The Earth. A new study suggests that other stars could have up to 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 Journal,,
The search for life in outer space is usually focused on what scientists call the “habitable zone,” which is the area around a star in which an orbital planet could have liquid water oceans – a condition for life as we know it.
Kane studied a nearby solar system called Trappist-1, which has three Earth-like planets in its habitable zone.
“It made me think about the maximum number of habitable planets the star could have, and why our star only has one,” Kane said. “It didn’t look fair!”
His team created a model system in which they simulated planets of different sizes orbiting their orbits. An algorithm takes into account gravitational forces and helps test how planets interact with each other over millions of years.
They found that it is possible for some stars to support as many as seven and one star, such as our sun, potentially supporting six planets with liquid water.
“More than seven, and the planets are getting too close together and destabilizing their orbits,” Kane said.
Why then does our solar system have only one habitable planet if it is able to support six? It helps if the movement of the planets is circular, not oval or irregular, minimizing any close contact and maintaining stable orbits.
Kane also suspects Jupiter, which has a mass two and a half times that of all the other planets in the solar system, combines and limits 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.
It is known that only a handful of stars 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 major targets for direct imaging with NASA telescopes, such as the one in the Exoplanet Observatory of the Jet Propulsion Laboratory.
Kane’s study identified one such star, Beta CVn, which is relatively close at a distance of 27 light-years. Since there is no Jupiter-like planet, it will be included as one of the stars tested for many habitable zone planets.
Future research will also include the creation of new models that study the atmospheric chemistry of habitable zone planets in other stellar systems.
Projects like these offer more than new paths in the search for life in space. They also offer scientists a look at the forces that could one day change the lives of our own planet.
“Although we know that the Earth has been habitable for most of its history, many questions remain about how these favorable conditions have evolved over time and the specific drivers behind these changes,” Kane said. “By measuring the properties of exoplanets whose evolutionary pathways may be similar to ours, we get a visualization of the planet’s past and future – and what we need to do to maintain its habitability.”
Six billion Earth-like planets in our galaxy, according to new estimates
Stephen R. Kane et al., Dynamic Packaging in the Habitat Zone: The Beta CVn Case, The Astronomical Journal (2020). DOI: 10.3847 / 1538-3881 / ab9ffe
Provided by the University of California, Riverside
Quote: Surprising number of exoplanets could 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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