Water is essential for life on Earth, but where does water on planets come from? Earlier, it had been suggested that water was supplied by comets, but new results published in Nature Astronomy by an international team of astronomers, including researchers from the University of St. Andrews, reveals that some planets may have had water since their creation.
Simulations performed as part of the new study, led by Professor Sean Raymond at the University of Bordeaux, show that the seven rocky planets orbiting the nearby star TRAPPIST-1 would have been torn to pieces by the impact of that number comets required to supply the current amount of water.
For at least one of these planets, water must therefore have been present since its formation, which sets basic environmental conditions for the emergence and development of life.
In contrast, our home planet Earth was born much less watery and experienced a massive bombardment that eventually formed the Moon as a result of a large impact body of a size comparable to Mars.
The potential diversity of planetary environments that could have supported the emergence of life is very remarkable. Instead of focusing on planets that look largely identical to Earth, it is worth studying such environments and their potential co-evolution with life in detail.
Patrick Barth, a PhD student at the Center for Exoplanet Science at the University of St. Andrews, said: “We found that the planet TRAPPIST-1 g has about 100 times more water than the Earth, which was gassed out of its molten interior when the planet was still very young instead of coming from impactors at a later date . “
Could a thick sea of water have formed on TRAPPIST-1 g? Is this good or bad for the origin of life? Does such a sea still live to this day, or is the water buried deep inside the interior? Upcoming large space telescopes such as NASA’s JWST will take a closer look at the TRAPPIST-1 system, especially in order to measure the chemical composition of its atmosphere.
Royal Society University Research Fellow, Dr. Ludmila Carone, whose work follows the source of water on alien worlds and Earth, and who is willing to join the University of St. Andrews, also worked on the research.
She said, “The TRAPPIST-1 planets show us that other worlds can be truly unique and very alien compared to our own Earth.”
Patrick added: “If life appeared in the alien world TRAPPIST-1 g, it must have been exposed to conditions very different from those that life encountered on the early Earth. Where would evolution have taken it?”
Image 1 Caption: TRAPPIST-1’s planets compared to Jupiter’s moons and planets in the solar system. Image courtesy of NASA / JPL-Caltech.
Image 2 Caption: An illustration showing what the TRAPPIST-1 system might look like from a vantage point near the planet TRAPPIST-1 f (right). Image courtesy of NASA / JPL-Caltech.
The article ‘An upper limit for late growth and water supply in the TRAPPIST-1 exoplanet system