APOD: NGC 7293: The Helix Nebula (2011 Jan 08)

[APOD Robot]

NGC 7293: The Helix Nebula

Explanation: A mere seven hundred light years from Earth, in the constellation Aquarius, a sun-like star is dying. Its last few thousand years have produced the Helix Nebula (NGC 7293), a well studied and nearby example of a Planetary Nebula, typical of this final phase of stellar evolution. A total of 10 hours of exposure time have gone in to creating this remarkably deep view of the nebula. It shows details of the Helix's brighter inner region, about 3 light-years across, but also follows fainter outer halo features that give the nebula a span of well over six light-years. The white dot at the Helix's center is this Planetary Nebula's hot, central star. A simple looking nebula at first glance, the Helix is now understood to have a surprisingly complex geometry.

<< Previous APOD

Discuss Any APOD

Next APOD >>

[/b]

[orin stepanek]

I have gotten emails on occasion of the Helix Nebula calling it God's eye. It is a beautiful nebula as most nebulae are.
http://hubblesite.org/newscenter/archiv ... web_print/

[neufer]

Hubble's Helix with Annotated Features http://asterisk.apod.com/viewtopic.php?f=9&t=17903 http://apod.nasa.gov/apod/ap091231.html

---

<<Karl Ludwig Harding (September 29, 1765 – August 31, 1834) was a German astronomer notable for having discovered the asteroid 3 Juno (1804), the Helix Nebula (c. 1824) and three comets.

Harding was born in Lauenburg. He was educated at the University of Göttingen, where he studied theology. In 1796 Johann Hieronymus Schröter hired Harding as a tutor for his son. Schröter was an enthusiastic astronomer, and Harding was soon appointed observer and inspector in his observatory.

In 1804, Harding discovered Juno at Schröter's observatory. He then went to Göttingen to assist Carl Friedrich Gauss. There he was professor of astronomy.

The crater Harding on the Moon is named after him, and so is the asteroid 2003 Harding.>>

[NoelC]

Congratulations once again to Ed Henry for a beautiful APOD.

I think it's a testment to Ed's skill and care and to the advancements in astroimaging that his image can be so directly compared to a Hubble shot (thanks, Neufer). People often have trouble even recognizing the same objects in ground-based imagery when compared with a Hubble image.

-Noel

[zloq]

I can't see any info on the equipment used or the exposures. The site associated with the image just describes a 10" f/6.3 lx200 with reducer - but it's not clear that is what took this image. Normally apod images are provided with equipment and exposure details - at least I prefer them to include that info somewhere.

zloq

[zloq]

Oh - there it is. TMB 152, ten hours. It is in the link in the apod text, but not when you click on the image itself. TMB 152 makes much more sense than 10" f/6.3 lx200 with reducer.

zloq

[biddie67]

Only 700 LY away ... so close yet so far away ... I wonder if I could spot this nebula with just my binoculars ...

The graphic of the features of the nebula was most interesting and very helpful in comparing details between the APOD photo and the graphic. Thanks for your fine work, Ed Henry!!

[Céline Richard]

The "inner disk" (thank you Neufer!) of the Helix Nebula looks like a big blue eye open in the night of the Universe.
It is very impressing!

Céline

[Joe Stieber]

Only 700 LY away ... so close yet so far away ... I wonder if I could spot this nebula with just my binoculars ...

From a reasonably dark site, the Helix is not difficult to spot in binoculars. However, it's just a dim hazy patch (with no real color), so you need to know where to look. I swoop about 10 degrees northwest of Fomalhaut to Upsilon Aquarii (which is at the end of a distinctive row of three stars), then shift west slightly more than degree, and it's centered. We're nearing the end of the season for the Helix though. At 40 degrees north latitude, it's now setting around 8 pm local time.

[neufer]

Current issues in planetary nebula studies

<<A long standing problem in the study of planetary nebulae is that in most cases, their distances are very poorly determined. For the nearest planetary nebulae, it is possible to determine distances by measuring their expansion parallax. High resolution observations taken several years apart will show the expansion of the nebula perpendicular to the line of sight, while spectroscopic observations of the Doppler shift will reveal the velocity of expansion in the line of sight. Comparing the angular expansion with the derived velocity of expansion will reveal the distance to the nebula.

The issue of how such a diverse range of nebular shapes can be produced is a controversial topic. It is believed that interactions between material moving away from the star at different speeds gives rise to most observed shapes. However, some astronomers believe that double central stars must be responsible for the more complex and extreme planetary nebulae. Several planetary nebulae have been shown to contain strong magnetic fields, something which has been hypothesized by Grigor Gurzadyan in the 1960s. Magnetic interactions with ionized gas could be responsible for shaping some planetary nebulae.

There are two methods of determining metal abundances in nebulae. These rely on different types of spectral lines—recombination lines and collisionally excited lines. Large discrepancies are sometimes seen between the results derived from the two methods. Some astronomers explain this by presence of small temperature fluctuations within planetary nebulae; others claim that the discrepancies are too large to be explained by temperature effects, and hypothesize the existence of cold knots containing very little hydrogen to explain the observations. However, no such knots have yet been observed.>>

[Pentaxian]

The issue of how such a diverse range of nebular shapes can be produced is a controversial topic.

Not knowing the term to look for, I'd like to ask a newbie question of the group.

What I refer to in this beautiful image of the Helix Nebula as "blobs" that inhabit the inner ring (approx), and appear as globular entities with a trailing "robe" in their shadows, what are they called, and what do they consist of? >o

I've of course seen them in many images that are similar, or not, such as in the "horsehead nebula".

[Dacio]

The issue of how such a diverse range of nebular shapes can be produced is a controversial topic.

What I refer to in this beautiful image of the Helix Nebula as "blobs" that inhabit the inner ring (approx), and appear as globular entities with a trailing "robe" in their shadows, what are they called, and what do they consist of? >o I've of course seen them in many images that are similar, or not, such as in the "horsehead nebula".

Pentaxian, here is a video that I uploaded that talks about the blobs you mention, they are called "cometary knots" and they remain a mystery. I painted The Helix on 2009, check it out here


[youtube]http://www.youtube.com/watch?v=usHgvTff ... r_embedded[/youtube]

[Céline Richard]

Thank you Dacio for posting the video the "Hubble Minute"

I painted The Helix on 2009, check it out here

That's wonderful
From above, the Helix Nebula looks like a little to the interior of the Yellowstone's volcano, so beautiful!

I prefer your Swann Nebula's painting, and i love both the Moon's painting ("Crescent Desolation") and Jupiter's red spot's painting ("Thundering Jove").

I hope you will keep painting this year!!!

Céline

PS: the picture is from Dacio's website http://thecosmosgallery.com/mypaintings/helix-nebula/
I hope i can post your paintings (if not, i can remove it anytime, just ask it).

[Dacio]

Thank you Dacio for posting the video the "Hubble Minute"
From above, the Helix Nebula looks like a little to the interior of the Yellowstone's volcano, so beautiful!

Bonjour Céline,
Thank you for posting my paintings, that was so nice of you.
You are right, the Helix nebula does look like something out of Yellowstone, and I know what you are referring to:The Grand Prismatic Spring.
If I believed in psychics (and I don't), I would think you are one because I was working last week on a draft for a painting of "The Grand Prismatic Spring".

Hope you can join me on facebook: http://www.facebook.com/TheCosmosGallery

cheers,
-Dacio

[Céline Richard]

You are right, the Helix nebula does look like something out of Yellowstone, and I know what you are referring to:The Grand Prismatic Spring.
If I believed in psychics (and I don't), I would think you are one because I was working last week on a draft for a painting of "The Grand Prismatic Spring".

Bonjour Dacio

Yes, it is exactly to what i was trying to refer to, the Grand Prismatic Spring The Universe is very rich in analogy, or (and) human thought has a natural propensity to make analogy, comparisons and symbols.
Cheers,

Céline

[jkeller21]

The Helix Nebula looks like an eye. The pupil of this "eye" is the blueish greenish middle part of the nebula. The white part of the "eye" is the pink surrounding it in a cloudlike flurry. The nebula looks alone in the vastness of space.