Date: February 6, 2011

Title: Finding Exoplanets, Part 3

Podcaster: Thomas Hofstätter

Organization: :: The Hidden Space Project :: at http://hidden-space.at.tf.

Description: This podcast discusses the topic of Exoplanets and life on other planets out of our solar system. If you have any questions, comments or suggestions to the podcast, feel free to write me an email to hidden-space (at) gmx (dot) at or visit me at my website at www.hidden-space.at.tf!

Bio: Born in 1993 near Vienna, Austria, Europe. Upper High School with focus on Computer Science.Interested in extreme small and extreme big, devious and uninvestigated things. My main aim is to bring astronomy to public and to establish secular interest in astronomy, physics and mathematics. Host of :: The Hidden Space Project :: at http://hidden-space.at.tf.

Today’s sponsor: This episode of “365 Days of Astronomy” is sponsored by Neil Christie. Those who can Podcast, those who can’t donate.

Transcript:

Hello and welcome to this episode of 365 Days of Astronomy. My name is Thomas Hofstätter and I am the hoster of :: The Hidden Space Project :: at www.hidden-space.at.tf.

[Leon:] And I’m Leon Dombroski from the state of Connecticut in the United States.

In this and other episodes we are going to talk about Exoplanets. We will have a look at the origin of thinking of life in other planetary systems as well as the science and technology behind the discovery of planets like in our own solar system.

[Leon:] Besides the methods for finding exoplanets which have been discussed earlier, there are also some technologies which require other high-tech instruments with extremely high quality in resolution and light level.

Scientists are especially lucky if the planetary system lies edge-on to our point of view. That means that the planets are moving in front or behind the star every orbit period. Due to the fact that the planet itself isn’t shining, a small part of the star’s luminosity is hidden every time the planet passes in front of the star. Scientists call this a “transit”.

[Leon:] When investigating the star over a longer period of time, scientists can detect changes in brightness. When looking at the so-called light curve over the time, they can find out the diameter as well as the orbit period. The mass can be calculated from these data. Moreover, they can get information on the composition of the planet (which mostly is a Hot Jupiter).

The Hubble Space Telescope – just like so often – was the first to reach this type of information. They investigated the star HD 209458 in the constellation Pegasus about 150 million light years away from earth.

[Leon:] This observation was possible because every time, the planet is passing in front of the star, little amounts of light are passing through the atmosphere of the planet, which makes it measurable for the Hubble Space Telescope.

When searching for life in the cosmos, the composition of the atmosphere is a significant criterion. Unfortunately, no planet has been found yet, that had the right conditions. Most of the known exoplanets are too hot to support life.

[Leon:] If the planet is massive enough, it’s also possible to detect is by using an effect caused by the general theory of relativity by Albert Einstein. According to this theory, space and time are not constant but form something called “spacetime” which can be stretched by massive objects.

If two stars are directly in one line from our point of view, the foreground star is bending the light of the background star outwards. If there is also a massive planet orbiting the foreground star, this effect is higher. Therefore, the so-called gravitational lens is larger and changes with time when the planet moves around its host star.

[Leon:] The Hubble Space Telescope again was the first to measure this effect. When they imaged the globular cluster M22 in the constellation Sagitarius 10600 light years away from us, they found the effect at an orphan planet. While most of the planets have their parent star around which they are orbiting, this planet has been ripped out of its system by gravitational influences of the other stars.

In general, gravitational microlensing is a common feature to observe especially small objects like planets. But the effect doesn’t only depend on the object itself but also on the foreground and the background star.

That’s it for today. I hope, you enjoyed it. If you have any questions, comments or suggestions, write me an email to hidden-space (at) gmx (dot) at or visit me at my website at www.hidden-space.at.tf.

Thanks for listening and clear-skies!
[Leon:] Good bye for now!

The next storries of this series will go on air soon!

End of podcast:

365 Days of Astronomy
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