Stretched-Out Rocky Exoplanets are Detectable in Transit Events

Astronomers may soon discover rocky planets that have been stretched out by the gravity of the stars that they orbit. The new findings could reveal a bit more about these alien planets.

So far, more than 1,800 planets have been discovered in orbit around stars other than our own sun. These exoplanets are incredibly diverse, ranging from rocky bodies to gaseous worlds. Orbiting their stars at different distances, they can be less than a million miles away from their star to nearly 100 billion miles.

What's interesting is that significant stretching can occur due to the tidal forces resulting from each star's gravitational field. In other words, these exoplanets stretch while orbiting their stars. In order to learn a bit more about this stretching, the researchers modeled cases where planets were in orbit close to small red dwarf stars, much fainter than our sun. The planets' rotation was locked, so that the worlds kept the same face toward the stars that they orbited.

So what did they find? In these circumstances, the distortion of the planets should actually be detectable in transit events, which is when the planets move in front of their stars and block out some of the stars' light. What's interesting is that if astronomers can find these extreme exoplanets, they may learn more about Earth-like planets as a whole.

"Imagine taking a planet like the Earth or Mars, placing it near a cool red star and stretching it out," said Prabal Saxena, one of the researchers, in a news release. "Analyzing the new shape alone will tell us a lot about the otherwise impossible to see internal structure of the planet and how it changes over time."

The findings reveal a bit more about how to detect and learn about exoplanets. This, in turn, will help pave the way to future studies.

The findings are published in the journal Monthly Notices of the Royal Astronomical Society.

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