Starship Asterisk*

The Helix Nebula from the VISTA Telescope

Explanation: Will our Sun look like this one day? The Helix Nebula is one of brightest and closest examples of a planetary nebula, a gas cloud created at the end of the life of a Sun-like star. The outer gasses of the star expelled into space appear from our vantage point as if we are looking down a helix. The remnant central stellar core, destined to become a white dwarf star, glows in light so energetic it causes the previously expelled gas to fluoresce. The Helix Nebula, given a technical designation of NGC 7293, lies about 700 light-years away towards the constellation of the Water Bearer (Aquarius) and spans about 2.5 light-years. The above picture was taken three colors on infrared light by the 4.1-meter Visible and Infrared Survey Telescope for Astronomy (VISTA) at the European Southern Observatory's Paranal Observatory in Chile. A close-up of the inner edge of the Helix Nebula shows complex gas knots of unknown origin.

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"glows in light so fluoresce" should be "glows in light so energetic it causes the previously expelled gas to fluoresce, but the missing bits are embedded in the "fluoresce" link- which is naturally broken as well.

It's interesting to see the different shapes of these nebulae. You could learn something about the structure of the star that died. We can look at the disc of Betelgeuse, for example and see bright patches and hazard a guess about what shape the nebula will be when it blows.

Thanks, Chris; I'll let TPTB know.

Does anybody know the approximate AGE of the star when it exploded?
Also, what was the estimated mass? And WHEN Earth time did the explosion occur? Did anyone record it?

Nice Picture.

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Just wondering: what happens to possible planets and their trajectories when the star explodes?

At the least, won't they be pushed out of their orbits? Incenderated? Broken apart if a solid planet? Blown away if a gaseous planet? All dependent upon the force of the blast and the distance of the planet from the exploding sun?

Will the Sun look like this one day? I realized at that point the concept of "day" will no longer be relevant (without our Sun!).

Gentle People:

If a Star is dying and in so doing is tearing itself apart., like all explosions Things are never cleanly obliturated. There are pieces. Those globuals are pieces of the star. Since the star is gas and gravity the Globuals are gas and gravity. This is a given and confirmed by the analysis. Now as to the origin?

In all the beautiful pictures and information on our own sun shown in APOD, with its mixed gases raging through its interior, haven't any of you astronomers noticed that if you have mixing and flows, you also have different densities AND different gravities. We see this on Earth, why is it not the same on/in the sun? These gravity pockets in the sun may be like rocks in the Earth, and actually Are. No matter how smal or how large, how slow or fast an explosion is, in an explosion, the light matter and the heavy matter move at different speeds (Newtonian Physics).

Globuals are pieces of the star, big pieces of dense Matter/Gravity that survived the final destruction of the star. They held together because gravity in the Globual was stronger that the force tearing the sun apart. But they are heavier than the gas and plasma, they are slower than the blat wave because of momentum, they are the slowest runners. The comet tail is the result of the still occuing radiation from that explosion moving faster than they are.

There is no mystery, all you need to do, is to look at it as an engineer. Somtimes comparitive observation beats math in explaination, I bet if you look at the helix with explosive dynamics in mind, the Math will catch up.

Captn Tommy

The Eye of Sauron.

Given the distance, 700 ly, and the estimate of when it took place (at the link to "inner edge"), 12,000 years ago, the supernova should have been seen, if not recorded in a cave or other long-lasting medium, about 13,000 years ago by Cro-magnon folk. Any archae-astronomers out there to help our queries?

These things are curiosities, indeed. I would expect that they would be generally spherical in shape rather than cylindrical or toroidal. We see bright stuff at the sides because we're looking on a line of sight tangential to the surface of the sphere. On a line of sight through the center, the material is too tenuous to be seen.

The star is a white dwarf, which means it first went through a red-giant stage and then simply collapsed without a lot of calamity like a supernova. The radiation we see is due to remnant heat; all nuclear reactions have ceased and the star is a slowly cooling cinder. Presumably, most close-in planets would have been consumed in the red-giant stage. Any outer gas giants would have had their atmospheres stripped away and only their rocky cores would remain.

leon.l7027@gmail.com wrote:Given the distance, 700 ly, and the estimate of when it took place (at the link to "inner edge"), 12,000 years ago, the supernova should have been seen, if not recorded in a cave or other long-lasting medium, about 13,000 years ago by Cro-magnon folk. Any archae-astronomers out there to help our queries?

This is a planetary nebula, not a supernova remnant. There was no supernova- the progenitor star was not massive enough for that.

OsmoA wrote:Just wondering: what happens to possible planets and their trajectories when the star explodes?

We see an image like this, and imagine a very violent event. But things are much less extreme in practice. At the end of its life, a star of low or intermediate mass sheds its outer layers in a series of fairly weak explosions. During the entire process, most of the star's mass is retained- a typical white dwarf masses perhaps 80% of its progenitor. So in reality, not all that much mass is lost, and the gas that is ejected is quite tenuous at typical planetary orbital radiuses. So nothing at all happens to planets from the expanding nebula- they certainly aren't blown outwards! However, the shift of some mass from the center of the system to a distributed cloud or shell around the system will have some effect. As the system evolves to one with a lower central mass, the planetary orbits must necessarily shift outwards somewhat, and the orbital periods increase. The shift in position, however, will neither be radical nor rapid.

Gee, Chris, you're making what would seem to an exciting happening, rather dull and mundane. Or is that only when it's not a super-nova? If it's a super-nova, THEN it gets exciting

Beyond wrote:Gee, Chris, you're making what would seem to an exciting happening, rather dull and mundane. Or is that only when it's not a super-nova? If it's a super-nova, THEN it gets exciting :?: :?:

Let's just say that the formation of a planetary nebula is a very low-energy event compared with a supernova. "Excitement" is in in the eye of the beholder.

I am definitaly " fluoresced ". Now for an ice cold one

Yeah, I KNOW what the real name of this nebula is... But most people I know, refer to it as "The Eye of God" And I just wanted to get that on record for posterity.

JamieWalker wrote:Yeah, I KNOW what the real name of this nebula is... But most people I know, refer to it as "The Eye of God" And I just wanted to get that on record for posterity.

I actually call it that too. It does not look to me like I am looking down a coil...

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Chris Peterson wrote:
Let's just say that the formation of a planetary nebula is a very low-energy event compared with a supernova.

"Excitement" is in in the eye of the beholder.

It looks EXACTLY like the EYE in Lord of the Rings ....and now all of us are "Ones who have seen the Eye."....rename it? Thanks APOD!

If a planetary nebula is spherical, how come we see it as cylindrical? Why doesn't the expanding gas coming directly towards us prevent us from seeing anything but a sphere of gas?

clintonbob wrote:If a planetary nebula is spherical, how come we see it as cylindrical? Why doesn't the expanding gas coming directly towards us prevent us from seeing anything but a sphere of gas?

http://en.wikipedia.org/wiki/Planetary_nebula#Morphology wrote:
<<Only about 20% of planetary nebulae are spherically symmetric . A wide variety of shapes exist with some very complex forms seen. Planetary nebulae are classified by different authors into: stellar, disk, ring, irregular, helical, bipolar, quadrupolar, and other types, although the majority of them belong to just three types: spherical, elliptical and bipolar. The nebulae of the last type show the strongest concentration to the galactic plane and their progenitors are therefore relatively young massive stars. On the other hand spherical nebulae are likely produced by the old stars similar to the Sun.

The huge variety of the shapes is partially the projection effect—the same nebula when viewed under different angles will look differently. Nevertheless the reason for the huge variety of physical shapes is not fully understood, but may be caused the gravitational interactions with companion stars if the central stars are double stars. Another possibility is that planets disrupt the flow of material away from the star as the nebula forms. It has been determined that the more massive stars produces more irregularly shaped nebulae. In January 2005, astronomers announced the first detection of magnetic fields around the central stars of two planetary nebulae, and hypothesised that the fields might be partly or wholly responsible for their remarkable shapes.>>

clintonbob wrote:If a planetary nebula is spherical, how come we see it as cylindrical? Why doesn't the expanding gas coming directly towards us prevent us from seeing anything but a sphere of gas?

Thanks