Artist rendering of a planet in orbit around a red dwarf (Image Credit: Greg Bacon, STScI, ESA, NASA)

Despite all of the technological leaps made in recent times, the main method by which we find exoplanets is still pretty remedial. We mostly rely on something called the transit method. With it, astronomers study the light from stars and look for telltale dips of light, which happen when a planet passes in front of its Sun relative to our vantage point. Of course, we aren’t limited to using the transit method at all times. There are a few others — like the stellar fingerprinting method, and Doppler spectroscopy — with more popping up every day.

Now, a team of researchers, led by Prabal Saxena (from George Mason University, Virginia), have published a paper in the ‘Monthly Notices of the Royal Astronomical Society’ journal that puts forth a new way of finding extrasolar planets. They suggest that we may soon be able to find rocky, Earth-like planets by studying the way in which the gravity of host stars stretches them out.

This method isn’t exactly new. Technically-speaking, astronomers will still need to scour the skies for dips of light that indicate a star has an orbiting planet, but it could free up some of the precious observational time astronomers require to confirm these dips are consistent, and that there’s a good likelihood planets exist.

For their research, the team rendered several models of planets in orbit around red dwarf stars. Despite being much smaller, cooler and less luminous than their larger counterparts, they are ideal not just because they are the most common type of star in the universe, but because planets in red dwarf systems feel tidal forces more powerfully.

Generally, they orbit their parent star from a distance so small (sometimes just a few million miles), Mercury’s close proximity to the Sun seems downright comfortable. In this kind of arrangement, planets face many difficulties, from high temperatures, to heightened solar activity.

An artist’s impression of a stretched rocky planet in orbit around a red dwarf Credit: Shivam Sikroria)

It’s also common for planets to become tidally locked to their parent star (in the  same manner the Moon is tidally locked to Earth), and for the very fabric of their being to be stretched out by immense tidal forces exerted by the gravitational field of stars. The larger the planet, and the more appreciable the atmosphere, the easier it is to see the impact these effects have on planets from Earth. Therefore, astronomers are at a disadvantage when it comes to finding rocky worlds.

However, according to the scientists, their models show that “in these circumstances the distortion of the planets should be detectable in transit events, where the planets moves in front of their stars and blocks out some of their light.” Presently, only a small number of satellites have the capacity to find them, but more sophisticated observatories — like the upcoming James Webb Space Telescope (JWST) and the European Extremely Large Telescope (E-ELT) — these signals might be obvious.

They could also tell us other important details about the planets the method yields. As Prabal comments, “Imagine taking a planet like the Earth or Mars, placing it near a cool red star and stretching it out. 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.”

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