Earth. A new study shows that other stars could have as many as seven Earth-like planets 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 in Astronomical Magazine.
The search for life in outer space has typically focused on what scientists call the “habitable zone,” which is the area around a star in which a surrounding planet may have oceans of liquid water – a condition for life as we know.
Kane had studied a nearby solar system called Trappist-1, which has three Earth-like planets in its habitable zone.
“It made me wonder about the maximum number of habitable planets it is possible for a star to have, and why our star has only one,” Kane said. “It didn’t look right!”
His team created a model system in which they simulated planets of different sizes orbiting their stars. An algorithm constituted gravitational forces and helped test how the planets interacted with each other over millions of years.
They discovered that it is possible for some stars to support as many as seven, and that a star like our sun could potentially support six planets of liquid water.
“More than seven, and the planets get very close to each other and destabilize each other’s orbits,” Kane said.
Why then does our solar system have only one habitable planet if it is capable of supporting six? Helps if the motion of the planets is circular rather than oval or irregular, minimizing any close contact and maintaining stable orbits.
Kane also suspects Jupiter, which has a mass twice and a half compared to all other planets in the combined solar system, limited the habitableness of our system.
“It has a huge effect on the flatness of our solar system because it is massive and disturbs other orbits,” Kane said.
Only a handful of stars are known to have many planets in their habitable zones. Moving forward, Kane plans to look for additional stars completely surrounded by smaller planets. These stars will be the main targets for direct images with NASA telescopes like the one at the Jet Propulsion Laboratory Habitat Exoplanet Observatory.
Kane’s study identified one such star, Beta CVn, which is relatively close to 27 light-years away. Because it does not have a Jupiter-like planet, it will be included as one of the stars controlled for multiple planets in habitable zones.
Future studies will also include the creation of new models that examine the atmospheric chemistry of habitable planet planets in other stellar systems.
Projects like these offer more than just new ways of searching for life in outer space. They also provide scientists with an insight into the forces that could change life on our planet one day.
“Although we know that the Earth has been habitable for most of its history, many questions remain about how these favorable conditions evolved over time, and the specific drivers behind these changes,” Kane said. “By measuring the properties of exoplanets, whose evolutionary paths may be similar to ours, we get an idea of the planet’s past and future – and what we need to do to support its habitat.”
About six billion Earth-like planets in our galaxy, according to new estimates
Stephen R. Kane et al, Dynamic Packaging in the Famous Area: The Case of Beta CVn, Astronomical Magazine (2020). DOI: 10.3847 / 1538-3881 / ab9ffe
Provided by University of California – Riverside
citation: Surprising number of exoplanets could host life (2020, July 31) Retrieved July 31, 2020 from https://phys.org/news/2020-07-exoplanets-host-life.html
This document is subject to copyright. Except for any fair action for the purposes of private study or research, no part may be reproduced without our written permission. Content is provided for informational purposes only.