Sunday, October 24, 2010

NGC 6210 Nebula

Hubble took a deep look at NGC 6210, which is 6,500 light years away, in the constellation of Hercules

At the heart of NGC 6210 is a star slightly less massive than our sun that is in the last fitful stage of its life cycle. The star's death spasms have kicked off multiple shells of material with different degrees of symmetry, giving the NGC 6210 nebula its odd, bulbous shape.

The new Hubble image shows the inner region of the planetary nebula in unprecedented detail, where the central star is surrounded by a thin, bluish bubble that reveals a delicate filamentary structure. The glowing bubble appears to be intertwined with an asymmetric, reddish gas formation where holes, filaments and pillars are clearly visible.

Planetary nebulas are shells of gas and dust expelled by stars near the end of their lives. They are typically seen around stars comparable or smaller in size than the sun. Planetary nebulas are not related to planets as their name suggests, but instead earned the moniker because they resembled giant planets when viewed through early telescopes.

A star's life ends when it runs out of fuel for its thermonuclear engine. The estimated lifetime for a sun-like star is about 10 billion years.

What's left behind is a tiny, but very hot, star remnant known as a white dwarf. The white dwarf inside NGC 6210, which is visible in the center of the Hubble image, will cool down and fade very slowly.

According to stellar evolution theory, our own sun will experience a similar fate in approximately 5 billion years.

How long does the 'cooling down and fade slowly away" last? Is it 10,000 years or 1/2 a billion years?

What happens to the existing solar system around such a star, are the planets obliterated? Do they continue to orbit a common baricenter?

Do the planets gain substantial mass because of all the ejected stellar material that forms the nebula? Would a Jupiter size world in such a nebula gain enough mass to become a star out of the ashes to the prior star?


Paulie said...

Okay, when a star dies as a planetary nebula, then a white dwarf, the planetary systme does not survive. The gas ejected from the star would be like a massive solar wind, and would blow away the atmospheres of any planets. In our solar system, the gas (Jupiter & Saturn) and ice (Uranus & Neptune) giants would lose most of their mass, eventually all the way down to the solid core. The less massive Sun would not be able to hold them gravitationally, and the outer planets would drift off into interstellar space. However, I have read (I don't remember the source offhand, one of the major astronomy magazines about a year ago) that there is evidence that a NEW planetary system can form from the gas and debris ejected by a dying star. Pretty weird, but exoplanets were evidently discovered around a dying star that should have lost it's original planetary system.

Once a star becomes a white dwarf, I think it can take several million years to radiate it's heat away, possibly longer. The photons of light (sunlight) that we see today were created in fusion in the Sun's core hundred's of thousands to millions of years ago. The photons are absorbed by free electrons in the core and bounce around in a "random walk" until they reach the less dense outer layers of the Sun's photosphere, where they finally fly free, and take only 8 miutes to reach Earth. Again, weird. But true.

Jerry M. Weikle said...

Thanks for the contribution Paulie. I have read the the suns surface tempatures is 5,500 degrees F. The tempature of a white dwarf probably around 2,500 degrees F, hot enought not to walk on the surface anyway. So your correct that it would take several million years or even a several hundred million years to cool down further because of the heat generated deep within the core.

With the solar wind, even in the Red-Giant phase, the larger planets would loose volumn and mass. The eventual collapse into the White dwarf would destablize the outer orbits and the residual Jupiter might actually have an elliptical orbit but closer in around the white-dwarf.