer wrote:Although it is false colour, I don't mind as it looks so pretty! A true colour image would show it to be red and pink.

True color images show just about everything to be shades of pink, because of the way hydrogen dominates. About all we see is H alpha and continuum light, with maybe a little green from oxygen. That's why we don't see so many natural color images from HST. They hide too much information. To really see and understand something, we usually need to look at narrowband emissions. That this happens to also be pretty is just an added bonus!
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

User avatar
Ann
4725 Å
Posts: 8471
Joined: Sat May 29, 2010 5:33 am

Re: APOD: Planetary Nebula Mz3: The Ant Nebula (2015 Apr 26)

Postby Ann » Sun Apr 26, 2015 11:13 pm

Chris Peterson wrote:
starsurfer wrote:Although it is false colour, I don't mind as it looks so pretty! A true colour image would show it to be red and pink.

True color images show just about everything to be shades of pink, because of the way hydrogen dominates. About all we see is H alpha and continuum light, with maybe a little green from oxygen. That's why we don't see so many natural color images from HST. They hide too much information. To really see and understand something, we usually need to look at narrowband emissions. That this happens to also be pretty is just an added bonus!


Some planetaries look very green (or blue, or turquoise) in RGB images. In other words, some planetaries are dominated by OIII emission. The fine RGB image of the Ant Nebula (thanks for the link, starsurfer!) shows it to be totally dominated by hydrogen, and that is not a given at all when it comes to planetaries.

Does anyone have any sort of explanation as to why some planetaries are so dominated by oxygen and others so dominated by hydrogen? I can't help thinking of the extragalactic objects similar to Hanny's Voorwerp, which glow green from OIII, and which have been ionized by energetic quasar jets.

(And by the way... I find the pink RGB image of the Ant Nebula, set among differently-colored stars, more beautiful than the HST image. But that is just a matter of taste.)

Ann
Color Commentator

starsurfer
Stellar Cartographer
Posts: 2846
Joined: Thu Mar 15, 2012 7:25 pm

Re: APOD: Planetary Nebula Mz3: The Ant Nebula (2015 Apr 26)

Postby starsurfer » Mon Apr 27, 2015 11:40 am

Ann wrote:
Chris Peterson wrote:
starsurfer wrote:Although it is false colour, I don't mind as it looks so pretty! A true colour image would show it to be red and pink.

True color images show just about everything to be shades of pink, because of the way hydrogen dominates. About all we see is H alpha and continuum light, with maybe a little green from oxygen. That's why we don't see so many natural color images from HST. They hide too much information. To really see and understand something, we usually need to look at narrowband emissions. That this happens to also be pretty is just an added bonus!


Some planetaries look very green (or blue, or turquoise) in RGB images. In other words, some planetaries are dominated by OIII emission. The fine RGB image of the Ant Nebula (thanks for the link, starsurfer!) shows it to be totally dominated by hydrogen, and that is not a given at all when it comes to planetaries.

Does anyone have any sort of explanation as to why some planetaries are so dominated by oxygen and others so dominated by hydrogen? I can't help thinking of the extragalactic objects similar to Hanny's Voorwerp, which glow green from OIII, and which have been ionized by energetic quasar jets.

(And by the way... I find the pink RGB image of the Ant Nebula, set among differently-colored stars, more beautiful than the HST image. But that is just a matter of taste.)

Ann

And don't forget that some planetary nebulae are dominated by NII emission. The most common tracer used for planetary nebulae is OIII, I don't know the exact percentage of all known planetary nebulae that are predominantly OIII but hydrogen only planetary nebulae are rare. The Ant Nebula has a little OIII emission as well.

I don't know what processes determine whether a planetary nebula will be dominated by hydrogen or oxygen but I assume it is related to the overall chemical composition of the progenitor star. There are lots of planetary nebula related books I would love to read but finding the time is a problem unfortunately.

I hope to see more detailed amateur "natural" colour images of more unphotographed southern planetary nebulae!
Last edited by starsurfer on Mon Apr 27, 2015 11:44 am, edited 1 time in total.

starsurfer
Stellar Cartographer
Posts: 2846
Joined: Thu Mar 15, 2012 7:25 pm

Re: APOD: Planetary Nebula Mz3: The Ant Nebula (2015 Apr 26)

Postby starsurfer » Mon Apr 27, 2015 11:43 am

Chris Peterson wrote:
starsurfer wrote:Although it is false colour, I don't mind as it looks so pretty! A true colour image would show it to be red and pink.

True color images show just about everything to be shades of pink, because of the way hydrogen dominates. About all we see is H alpha and continuum light, with maybe a little green from oxygen. That's why we don't see so many natural color images from HST. They hide too much information. To really see and understand something, we usually need to look at narrowband emissions. That this happens to also be pretty is just an added bonus!

I think generally astronomers study the information of an object from looking at the different narrowband emissions separately, it is a lot easier to distinguish the distribution of the particular Ha and OIII emission associated with a particular object. I think the only time you see all wavelengths together is when they are combined to produce an aesthetic image, which I think is also equally important as it can inspire people to do further research and study and generally be awed at the incredibleness of the universe.

User avatar
Chris Peterson
Abominable Snowman
Posts: 13287
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Planetary Nebula Mz3: The Ant Nebula (2015 Apr 26)

Postby Chris Peterson » Mon Apr 27, 2015 2:19 pm

Ann wrote:Does anyone have any sort of explanation as to why some planetaries are so dominated by oxygen and others so dominated by hydrogen?

There are different reasons. In some cases, the spatial distribution of gas is real- shells blown off at different times can have different compositions (because layers of the parent star have different compositions). Also, processes in the nebula can cause some separation by mass. In some cases, however, the distribution is illusory. Because of the different ionization potentials of different atoms, some areas that are actually mixed can show just one emission line. In most nebulas, you probably have a little of both effects going on.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

User avatar
Chris Peterson
Abominable Snowman
Posts: 13287
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Planetary Nebula Mz3: The Ant Nebula (2015 Apr 26)

Postby Chris Peterson » Mon Apr 27, 2015 2:24 pm

starsurfer wrote:I think generally astronomers study the information of an object from looking at the different narrowband emissions separately, it is a lot easier to distinguish the distribution of the particular Ha and OIII emission associated with a particular object.

Channels are combined for scientific purposes, as well. Using narrowband data lets us map out specific elements (or in some cases, complex molecules). Some of these are indistinguishable in broadband images (the very important components of nitrogen, hydrogen, and sulfur all emit in the red, and are indistinguishable in natural color images). Narrowband images are combined in order to look at the broad structure of many objects, which is not always fully visible in any single channel (when, for example, the different components are mixed but not uniformly ionized).
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

starsurfer
Stellar Cartographer
Posts: 2846
Joined: Thu Mar 15, 2012 7:25 pm

Re: APOD: Planetary Nebula Mz3: The Ant Nebula (2015 Apr 26)

Postby starsurfer » Tue Apr 28, 2015 12:32 pm

Chris Peterson wrote:
starsurfer wrote:I think generally astronomers study the information of an object from looking at the different narrowband emissions separately, it is a lot easier to distinguish the distribution of the particular Ha and OIII emission associated with a particular object.

Channels are combined for scientific purposes, as well. Using narrowband data lets us map out specific elements (or in some cases, complex molecules). Some of these are indistinguishable in broadband images (the very important components of nitrogen, hydrogen, and sulfur all emit in the red, and are indistinguishable in natural color images). Narrowband images are combined in order to look at the broad structure of many objects, which is not always fully visible in any single channel (when, for example, the different components are mixed but not uniformly ionized).

Thanks for your detailed response! I like it when scientific papers present the separate Ha and OIII structure of objects, it's nice to compare.


Return to “The Bridge: Discuss an Astronomy Picture of the Day”

Who is online

Users browsing this forum: Semrush [Bot] and 1 guest