A new study has found that “super-planets” outside our solar system that are rich in hydrogen or helium may be more habitable than our own.
The researchers say that rocky exoplanets with atmospheres dominated by hydrogen and helium have surfaces warm enough to host liquid water.
The presence of liquid water is “fit for life,” so these planets could provide habitable conditions and exotic habitats for perhaps up to 8 billion years.
Rocky exoplanets – planets outside our solar system – with primordial atmospheres dominated by hydrogen and helium have surfaces warm enough to host liquid water, researchers say.
The new study was led by researchers at the University of Zurich in Switzerland and was published today in the journal natural astronomy.
They say these planets are likely “not much like our home planet” and might host organisms under very high pressures.
“Life on the type of planet described in this work would survive under conditions substantially different from most life on Earth,” the authors say.
The surface pressures in our results range from 100-1000 bar, which is the pressure range for ocean floors and trenches.
“There is no theoretical limit to the pressure on life, and some of the most extreme examples in the Earth’s biosphere thrive at around 500 bar.”
Billions of years ago, the early universe contained only hydrogen and helium, and gases, which were readily available in the constituent materials of planets around young stars, such as our sun.
Therefore, all the planets formed atmospheres that were dominated by these two elements, including the Earth.
“When the planet first formed from cosmic gas and dust, it collected an atmosphere consisting mostly of hydrogen and helium – the so-called primordial atmosphere,” said study author Ravit Heald of the University of Zurich.
However, over the course of their evolution, rocky planets including Earth have lost this primordial atmosphere in favor of heavier elements, such as oxygen and nitrogen.
When our planet first formed from cosmic gas and dust, it gathered an atmosphere made up mostly of hydrogen and helium – the so-called primordial atmosphere
However, other, more massive planets can accumulate much larger primordial atmospheres, which can hold them indefinitely in some cases.
“Such massive primordial atmospheres can also cause a global warming effect – much like Earth’s atmosphere today,” Held said.
So we wanted to see if these atmospheres could help create the necessary conditions for liquid water.
For the study, the team modeled nearly 5,000 exoplanets, some bound to its star and some free-floating, and simulated their evolution over billions of years.
The researchers took into account not only the properties of the planets’ atmosphere, but also the intensity of the radiation of their stars as well as the internal heat of the planets radiating outward.
While this geothermal temperature is present on Earth, it plays only a secondary role to conditions at the surface, and can contribute even more to planets with massive primordial atmospheres.
An exoplanet is any planet outside our solar system. Most stars orbit other stars, but free-floating exoplanets, called rogue planets, orbit the center of the galaxy and are unrelated to any star (file photo)
The results suggest that depending on a planet’s mass and how far it is from its star, these planets can maintain a moderate surface environment for up to 8 billion years, provided the atmosphere is thick enough – 100 to 1,000 times thicker than Earth.
“What we found is that in many cases, the primordial atmosphere was lost to intense radiation from stars, especially on planets close to their star,” said Marit Mole Los, PhD student and lead author.
“But in cases where atmospheres remain, the right conditions for liquid water can occur.”
“In cases where sufficient geothermal heat reaches the surface, radiation from a star like the Sun is not necessary until conditions at the surface prevail that allow liquid water to exist.”
“Perhaps most importantly, our results show that these conditions can persist for very long periods – up to tens of billions of years.”
The researchers say instruments such as the James Webb Space Telescope, currently in space, and the Very Large Telescope, under development, should reveal more about vital signs in the atmospheres of exoplanets.
NASA confirms that there are more than 5,000 planets outside our solar system
NASA has confirmed that there are more than 5,000 known planets outside our solar system, known as exoplanets.
The US space agency has added 65 more exoplanets to the Internet NASA’s Exoplanet Archivebringing the grand total to 5,009 as of April 1, 2022.
That number was at 5,005 on March 22, which indicates that four planets were added to the total in just 10 days.
The database showed that as of June 8, there were 5,044 exoplanets.
The exoplanets found so far include small rocky worlds like Earth, gas giants several times larger than Jupiter, and “hot Jupiters” in very close orbits around their stars.
The more than 5,000 confirmed exoplanets in our galaxy to date include a variety of species – among them a mysterious group known as ‘super-Earths’ because it is larger than our world and possibly rocky
However, NASA asserts that only a “small portion” of all the planets have been found in the Milky Way alone.
The majority of the outer planets are gaseous, such as Jupiter or Neptune, not terrestrial, according to NASA’s online database.
Most exoplanets are found by measuring the opacity of a star that happens to have a planet passing in front of it, called the transit method.
Another method for detecting exoplanets, called the Doppler method, measures the “wobbles” of stars due to the gravitational force of orbiting planets.
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