At least one of the seven rocky planets orbiting the dwarf star TRAPPIST-1 may be an oceanic world similar to Earth, say scientists who have created updated climate models for exoplanets. Researchers at the University of Washington in the United States said that because of the extremely hot, bright early stellar phase, all seven star worlds may have evolved like Venus. In some of the early oceans, the planets may have evaporated, leaving behind a dense, uninhabitable atmosphere.
“We are modeling unfamiliar atmospheres, and not only assume that what we see in the solar system will look like that of another star,” said Andrew Linkowski, a doctoral student at Washington University. “We conducted this study to show what these different types of atmosphere might look like,” said Linkowski, lead author of the study published in the Astrophysical Journal.
TRAPIST-1, located 39 light years from us, has about nine percent of the mass of the Sun and about 12 percent of its radius. The relatively cold star “M dwarfs” – the most common type in the Universe – has a radius of only slightly larger than the planet Jupiter, although it is much larger in mass. All seven TRAPPIST-1 planets are Earth-sized and three of them – planets designated e, f and g, are believed to be in their habitable zone, this space around a star, where a rocky planet can have liquid water on its surface, thereby giving life a chance.
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TRAPPIST-1 d crosses the inner edge of the habitable zone, and further, TRAPPIST-1 h, rotates only past the outer edge of this zone. “This is a whole sequence of planets that can give us an idea of the evolution of the planets, in particular around a star, which is very different from ours, with a different light from it,” said Linkovsky.
Models of radiation and chemistry teams create spectral or long waves for each possible atmospheric gas, allowing observers to better predict where to look for such gases in the atmosphere of exoplanets. The researchers said that when traces of gases are actually detected by Webb’s telescope or others, someday, “astronomers will use the observed shocks and vibrations in the spectra to determine which gases are present — and compare this to work like ours to say something about the composition of the planet, the environment and, possibly, its evolutionary history. ” He said that people used to think about the location of the planet around stars like the sun.
“But the stars of dwarfs M are very different, so you really need to think about the chemical effects on the atmosphere and how this chemistry affects the climate,” Linkovsky said. TRAPPIST-1 b, the closest to the star, is a hot world, too hot for even sulfuric acid clouds, like Venus, to form.
Planets c and d receive a little more energy from their star than Venus and Earth from the sun, and may be similar to Venus, with a dense, uninhabitable atmosphere. TRAPPIST-1 e is the most likely of the seven for placing liquid water on a moderate surface and would be an excellent choice for further study with regard to vitality.
The outer planets f, g and h can be Venus-like or can be frozen, depending on how much water is formed on the planet during its evolution. Linkowski said that in fact, any or all of the planets TRAPIST-1 may look like Venus, and any water or oceans burn for a long time. He explained that when water evaporates from the surface of the planet, ultraviolet light from the star breaks the water molecules, releasing hydrogen, which is the lightest element and can leave the planet’s gravity.
This can leave a lot of oxygen, which can remain in the atmosphere and irreversibly remove water from the planet. Such a planet may have a thick oxygen atmosphere, but not one generated by life, and different from anything that is observed.