Image of the Day: Odd Objects of the Helix Nebula

 

             

 

The Helix Nebula is one of the closest and most remarkable examples of a planetary nebula. It lies in the constellation of Aquarius (The Water Bearer), about 700 light-years away from Earth. This strange object formed when a star like the Sun was in the final stages of its life. Unable to hold onto its outer layers, the star slowly shed shells of gas that became the nebula. It is evolving to become a white dwarf star and appears as the tiny blue dot seen at the centre of the image at bottom of the page.

ESO's VISTA telescope, at the Paranal Observatory in Chile, has captured a striking new image of the Helix Nebula. This picture, taken in infrared light, reveals strands of cold nebular gas that are invisible in images taken in visible light, as well as bringing to light a rich background of stars and galaxies.

The nebula itself is a complex object composed of dust, ionised material as well as molecular gas, arrayed in a beautiful and intricate flower-like pattern and glowing in the fierce glare of ultraviolet light from the central hot star.

`The main ring of the Helix is about two light-years across, roughly half the distance between the Sun and the nearest star. However, material from the nebula spreads out from the star to at least four light-years. This is particularly clear in this infrared view since red molecular gas can be seen across much of the image.

While hard to see visually, the glow from the thinly spread gas is easily captured by VISTA's special detectors, which are very sensitive to infrared light. The 4.1-metre telescope is also able to detect an impressive array of background stars and galaxies. The powerful vision of ESO's VISTA telescope also reveals fine structure in the nebula's rings. The infrared light picks out how the cooler, molecular gas is organised. The material clumps into filaments that radiate out from the center and the whole view resembles a celestial firework display. Even though they look tiny, these strands of molecular hydrogen, known as cometary knots, are about the size of our Solar System. The molecules in them are able to survive the high-energy radiation that emanates from the dying star precisely because they clump into these knots, which in turn are shielded by dust and molecular gas.

It is currently unclear how the cometary knots may have originated. The Image below was made using the ESO's Visible and Infrared Survey Telescope for Astronomy (VISTA) that captured this unusual view of the Helix Nebula. The colored picture was created from images taken through Y, J and K infrared filters. While bringing to light a rich background of stars and galaxies, the telescope's infrared vision also reveals strands of cold nebular gas that are mostly obscured in visible images of the Helix.

 

                        

 

Image credit: ESO/VISTA/J. Emerson. Acknowledgment: Cambridge Astronomical Survey Unit

Comments

[California Z]

Is anybody else not seeing "a tiny blue dot" at the center bottom of the image?

[Douglas]

Yes, its there. On my high resolution screen it is only about a pixel in size.

[Douglas]

Its on the bottom image, not the top one.

[mote]

Could they be KBO's/Oort objects losing volatiles due to the radiation & expansion of the hot gas from the nova?

[cris]

I've done the math (anyone can do it). Alpha Centauri (the closest star to the Sun) lies at about 4 light years, or 252.288 AU (google it). If the Helix Nebula is 4 l.y. in diameter it's perfectly conceivable that the knots seen in the image have the diametre of our solar system. If you make a mental image of the Solar System where the distance between the Earth and the Sun represents one meter, that means that Alpha Centauri lies at a whoping 252 kilometers !!!! The astronomical distances are truly mind-blowing !!!

[cris]

I've done the math (anyone can do it). Alpha Centauri (the closest star to the Sun) lies at about 4 light years, or 252.288 AU (google it). If the Helix Nebula is 4 l.y. in diameter it's perfectly conceivable that the knots seen in the image have the diametre of our solar system. If you make a mental image of the Solar System where the distance between the Earth and the Sun represents one meter, that means that Alpha Centauri lies at a whoping 252 kilometers !!!! The astronomical distances are truly mind-blowing !!!

[California Z]

Cris,

That's why it's better to use logarithms.

[Josh Tao]

Just wonder what the future holds for us.