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A surprising number of exoplanets can host life



A surprising number of exoplanets can host life

The Trappist-1

planetary system has three planets in its habitable zone, while our system has only one. Credit: NASA / JPL-Caltech

Of the Earth. A new study shows another star could have seven planets like Earth in the absence of a gas giant like Jupiter.

This is the conclusion of a study led by UC Riverside astrobiologist Stephen Kane published this week The Astronomical Journal.

The search for outer space life is typically focused on what scientists call a “habitable zone,” which is the area around a star in which an orbiting planet can have oceans of liquid water. – a condition for life as we know it.

Kane has been studying a nearby solar system called Trappist-1, which has three Earth-like planets in its habitable zone.

“This made me wonder about the maximum number of habitable planets that are possible for a star to have, and why our star has only one,” Kane said. “It didn’t look fair!”

His team created a system of models in which they simulated planets of various sizes orbiting their stars. An algorithm corresponded to gravitational forces and helped test how planets interacted with each other over millions of years.

They found that it is possible for some stars to support up to seven, and that a star like our sun could potentially support six planets with liquid water.

“More than seven, and the planets become too close to each other and destabilize each other’s orbits,” Kane said.

Why then does our solar system have one habitable planet only if it is able to sustain six? It helps if the motion of the planets is circular rather than oval or uneven, minimizes any close contact and maintains stable orbits.

Kane also suspects that Jupiter, which has a mass two and a half times that of all the other planets in the combined solar system, has limited the habitability of our system.

“It has a big effect on the habitability of our solar system because it’s massive and disrupts other orbits,” Kane said.

A small number of stars are known to have multiple planets in their habitable zones. Moving forward, Kane plans to search for additional stars completely surrounded by smaller planets. These stars will be the main targets for direct imaging with NASA telescopes such as that at the Jet Propulsion Laboratory’s Exoplanet Habitat Observatory.

A Kane study has identified one such star, the CVn Beta, which is relatively close to it at 27 light-years away. Because it does not have a planet like Jupiter, it is included as one of the controlled stars for multiple habitable zone planets.

Future studies also involve the creation of new models that examine the atmospheric chemistry of habitable zone planets in other star systems.

Such projects offer more than new avenues in the search for life in outer space. They also offer scientists an insight into the life-changing forces on our own planet one day.

“Although we know that the Earth has been habitable for much of its history, many questions remain regarding how these favorable conditions have evolved over time, and the specific drivers behind those changes,” Kane said. “By measuring the properties of exoplanets whose evolutionary paths may be similar to our own, we get a preview of the past and future of this planet – and what we need to do to generate habitability. her. ”


According to six billion Earth-like planets in our galaxy, according to new estimates


More information:
Stephen R. Kane et al, Habitat Dynamic Packaging: The Case of Beta CVn, The Astronomical Journal (2020). DOI: 10.3847 / 1538-3881 / ab9ffe

Provided by the University of California – Riverside



Citation: A surprising number of exoplanets can host life (2020, July 31) retrieved on July 31, 2020 from https://phys.org/news/2020-07-exoplanets-host-life.html

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