Planet Found Orbiting a Red Giant

About 5 billion years from now, our Sun will begin to run out of hydrogen, and swell up to become a red giant. The inner planets will be consumed, and the outer planets will have to deal with a much larger star. What will happen to the planets? We can’t know for sure, but a legendary team of planet hunters have discovered a planet orbiting another red giant.

A fateful look at things to come?

The discovery of a red giant star with a planet was made by Alex Wolszczan. If you don’t recognize the name, I’ll give you a little backgrounder. Wolszczan and his team were the first to discover planets orbiting another star – well, a pulsar actually, back in 1992. Subsequent observations have turned up entire solar systems of objects orbiting pulsars.

Alright, back to this discovery. Wolszczan and his team used the Hobby-Eberly Telescope – one of the largest and most powerful telecopes on Earth – to find a planet orbiting a red giant star. This star has approximately twice the mass of our own Sun, but it’s 10 times the size.

The planet orbits its star every 360 days, and was discovered using the Doppler shift technique. It was found because the pull of the planet’s gravity yanks its parent star back and forth. The change in this velocity is detectable by the Hobby-Eberly Telescope.

The discovery is important because it gives astronomers an idea of the fate that awaits our own Sun. Within 2 billion years, life on Earth will probably be unsustainable. And 5 billion years from now, our own Sun will become a red giant. As the star swells up, its changing density and gravity will disrupt the dynamics of the whole solar system. Planets will be pulled inward, and others will be flung out into space. Frozen moons orbiting giant planets like Jupiter might thaw out, and enter the star’s habitable zone for a brief period of time.

The more data astronomers can gather about this time, the better. And more data is coming. Wolszczan and his team have spent the last 3 years collecting data on over 300 stars, trying to identify ones which are good candidates for planets. So stay tuned.

Here are some previous stories on Wolszczan’s discoveries

• Smallest Extrasolar Planet Found
• Astronomers Weigh a Pulsar’s Planets
• Pulsars Form Planets Too

And some stories on red giants:

• Deathwatch on a Red Giant Star
• Red Giant Spotted Swallowing its Planets
• Outer Planets Could Warm Up as Sun Dies
• Stars Can Survive Being Engulfed

Original Source:Penn State News Release