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Hunting Planets II

August 27, 2015

MICHAEL ENDL: We are in the control room of the Harlan J. Smith 2.7-meter telescope at McDonald Observatory. And we are here because I have an observing run — four nights to use the telescope to search for extrasolar planets.

Michael Endl is continuing a search that’s been going on for a decade and a half. A score of McDonald Observatory astronomers and students have used the same telescope and spectrograph that Endl is using to keep a sharp eye on about 200 stars. They’re looking for planets in orbit around those stars — especially worlds that are similar to Jupiter in our own solar system: giant planets in distant orbits.

ENDL: The measurements that we are trying to perform are extremely exquisite. They’re very, very precise....We are measuring the velocities of stars. And we are looking for changes in the velocities of the stars due to an orbiting companion.

An orbiting planet exerts a gravitational pull on its parent star. As seen from Earth, that causes the star to “wiggle” back and forth a bit. But that wiggle is tiny — it might change the star’s apparent speed by just a few miles per hour.

Detecting such a change takes many observations, spaced over several years. In fact, the Texas astronomers have spent more than a thousand nights at the Harlan Smith Telescope, and have made up to a hundred or more observations of each target star.

We’ll talk about how their work is helping us understand how our solar system compares to others tomorrow.

Script by Damond Benningfield, Copyright 2015

Today's program was made possible in part by a grant from the National Science Foundation.

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