White Dwarfs May Hold The Key To Finding Alien Life

[Judi Lynn]

2/26/2013 @ 12:24AM |1,610 views
White Dwarfs May Hold The Key To Finding Alien Life

At the end of one part of a star’s life, if it’s not massive enough to become a neutron star or black hole – which is the vast majority of stars – it will shed mass and eventually become a very dense type of star known as a white dwarf. White dwarves are no longer capable of the nuclear fusion that sustains our Sun and most other stars. However, its residual thermal energy is enough to sustain heat for billions of years as it slowly dissipates. Even white dwarves that are close in age to that of the universe still retain their heat.

It’s around these slowly dying stars that astronomers now think may show the first signs of life. At least, given the limits of our current technology. That’s the conclusion of researchers at the Harvard-Smithsonian Center for Astrophysics.

“In the quest for extraterrestrial biological signatures, the first stars we study should be white dwarfs,” said theorist Avi Loeb in a CfA press release.

So far, no planets have been found in the “habitable zone” of a white dwarf star – an orbit where liquid water could exist on the surface of the planet. However, the researchers believe that a survey of 500 or so dwarf stars could discover such a planet.

More:
http://www.forbes.com/sites/alexknapp/2013/02/26/white-dwarfs-may-hold-the-key-to-finding-alien-life/

[Permanut]

1. Fascinating..

Incredible that we can learn so much from observing stuff happening out there, and how much we still don't know.

[Fumesucker]

2. A white dwarf has a lot narrower Goldilocks Zone than does a star similar to our sun

Easier to detect life bearing planets but probably less likely to have them I suspect.

Plus any planet in the Goldilocks Zone around a white dwarf is going to have an orbital period you could measure with a stopwatch and will probably be tidally locked to boot, the weather on such a planet should be quite remarkable.

[jeff47]

3. Plus, wouldn't the habitable planets have been incinerated in the red giant phase?

For example, the Earth is likely to be destroyed by the red giant phase. At best all life will be incinerated and the atmosphere will be destroyed.

[muriel_volestrangler]

4. Indeed, as the Daily Galaxy blog points out:

When a star like the Sun dies, it puffs off its outer layers, leaving behind a hot core called a white dwarf. A typical white dwarf is about the size of Earth. It slowly cools and fades over time, but it can retain heat long enough to warm a nearby world for billions of years. Since a white dwarf is much smaller and fainter than the Sun, a planet would have to be much closer in to be habitable with liquid water on its surface. A habitable planet would circle the white dwarf once every 10 hours at a distance of about a million miles.* Before a star becomes a white dwarf it swells into a red giant, engulfing and destroying any nearby planets. Therefore, a planet would have to arrive in the habitable zone after the star evolved into a white dwarf. A planet could form from leftover dust and gas (making it a second-generation world), or migrate inward from a larger distance.

http://www.dailygalaxy.com/my_weblog/2013/02/-white-dwarf-stars-offer-best-potential-to-identify-habitable-planets.html

Which may explain why people haven't been rushing to examine white dwarfs so far - they may have just thought the chances of planets being in a stable orbit in the habitable zone is small.