Ann Kellan on why astronomers 'follow the water'

Ann Kellan

Astronomers say a giant star in its death throes seems to be vaporizing a host of comets, raising the possibility that another planetary system possesses water, an ingredient necessary for known life. CNN Science Correspondent Ann Kellan explains.

Q: Tell us a little bit about the dying star? How far away is it? How big is it? When will it be declared dead?

KELLAN: Its name is CW Leonis, better known to astronomers as IRC+10216. It is about 200 parsecs, or 650 light years away. In the infrared spectrum, it is the brightest star in the sky -- after our own sun, of course!

CW Leonis is a red giant, which means it is dying. It is burning up its nuclear fuel supply and expanding, shedding material from its outer layers rapidly. Eventually, after about 10,000 to 30,000 years or so, scientists think it may become a planetary nebula.

Q: Does the dying star pose any danger to Earth?

KELLAN: It poses no danger to Earth.

Q: How are scientists getting their information about the star? Are they watching it with a telescope or are they using a satellite to study it?

KELLAN: NASA is using a satellite called SWAS, which stands for Submillimeter Wave Astronomy. It studies interstellar gas clouds and their chemical composition. According to the NASA Web site, "The primary objective of SWAS is to survey water, molecular oxygen, carbon and isotopic carbon monoxide emission in a variety of galactic star forming regions."

Q: Why is the star dying?

KELLAN: It has burned out its nuclear fuel supply. When that happens, the star begins to shed its outer layers and expands into a Red Giant.

Q: What do researchers hope to learn from the dying star?

KELLAN: By studying a dying star, scientists will better understand the evolution of planetary systems like our own solar system.

Q: What does a dying star have to do with the search for life on other worlds?

KELLAN: In this case, scientists are seeing signs of water surrounding this dying star. Water is a sign of life as we know it. So scientists want to know if planets like ones in our solar system once existed around this star and if life existed there.

Q: Will the research on the dying star help us better understand our own sun?

KELLAN: Sometime in the future, about 6 billion years from now, our sun will burn out its nuclear fuel supply and expand -- its atmosphere growing to about the orbit of the planet Earth, sizzling and evaporating everything in its path.

Our story today shows that this type of expansion and evaporation is possibly happening in a solar system similar to ours, around the star CW Leonis. In the search for life outside our own solar system, the mantra has been, "follow the water."

That's exactly what scientists think they've found around CW Leonis -- water vapor from what they think was a belt of comets surrounding the star that are now beginning to melt.